PB8i-9
10409
TRANSPOltTATION
SAFETY
WASHINGTON,
D.C.
20594
AIRCRAFT
ACCIDENT
REPORT
COLLISION
OF
AERONAVES
DE
MEXICO,
S.A.
MCDONNELL
DOUGLAS
DC-9-32,
XA-JED
AND
PIPER
PA-28-181,
N489lF
CERRITOS,
CALIFORNIA
AUGUST
3’1,
1986
NTSB/AAR-87/07
UNITED STATES GOVERNMENT
TECHNIC
5
a
Performing Organization Name and Address
ational
Transportation Safety Board
Bureau of
Accident
Investigation
.
Washington, D.C. 20594
12.bponsoring
Agency Name and Address
NATIONAL TRANSPORTATION SAFETY BOARD
Washington,
0. C. 20594
15.Supplementary
Notes
I
REPORT DOCUMENTATION PAGE
3.Recipient’s
Catalog No.
6.Performing
Organization
Code
8.Performing
Organization
Report No.
lO.W&$J~i
t No.
11
.Contract
or Grant No.
13.Type
of Report and
Period Covered
Aviation Accident Report
August
31,1986
14.Sponsoring
Agency Code
16.Abstract
0n
August
31,
1986, about 1152 Pacific daylight time,
.Aeronaves
de Mexico,
$.A.,
flight 498, a DC-9-32, Mexican Registration XA-JED, and a Piper PA-28-181, United
tates Registration
N4891F,
collided over Cerritos, California. Flight 498, a regularly
scheduled passenger flight, was on an Instrument Flight Rules flight plan from Tijuana,
Mexico,
Angeles International Airport, California, and was under radar control by
the
Los
terminal radar control facility. The Piper airplane was proceeding from
Torrance, California toward Big Bear, California, under Visual Flight’ Rules, and was not
in radio contact with any air traffic control facility when the accident occurred.
The National Transportation Safety Board determines that the probable cause
of the accident was the limitations of the air traffic control system to provide collision
protection,
through both air traffic control procedures and automated redundancy.
Patton
contributing to the accident were
(1)
the inadvertent and
unauthorixed
entry of
into the Los Angeles Terminal Control Area and
(2)
the limitations of the
“*see
concept to ensure traffic separation under the conditions of the conflict.
.
collision: terminal control
ar
instrument flight rules; term
trol
facility;
traffic alert and collision
m;
TCAS;
air traffic control; ARTS;
r terminal system; see and avoid
18.Distribution
Statement
This document is available
to the public through
the National Technical
Information Service
Springfield, Virginia
22161
CONTENTS
. .
BXRCUTIVRSUMMARY
. .
;
. .
;
.
i
;
;
;
. . . . . . . . . . .
1.
ACTUAL
WPORMATION
...........
1.1 History of the Flights.
.............
1.2 Injuries to Persons
...............
L3
Damage to Airplanes
..............
1.4 Other Damage.
................
1.5 Personnel Information
.............
1.6 Airplane Information
..............
1.7 Meteorological Information
...........
1.8 Navigational Aids
...............
1.9 Communications.
...............
1.10 Aerodrome Information
.............
1.11 Flight Recorders.
...............
1.12 Wreckage and Impact Information
........
lJ3
Medical and Pathological Information.
......
1.14 Fire
...
;
.................
1.15 Survival Aspects
................
1.16 Tests and Research.
..............
1.16.1
Visibility and Vision Studies
........
1.16.2
Target Acquisition Performance
......
lJ7
Other Information
........
;
......
1.17.1
Aeromexico Flight Operation Procedures and
Training
...................
1.17.2
The Los Angeles Terminal Radar Control.
..
1.17.3
Air Traffic Control Procedures
.......
1.17.4
Terminal Control Areas
..........
L17.5
Traffic Alert and Collision Avoidance Systems
1.16 New Investigative Techniques
..........
1.16.1
Retrack Program
.............
2.
a,1
2.2
2.3
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..........
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..........
..........
..........
..........
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.
.
.
.
.
.
.
.
.
.
.
.
.
..e
.
.
.
.
.
...*
.
.
.
.
.
............................
...........................
Entry into the
!i’e&inh
‘cdnt’roi
Aria
:
................................
ARTSIII.....O
.....................
C Procedures.
.........................
See and Avoid.
..........................
S.....................*
....
Cause
..e......*..........,
........
.........................
ENDATIONS
.......................
52
ndations Addressing Midair Collision
.............
52
V
1
ii
3”
3
4
5
5
6
i
10
12
ii
13
it
15
15
19
26
32
33;
36,
xi
z!
44
45
49
52
52
52
iii
ApPBNlrarss....1......1(tt;
;;;;;;;;r,
Appendix A-Investigation and Hearing
.....
1
.
i
.
c
!
i
1
.
i
.
Appendix B--Personnel @formation
Appendix C--FDR Data,
Aeromexico
..............................
1
1
Appendix D--CVR Transcript
....................
Appendix E--Cockpit Visibility Studies
................
Appendix P--ATC ‘lhnscript
....................
Appendix G--FAA Recommendations.
................
Appendix H--Mid-Air and Near Mid-Air Safety
Recommendations History
....................
._
.
55
55
8:
59
71
ii86
95
iv
EXECUTIVE SUMMARY
On August
31;
1986;
about 1152 Pacific daylight time; Aeronaves de Mexico,
§.A.,
flight 498, a DC-9-32, Mexican Registration XA-JED, and a Piper PA-28-181, United
States gistration
N4891F,
collided over Cerritos, California. Flight 498, a regularly
scheduled passenger flight, was on an Instrument Flight Rules flight plan from Tijuana,
Mexico, to Los Angeles International Airport, California, and was under radar control by
the Los Angeles terminal radar control facility.
‘Ihe
Piper airplane was proceeding from
Torrance, California toward Big Bear, California, under Visual Flight Rules, and was not
in radio contact with any air traffic control facility when the accident occurred.
The
collision occurred inside the Los Angeles Terminal Control Area near 6,560 feet
mean sea level. At the time of the collision, the sky was clear, and the reported visibility
was
14
miles. The air traffic controller providing service to flight 498 did not observe the
Piper airplane’s radar return on his display and therefore did not provide any traffic
isory to flight 498 concerning the location of the Piper airplane before the collision.
h
airplanes fell to the ground within the city limits of Cerritos. Five houses were
destroyed and seven other houses were damaged by airplane wreckage and postimpact
fire. Fifty-eight passengers and six crew members on the DC-9 were killed; the pilot and
2 passengers on the Piper were killed; 15 people on the ground were killed and 8 others
received minor injuries.
The National Transportation Safety
Board
determines that the probable cause of the
a&dent
was the limitations of the air traffic control system to provide collision
protection, through both air traffic control procedures and automated redundancy.
Factors
contributing to the accident were
(1)
the inadvertent and unauthorized entry of
PA-28 into the Los Angeles Terminal Control Area and
(2)
the limitations of the
“‘see
and avoid” concept to ensure traffic separation under the conditions of the conflict.
V
-2-
At
1147:28,
fliit 498 contacted the Los Angeles Approach Control’s Arrival
Radar-l
(AR-11
controller and reported that it was level” at 7,000 feet.
‘Ihe
AR-1
controller cleared flight 498 to depart Seal Reach on a heading of
320’
for the
ILS
(instrument landing system) runway “two five left final approach course...” Plight 498
acknowledged receipt of the clearance.
At
1150:05,
the AR-l controller requested flight
498 to reduce its airspeed to 210 knots indicated airspeed
(KIAS)
and the
flightcrew
acknowledged receipt of the request.
Between
1149:36
and
1149:52,
flight 498 contacted Aeromexico operations at
LA.
International on the company’s radio frequency with its arrival message and the
Aeromexico station agent gave the gate assignment to the flight.
At
1150:46,
the AR-l controller advised flight 498 that there was Traffic, ten
o’clock, one mile, northbound, altitude
unknown.rl
FIiiht
498 acknowledged the advisory,
but it never advised the controller that it had sighted the
“traffi&‘.
(This radar target was
not that of the Piper PA-28.) At
1151:04,
the AR-l controller asked the flight to reduce
its airspeed to 190
KIAS
and cleared it to descend to 6,000 feet.
Flight 498 acknowledged
receipt of the clearance.
At
1151:45,.
the AR-l controller asked flight 498 to maintain its
present airspeed.
‘Ihe
flightcrew asked the controller what speed he wanted and added that it
was *educing to . . . one niner zero.
”
At
1151:57,
the controller told the flight “to hold
what you have . . . and we have a change in
plans
for
you.”
At
1152:00,
plight 498 stated
that it would maintain 190
KIAS.
At
1152:18,
the AR-l controller advised flight 498 to
“expect the ILS runway two four right approach
. .
.”
niiht
‘498 did not acknowledge
receipt of this message, and the
1152~60
radio transmission was the Iast known
communication received from flight 498.
At
1151:18,
after flight 498 was cleared to descend to 6,000 feet, the pilot of
a Grumman Tiger
airpIane,
N1566R,
contacted the AR-l controller. At 115166, after
radio contact was established, the Grumman pilot informed the controller that he was on
a VFR flight from Fullerton to Monterey, California, via the Van Nuys,
CaIiforn!a,
VORTAC, that his requested en route altitude was 4,500 feet, and that he would like ATC
flight following services.
The
AR-l controller did not answer this transmission until
1152:04
when he requested the pilot to set his transponder to code 4524, a discrete
transponder code within the 4500 series used by approach control for VFR flights.
At
1152:29,
the controller asked the Grumman pilot if he was at
4,500
feet and the pilot
answered that he was climbing through 3,400 feet.
At
1152:36,
the AR-l controller told
the Grumman pilot that he was in the middle of the TCA and suggested that
“in
the future
you look at your TCA chart. You just had an aircraft pass right off. your left above you at
five thousand feet and we run a lot of jets through there right at thirty-five hundred.”
The AR-l controller testified that about
1152:36
he
also
noticed that the
ARTS III computer was no longer tracking flight 498. After several unsuccessful attempts
to contact flight 498, he notified the arrival coordinator that he had lost radio and radar
contact with the flight.
.
At about
11:52:
09, flight 498 and the Piper collided over Cerritos, California,
at an altitude of about 6,560 feet.
‘Ihe
sky was clear, the reported visibility was 14 miles,
and both airplanes fell within the city limits of Cerritos. Fifty-eight passengers and
6
crewmembers on flight 498 were
kilIed
as were the pilot and 2 passengers on the Piper.
The
wreckage and postimpact fires destroyed five houses and damaged seven others.
Fifteen persons on the ground were killed and others on the ground received minor
injuries. The coordinates of the main wreckage site were
33’
52’N
latitude and
118’
03’
“W
longitude.
-3-
Fatal
Serious
Minor
None
Total
7
60
23
90
I.3
Crew
7*
0
0
0
0
0
0
8
8
8
2
0
*Includes the pilot of the Piper PA-28
**Includes the passengers on the Piper PA-28
The DC-g-32 was destroyed by the collision, ground impact, and postimpact
fire.
‘Phe
Piper PA-28 was destroyed by the collision and ground impact. The estimated
vahes
of the
Piper
and the DC-9 were $28,000 and
$9,500,000,
respectively.
Pive
houses were destroyed and seven others were damaged by airplane
e and/or postimpact fires.
hformatian
fligbtcrew
and cabin crew of flight 498 were qualified in accordance with
exican,
United States, and company regulations and procedures.
‘Ihe
ion of the training records of the Aeromexico crew members did not reveal
extraordinary (appendix
B).
Further, the investigation of the background of the
rew
and their actions during the 2 to 3 days before the accident flight did not
thing remarkable.
e
air traffic controllers who
provided
ATC services to flight 498 were
ccordance
with current regulations.
The
examination of their training
id not reveal anything extraordinary (appendix
B).
In
addition, the investigation
oilers’
background and their activities during the 2 to 3 days before
uty on August 31 did not reveal anything extraordinary (appendix
B).
pilot of the Piper PA-28 was qualified in accordance with applicable
tions (appendix
B=)
the investigation, the Safety Board
who had flown with the of the PA-28, as well as his flight
, relatives, and colleagues
had flown with the Piper PA-28 pilot
m as a conscientious and careful
pilot*
One friend said that he was
“old
pt
with his preflight checklist, sometimes
Wo
careful” about rules, and aware of
Zs
low4imew
experience as a pilot.
pilot%
primary flight instructor stated that he had been a diligent
He said that he had taught the Piper pilot to scan for other
is scan pattern
“at
the left, scan, look at instruments, scan to the
truments,w
and then repeat the procedure.
He stated that the Piper pilot
h
the airplane% wing leveler equipment and that he used the wing leveler
ed”
to be used when looking at maps, reviewing charts, or doing other
in-
4
Another flight instructor who had provided instrument flight training to the
Piper pilot stated that they had discussed and used sectional charts during training and
that the training had included the numbers used on these charts to show the floor and
ceiling altitudes of a
TCA.
He said the Piper pilot was familiar with VFR
heqispherical
altitudes,
41
that he was a
“VFR
pilot who liked to look
out,”
and that he was more
inclined to navigate by visual reference to the ground than by use of navigational radio
aides.
The flight instructor also stated that he and the Piper pilot had discussed
TCAs
and
other types of restricted airspace, the equipment requirements for flying within restricted
airspaces, and the arrival and departure procedures used in the Los Angeles area.
‘Ihe
Piper pilot had moved to Los Angeles from Spokane, Washington, in
October 1985.
Gn
December 14, 1985, he received Los Angeles area familiarization
training and flew an area familiarization flight with a flight instructor. In March 1986, he
flew his airplane,
N4891F,
from Spokane to Los Angeles.
Since
December 1985, he had
flown seven flights in the Los Angeles area and had logged about 5.5 hours on these
flights.
1.6
Airplane Jnformation
The DC-932, XA-JED, was owned and operated by Aeromexico. Examination
of the
DC-S’s
flight and maintenance logbooks did not reveal any airplane discrepancies or
malfunctions that would have contributed to the accident. Examination of the
flight’s
dispatch documents showed that the airplane was operating within its allowable weight
and balance limitations. The DC-9 was treated aluminum with orange and blue trim.
‘Ihe
DC-9 had nose gear landing and taxi lights; one wing landing light in each
wing; anti-collision lights on top and bottom of the fuselage; ground floodlights in the left
and right side of the fuselage; and wing and nacelle flood lights on the left and right sides
of the fuselage. In accordance with company procedures, except for the nose gear landing
light, all lights are turned on when the airplane is below 10,000 feet.
The Piper PA-28-181,
N4891F,
a single engine fixed landing gear type airplane,
was owned by the pilot involved in the accident.
Rxamination of the airplane’s flight,
maintenance, and engine logbooks did not reveal any discrepancies that would have
contributed to the accident. Reconstruction of the airplane’s fuel, baggage, and passenger
seating locations on the accident flight showed that
N4891F
was operating within its
allowable weight and balance limitations.
N4891F
was equipped with a NARCO Model
AT-50A transponder without a mode C altitude encoder.
Given this transponder
configuration,
N4891F
could provide position but not altitude information to Los Angeles
Approach Control.
The evidence showed that the transponder was functioning properly
during the accident flight.
N4891F
was painted white with a double yellow stripe running longitudinally
along the fuselage.
The
registration number was blue and there were blue stripes on the
wheel pants.
N4891F
was equipped with navigation lights, a white anticollision strobe
light on each wingtip, a rotating red beacon atop the vertical stabilizer, and a landing
light on
its
nosegear. All the light switches were found in the
“on”
position in the airplane
wreckage.
w-s
4/
Pursuant to 14 CFR Part 91.109, each person operating an aircraft under VFR in level
flight more than
3.,000
feet above the surface and below 18,000 feet shall maintain the
following altitudes :
on a magnetic course of
zero0
through
179’,
any odd mean seal level
(MSL)
altitude plus 500 feet (such as 3,500, 5,500); on a magnetic course of
180°
through
3593
any even thousand feet MSL altitude plus 500 feet (such as 4,500, 6,500).
-50
N4891F
was equipped with an Autocontrol
BIB
autopilot, which is also called a
“wing
leveler.” The autopilot was a lateral control system, which provided only roll
control inputs to the airplane’s controls.
The airplane would hold a selected heading when
the autopilot’s heading switch was engaged.
The autopilot did not incorporate a radio
coupler and, therefore, the airplane could not fly with reference to a radio defined course.
The position of the autopilot’s control switches could not be determined during the
postaccident investigation.
Flight simulations were conducted during the investigation to determine
P3489kF’s
climb performance. A Piper PA-28-181,
N4305V,
configured similary to
N4891F
on the accident flight, was flown from Torrance Municipal Airport toward the location of
the collision using three different climb speeds: 76 KIAS, 80 KIAS, and 85 KIAS.
N4305v
reached the accident location and 6,500 feet in 11 minutes 31 seconds, 11 minutes 30
secondsp
and 11 minutes 45 seconds, respectively.
On the day of the simulation, the
temperatures aloft were almost identical to those recorded on the day of the accident;
the speed of the winds aloft were negligible from the surface to 7,000 feet, whereas on
the day of the accident the Piper may have had about a O-knot
tailwind
component
between about 5,300 feet and 6,500 feet.
1.7
The terminal forecast for LA International, issued by the National Weather
rvice
(NWS)
Los Angeles Forecast Office at 0818, August 31, 1986, and valid from 0900
st 31, to 0900 September 1, stated in part that after 1100 on August 31, the weather
would be clear.
Infrared photographs taken by the Geostationary Operational
Environmental Satellite (GOES) at 1031 and 1131 on August 31 did not show any clouds
over the land areas of southern California.
The 1146 surface weather observation at Fullerton Airport (about 4 miles east
of the accident site) stated in part that the weather was clear and the visibility
was
15
miles.
The 1149 surface weather observation at Long
Beach
Airport (about
6
miles
t of the accident site) stated in part that the sky was clear and the visibility was
The 1150 surface weather observation at L.A. International (about
18
miles
est of the accident site) stated in part that the sky was clear and the visibility was
14
miles.
San Diego, California, was the closest point to Los Angeles where NWS upper
data were available.
The 0400 San Diego sounding showed a strong
ersion
5/
with a base at 1,925 feet and a top at 3,102 feet; the atmosphere
above the
inqersion.
The 1600 sounding also showed the subsidence inversion.
was at 2,122 feet, the top at 3,070 feet, and the atmosphere was dry above the ,
reversions
At the time of the accident, the elevation of the sun was
61°
55’ above the
orizon with an azimuth (bearing from true north) of
148:
This is computed from
34’
0’
N latitude,
117Q56r
W longitude.
ere were no known navigational aids difficulties.
Ily
decreases with increasing altitude. An increase in temperature
e
is defined as a temperature inversion.
A subsidence inversion is a
inversion produced by the warming of a layer of subsiding (descending) air.
i’
-6-
There were no known communications difficulties.
LlO
Aerodrome
Jnformation
Torrance Municipal Airport, elevation 101 feet, is 3 miles southwest of
Torrance, California. The airport is served by two runways:
29L/llR,
and
29R/llL.
‘lhe
Piper PA-28 departed from runway
29R,
which is 5,000 feet long and 150 feet wide.
Los Angeles International Airport (LA. International), elevation 126 feet, is
served by two pairs of parallel runways; runways
25L/7R
and
25R/7L
are on the south side
of the airport’s terminal complex, and runways
24L/6R
and
24R/6L
are on the north side.
Runways
25L,
%R,
24L,
and
24R
are served by ILS approaches.
LA.
International is located near the center of its TCA. Except for a
triangular segment in the vicinity of Long Reach, California, the apex of which extends
northward from its southern boundary, the TCA is essentially a parallelogram.
Its western
and eastern boundaries are about 20 nmi and 25 nmi, respectively, from the western edge
of
LA
International. The
TCA’s
northern and southern boundaries are
essentiaIIy
paraIle1
to the extended centerlines of
L.
A. International’s four runways and are each about 10 nmi
from the center of the airport, respectively. (See figure 1.)
Vertically, the TCA resembles an “upside down” weddi
T
cake, beginning at
the surface at L.A. International and rising to a ceiling of 7,00 feet.
Proceeding
westward from the airport and aligned with the extended centerlines of the airport’s
runways, the floor of the TCA remains at the surface. Between 11 nmi and 20 nmi west
of the airport, the floor rises to 2,000 feet. A similar gradient exists along the eastward
extensions of the four runway centerlines.
To the north and south of the airport and the
extended centerlines of the four runways, the floor of
(See figure 1.)
the TCA rises sharply.
The lateral and vertical dimensions of the Los Angeles TCA are depicted on
the Los Angeles VFR Terminal Area Chart. On one side of the chart, the TCA is
superimposed on a
Lambert
Conformal Conic Projection map (figure
1);
the
chart’s
overleaf
contains a Charted VFR Flyway Planning Chart of the TCA (figure 2). In addition
to depicting the numerous airports in the
Los
Angeles area, the plan view also depicts
prominent landmarks within and adjacent to the TCA. For example, the planning chart
shows that Disneyland and the Anaheim Stadium are just east of the
TCAts
eastern
boundary. It also depicts and names the freeways located within and around the TCA.
Finally, the planning chart depicts the northsouth VFR flyway over
LA.
International and
the altitudes to be flown when using this flyway (figure 2).
The TCA charts show that Torrance Municipal Airport is under the southern
edge of the TCA and that the floor of the TCA above the airport
is
5,000 feet.
‘lbe
Piper
pilot bought a Los Angeles Sectional Chart and a Los Angeles VFR Terminal Area Chart
on the morning of the accident.
‘Ihe
Terminal Area Chart, folded to display the combined
map and TCA diagram, was found in the
been drawn on either side of the chart.
Piper’s cockpit wreckage; course lines had not
1.11
Fl&htRecorders
The Piper PA-28 was not equipped with nor was it required to be equipped with
flight recorders.
-7-
EVEN
+
p
-
--__--
I-‘-
\
-=-___
PACIFIC
OCEAN
Figure -2.
--Charted VFR Flyway Planning Chart of the TCA.
-9-
The DC-932 was equipped with a Sunstrand model F-542 Flight Data Recorder
(FDR);
serial No.5818, and a Sunstrand model V-557 Cockpit Voice Recorder
(CVR),
serial
No. 1829. Roth recorders were brought
.to,
the National Transportation Safety
Board’s
flight recorder laboratory in Washington D.C. for examination and readout.
The FDR had been damaged mechanically and by fire. Examination of the foil
magazine and the foil recording medium showed that the foil had been torn through, was
discolored from intense heat, and that all recorded traces were faint because of improper
stylus pressure. The faint traces and the heat discoloration made the recorded traces
difficult to read.
The
DC-S’s
latest FDR calibration data sheet was dated February
9,
1983, and
these data were used during the readout of the
FDR’s
foil. As a result of inconsistencies
in the recorded altitude data, adjustments were incorporated to obtain actual altitude
values.
The
field elevation at flight
498%
previous departure point, Tijuana, was 499 feet
and the
FDR’s
indicated altitude at Tijuana was -8 feet; therefore, a correction of 507
feet was added to the altitude data and the barometric pressures at Tijuana and Los
Angeles were assumed to have been 29.97 in Hg. No other corrections were made to any
of the other recorded parameters and a readout of the last 9 minutes of the flight was
made, a graphic display of which is appended to this report (appendix
C).
During the investigation,
the Safety
Board’s
Performance Group used the
recorded ATC radar data to reconstruct flight
498%
ground speed and indicated airspeed,
which they compared to the indicated airspeed recorded by the FDR.
‘Ihe
FDR-indicated
airspeeds were about 25 KIAS to 30 KIAS faster than the indicated airspeeds derived from
the recorded radar data.
Ihe
Safety Board believes that the indicated airspeeds derived
from the radar data are more accurate; therefore, 25 KIAS to 30 KIAS should be
subtracted from the FDR indicated airspeed.
The CVR was damaged slightly by impact forees and heavily by the
&-impact
fire.
The
CVR tape was not damaged physically and received only minor heat
e
The CVR recording started about
1122:17,
just after the engines were started at
The Safety Board CVR Group listened to the entire 30-minute recording and a
script was made of the last 11 minutes of the flight.
The verbatim
ns at
1141:21
when flight 498 was level at 10,000 feet and in radio contact
Control. The transcript continues to the end of the recording at
ew’s
primary language for all intracockpit conversation and for the
company was Spanish.
All ATC radio calls were in English.
ifi~~tiom
of the
crewmembers’
voices was made by members of the CVR Group, who
famili~
with the captain and first officer.
e quality of the entire recording w
consistently poor. The sound on the
crophone
(CAM) channel was extremely distorted, and it faded in and out
distortion and noise were so evident that the CVR Group found it very
stand the intracockpit conversation.
‘Ihis
difficulty was exacerbated by
use of the cockpit’s overhead speakers to receive ATC communications.
kers are very close to the CAM, the large number of radio transmissions
s
area, coupled with the loud volume of the radios, also impaired the
ibility
of cockpit conversation recorded by the CAM.
The poor quality of the CVR recording was not caused by either impact or fire
is model
CVR has a history of tape tension and recording quality problems.
of the tape causes permanent creases in the recording tape because it
places many times as it is pushed into the storage sleeve. In addition, if
is not set to provide the
d
uP
by the
capstan,
and
t
R
roper tension, the tape rides up on the record
e quality of the recording can be
degraded.
-lO-
Because of the poor quality of the CVR recording; it was necessary to include
ATC transmissions from the ATC transcripts to enhance the intelligibility of the CVR
transcript. The selected ATC transmissions were checked against the CVR recording to
verify that the selected transmissions were broadcast from the overhead speakers. Only
those verified ATC transmissions were included in the appended 11 minute CVR transcript
(appendix
D).
‘Ihe
CVR
transcript showed that the flightcrew received the LA
International Automated Terminal Information Service
(ATIS)
message at
1146:46.
Thereafter, the flightcrew began to prepare for landing and the intracockpit conversation
relating to these tasks ends at
1148:16
when the first officer said, “Flight director
up,”
in
response to the captain’s challenge.
Between
1148~16
and
1152:10,
six transactions were recorded by the CAM. At
1148:31,
an unintelligible word was recorded; at
1149:41,
a tone was recorded; at
115035,
an unintelligible female voice was recorded; at
1151:20,
an unintelligible word was
recorded; at
1151:30,
the captain said,
“Thank
you;”
and, at
1152:10,
the captain said,
“Oh,
thii
can%
be.”
The
1152:lO
remark was the last known remark made by either the captain
or first officer.
The CVR recording ended at
1152:32.
Between
1152:lO
and
1152:32,
three
ATC broadcasts were recorded, one of which was addressed to flight 498.
At
1152:18,
the
AR-l controller advised the flight that its landing runway was being changed to runway
24R; the flightcrew did not respond to this transmission.
With regard to air-to-ground
radio communications, the captain made all radio transmissions from
flight
498 to ATC
facilities.
Ll2
Wreckage ad Impact
mormation
The main wreckage sites of both airplanes were within the city limits of
Cerritos and within 1,700 feet of each other.
Piper PA-28-181,
N4891F--Except
for the upper portion of the fuselage
cockpit assembly, engine, vertical stabilizer, and instrument panel, the Piper remained
relatively intact after the collision.
The major portion of the Piper crashed in an open
schoolyard and did not catch fire after impact.
The engine of the Piper PA-28 separated from the fuselage and was found in
the yard of a residence about 1,650 feet north of the Piper’s main wreckage site.
‘lhe
engine had been damaged extensively by impact forces. Inboard of the No. 3 cylinder,
there was a 3 by
6-inch
hole in the top of the engine case.
A 5 by 8-inch piece from the.
upper vertical stabilizer of the DC-9 was lodged in this hole.
The propeller had separated from the engine.
One
propeller blade had broken
off about
18
inches from the
damaged heavily in the area o
B
repeller
hub. This blade was bent aft and was gouged and
separation and on its leading edge.
About 6 inches of the
tip of the opposite blade had broken off.
The remainder of this blade was bent aft and its
leading edge in the
midspan
area had been damaged by impact forces.
Roth wings were attached to the fuselage and their undersides were buckled.
The
top of the right wing was relatively undamaged. The top of the left wing had
numerous large deep gouges, scratches, and orange paint marks extending from the
outboard bulkhead to the wingtip. The gouges, scratches, and paint transfers were aligned
at a
30°
angle from the wing’s leading edge.
-ll-
The aft section of the fuselage
separated
just behind the
cockpit
assembly aft
bulkhead, but it remained attached to the forward portion by control cables and the
battery shelf attachments.
The
roof and upper portion of the cockpit assembly was
severed from the lower portion of the cockpit assembly along the bottoms of the cockpit
embly windshields and side windows.
‘Ihe
separation extended from the engine
firewall
aft to the cockpit assembly’s aft bulkhead.
The entire vertical stabilizer and rudder separated from the fuselage.
however,
except for a small aft section of the vertical stabilizer, these pieces were
recovered.
Most of the recovered pieces were buckled and torn severely. The lower
rtion
of the vertical stabilizer’s leading edge was dented, distorted, and torn by the
impact force.
The stabilator remained attached to the fuselage. The right stabilator was not
dam
d by impaat forces; however, the leading edge of the left stabilator was dented
about 18 inches inboard of its outboard tip rib.
The nose landing
ar separated from the airplane. The strut tube had broken
a rearward direction abou
inches
above the towing block.
The servo clutch of the Piper’s auto control system (wing leveler) was
ged; however, the clutch is designed to disengage when electrical power to the
is removed.
ion of the airplane’s altimeter showed that its
loo-foot,
l,OOO-foot,
ter assemblies were missing, and that its barometric gear train was
with
light finger pressure. Paint transfers similar to the paint used on
ters were found on the dial face (needle slapping) and the
%laptl
marks
o
the
6,560-foot
position on the altimeter dial.
airplane’s radios and transponders were recovered by outside personnel
qnd
to the wreckage collection site in the schoolyard adjacent to the Piper’s
e site, where they were examined by team members.
The following
were observed:
nder was set to code
1200,
The No.1
navIgationa
radio was tuned to 115.7 Mhz; this was the
published
radio frequency of the Seal Reach VORTAC. The OMNI
aring
Selector
(OBS)
was sot on 0913
The No.2 navigation radio was
d
to 112.2 Mhz; this was the
published radio frequency of the
radise
VORTAC. The OBS was
set on 0679
DC-9-32
-
The majority of the
DC- % wreckage fell within an area about a 600
00 feet wide. The wreckage in this area had disintegrated and was
The largest
piece
of wreckage was a section of the lower aft
ines
were found in this area and examination of their rotating
hat both were operating at high power at impact.
sion damage on the DC-9 was confined to the vertical and horizontal
eces
of the vertical stabilizer were scattered throughout the wreckage
om
the upper part of the vertical stabilizer were found near the Piper’s
ces from the lower part of the vertical stabilizer were in the
-12-
Pieces broken from the upper part of the vertical stabilizer’s leading edge
were positioned in their normal relative locations to each other.
IFxamination
of the
repositioned area disclosed a propeller slice, which began about 20 inches below the top of
the vertical stabilizer and was about 7 inches left of the airplane% centerline.
The
plane
of the slice was almost parallel to the longitudinal axis of the DC-9.
Recovered sections of skin from both sides of the vertical stabilizer were
examined. There was no evidence of impact damage on skin sections from the right side
of the stabilizer; however, some of skin areas from the left side had blue paint transfer
and tire marks.
‘Ihe
blue paint color was consistent with the paint on the nosewheel
fairing of the Piper.
‘lhe
smear marks extended aft and upward at a
28’
angle relative to
the rear spar of the vertical stabilizer and the marks were continuous with smear marks
on the left side of the rudder.
A gouge on the left side of the rudder extended upward at
an angle of
28’relative
to the rudder’s front spar.
‘l’he
end of the gouge crossed the top of
the rudder about
30
inches aft of its front spar and all of the rudder’s support hinges were
fractured.
‘Ihe
horizontal stabilizer separated during the collision and descended intact to
a location about 1,700 feet east of the
DC-Q%
main wreckage site.
l’he
leading edge of
the horizontal stabilizer left side was crushed, battered, and torn in several areas.
‘l’he
damage began about 1 foot outboard of the vertical stabilizer and extended to a point
about
13
feet outboard of the vertical stabilizer.
Human remains, debris from the
fuselage skin, and insulation from the upper right area of the Piper cabin just aft of the
main door frame were embedded in this area of the
DC-S’s
horizontal stabilizer.
In
addition to the damage described above, the left side of the horizontal stabilizer was
scratched and was smeared with white paint consistent in color with that of the Piper.
‘Ihe
scratches swept back from the leading edge at a
15’angle
relative to the front spar
of the horizontal stabilizer. Yellow and blue paint smears were also found at the outboard
end of the left horizontal stabilizer.
The horizontal stabilizer’s right side leading edge was crushed, but less than
the leading edge of the left side of the stabilizer.
Between 20 and 40 inches to the right
and outboard of the vertical stabilizer, the lower surface of this leading edge was crushed
and sliced consistent with damage resulting from a propeller strike.
The
line defined by
the slice swept back at an angle of
29O
relative to the front spar of the horizontal
stabilizer. Outboard of this damage, there were yellow paint smears and scratches on the
right horizontal stabilizer.
The yellow paint color was consistent with the Piper’s yellow
paint and the scratch marks
swept
back at a
35O
angle relative to the front spar of the
horizontal stabilizer.
1.13
Medical and Pathological Information
The captain and first officer of the DC-9 were killed by the ground impact
forces involved in the accident.
‘Iheir
bodies were fragmented too severely to permit
either an autopsy or toxicological test to be performed. The passengers and cabin crew
members on the airplane received multiple blunt force trauma injuries from the impact
forces and were burned in the postcrash fire.
The pilot and two passengers in the Piper were found in the remains of the
airplane’s cabin; they were strapped in the left front seat, the right front seat, and the
right rear seat. All three occupants had been decapitated.
-13-
i
An autopsy was performed by the Los Angeles County coroner on the pilot of
the Piper. With regard to the pilot’s general medical state, the medical examiner found
“generalized arteriosclerosis, slight to moderate and coronary arteriosclerosis, moderate
to focally severe with complete proximal occlusion of the main right coronary artery.”
The autopsy report issued by the Coroner of Los Angeles County ascribed the death of the
pilot of the Piper to
ttmultiple
injuries due to or as a consequence of blunt force.”
The
Armed Forces Institute of Pathology
(APIP)
also reviewed the autopsy
protcol
and the heart of the pilot of the Piper.
With regard to their examination of the
pilot’s heart, the AFIP pathologists found severe coronary
atheriosclerosis
but
‘ho
necrosis
or other evidence of acute myocardial infarction identified.”
Toxicological tests conducted during the postmortem examination of the Piper
pilot were negative for drugs and alcohol.
The carbon monoxide saturation level was well
below the levels required to produce incapacitation.
The AR-l controller agreed to and, on September 2, 1987, was tested for the
presence of drugs and alcohols; both tests were negative.
Fire
The DC-g-32 caught fire after it struck the ground. The postimpact fire
contributed to the destruction of the airplane.
‘Ihe
Piper PA-28 did not catch fire either
in flight or after it struck the ground.
The DC-932 was configured for a two-man flightcrew and 115 passengers.
Passenger scats were arranged into 23 rows of two seats located on the left side of the
cabin and 23 rows of three seats located on the right side of the cabin. A double
aft-
facing flight attendant seat was in the forward cabin near the main cabin door; another
double forward-facing flight attendant seat was located on the cabin’s aft bulkhead. The
entire cockpit and passenger cabin area of the DC-9 was destroyed by impact forces and
subsequent fire.
Only
one passenger seat was found intact; it had been thrown clear of
the fire and had penetrated a garage door.
e
cockpit-cabin area of the Piper
PA-28-181 was configured with
by-side pilot seats and side-by-side passenger seats aft of the pilot seats.
The
roof
abin
area was torn from the airplane and found away from the remainder
The accident occurred a considerable distance from any major airport and thus
despise
to the scene was the responsibility of municipal fire departments and law
enforcement agencies. Examination of the response times of these agencies showed that
arrived at the accident scene promptly. For example, one Los Angeles County Fire
rtment engine company received the alarm at 1153; at 1154, the engines were
tehed; and at 1158, the engines arrived on the scene.
-1%
display. The subject pilots acquired the intruder visually in 57 of the 66 encounters
(86
percent
of the total).
In
five of the nine failures, the failure was partially due to the
pilot’s response to a TCAS resolution advisory.
The median range of the visual
acquisitions was 1.4 nmi.
The performance of the pilots was used to provide data for a mathematical
model of visual acquisition. This model is based on the experimental observation that the
probability of visual acquisition in any instant of time is proportional to the product of the
angular size of the visual target and its contrast with its background.
‘ihe
cumulative
probability of visual acquisition is obtained by integrating the probabilities for each
instant as the target approaches.
.
The data cited herein were developed by a project leader on the Air Traffic
Control Division, Liieoln Laboratories, MIT, who had conducted research on human visual
performance and flight testing of collision avoidance systems. At the Safety
Board’s
request, the project leader constructed Probability of Visual Acquisition Graphs based on
the extrapolation of pertinent data contained in the facts and circumstances of the
collision between the Piper PA-28 and flight 498 with the data described above. (See
figures 3 and
4.)
The graphs are based on the closure rate between flight 498 and the
Piper and on the results achieved by pilots having an unobstructed view of the intruder.
The graphs do not account for such limiting factors as cockpit structure and the
ssibility that the airplanes might be positioned so that they can be seen with only one
eye
e
However, the information in this report is of significance in that it provides a
baseline for further evaluation.
Aeromexico Air Lines, a foreign air carrier, operates within the United States
ect to the provisions of 14 CFR Part 129. Pursuant to the provisions of 14 CPR Part
11,
Aeromexico must operate within the United States in accordance with Operations
cs)
issued by the Federal Aviation Administration (FAA). These
airports to be used, route or airways to be flown, and such
and practices as are necessary to prevent collisions between foreign
ther aircraft.” Pursuant to 14 CFR Part 129, Aeromexico fliihtcrews must
he provisions of the General Operating and Flight Rules contained in
14
CFR
g within the United States.
The
United States accepts the airman certificates issued by a foreign
ernme~t
as evidence that they have been
tearer
properly and are competent to
rm
their assigned duties within U.S. boundaries.
According to the manager of the
Los Angeles Flight Standards District Office
(PSDO),
the FAA has no reason to
ve that it is not justified in continuing this policy. The FSDO manager also testified
that the FAA does not
%onduct
en route inspections aboard foreign carriers outside the
United States. We do not routinely conduct en route inspections within the United States
unless
.
e
e
the foreign carrier requests it for safety reasons.”
The Aeromexico Flight Operations Manual contained a specific section
caRision
avoidance.
The section contains nine articles which, in addition to
their
flightcrews
to maintain vigilance, amplify and, in essence, reiterate the
rules contained in 14 CFR Part 91.67.
.
-16-
10
.
09
l
08
.
07
.
06
.
05
.
04
.
03
.
02
.
01
I
Time
to
Collision
(seconds)
5
10
15
20 25 30 35
40 45
50
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Range
(nmi)
Figure
3.0-Probability
of seeing the other aircraft
as a function of time until collision.
-17-
Time
to
Collision
(s
5
10
15
20
25
30
35
40
45
50
1.0
1.5
.5
3.0
3.5
4.0
Ran
Figure
4.--The
effect of
TCAS-type
alert on the
ability that the DC-9 pilot would see the Piper Aircraft.
-18-
‘Ihe
Aeromexico recurrent training requirements and
curricula
were almost
Jdentical
with those contained in the applicable sections of 14
CPR
Part 121, which apply
to United States air carriers.
Aeromexioo
DC-9 flightcrew members received recurrent
training twice a year.
Each
recurrent training session included 2 days of ground
school
during which aircraft systems were reviewed, and either 2 days of simulator or 1 day of
flight training on alternate training sessions.
Each
recurrent training session was followed
by an en route flight check, preferably to a destination in the United States.
‘Ihe
Aeromexico Plight Operations Manual stated that the cockpit door will be
closed but not looked during flight, and it limited the use of the observer’s seat (jump
seat) in
the:coekpit
to check pilots and to deadhead company pilots, company technical
personnel with proper written authorization, and ins
ctors
from the office of the
Director General of Civil Aviation of Mexico (DGAC .
The
Manual did not contain
r
specific
requirements to limit conversation within the cockpit or to prohibit the entry of
fli&
attendants during the takeoff, climb, descent, approach, and landing phases of
.
Company policy recommended the use of the autopilot for the descent into
LA.
International. According to an Aeromexico DC-9 captain and checkpilot, except for
““..
takeoff and landing, the autopilot was used throughout all flights. He testified that it was
normally turned on about 2,000 feet above the ground
(AGL)
on departure and remained on
until about
300
feet AGL, when it had to be turned off. He testified that he expected
that the autopilot would have been engaged when the collision occurred.
‘Ihe
checkpilot testified that he had flown from Tijuana to Los Angeles many
times.
He testified that company procedures required that all required paperwork be
completed while at cruise altitude; however, given the very short length of this flight, no
paperwork is done because of the cockpit workload.
According to the checkpilot, Aeromexico had a special abbreviated checklist
for use on very short flights or those flown below flight level
(FL)
240
x/.
He testified
that the flightcrew would call for and accomplish the approach checklist about
3
minutes
before starting the descent for landing.
He
testifed
that although the prelanding call to
the company was generally made 10 to 15 minutes before landing, given the length of this
flight and its workload, the call was made after the checklist was completed, but that,
“You
never start your descent if
yoube
not complying with the descent and approach
checklists.” He further testified that all checklists should have been completed by the
time flight 498 had descended through 7,000 feet.
The check captain was asked about the unintelligible female voice heard on
the CVR at
1150:05.
He testified that it could have been the flight attendant informing
the captain that the cabin was prepared for landing as
r
uired by company procedures; it
could also have been part of a Public Address
Syste:m
(PA announcement audible through
7
the
cabin
door. He said that noises occurring close to the cockpit door are heard in the
cockpit, and
“You
get all the PA announcements through the door.
You get all the
chimes.”
7/
A
levelxoonstant
atmospheric pressure related to a reference datum of 29.92 inches
o’t
mercury.
Each
is stated in three digits that represent hundreds of feet. For example,
FL
240
represents a
barametric
altimeter indication of 24,000 feet.
k
G
-2o-
If
the aircraft was a tracked target
-
an aircraft whose identity has been
inserted into, and therefore was tracked by, the ARTS III computer -- an alphanumeric
symbol would appear instead of a triangle or square.
Different symbols were used to
denote which control position had track control of the targets; targets tracked by the
AR-1 position were denoted by the letter
“D”.
All tracked targets have associated with
them a data block containing the aircraft identification, ground speed, altitude, and other
selected information. Flight 498 would have been displayed as a primary target, with a
beacon control slash, a
nDff,
and its data block.
The
lo-Channel
Decoder
-
‘lhe
TRACON also was equipped with an ATCBI-3
beacon system known as a
1O~hannel
decoder. The ARTS III with its internal
ATCBI-4
was designed to replace the lo-channel decoder.
Other ARTS III-equipped TRACONS use
their ARTS III as their primary traffic control system with the lo-channel decoder as a
back-up beacon-interrogator system; however, the Los Angeles TRACON used its
19-
channel decoder as the primary beacon-interrogator system.
’
Normally, channels 1 through 8 on the lo-channel decoder are preset and
contain 45 discrete beacon codes.
Channel 9 was not preset but was normally set on code
1200.
Channels 1 through 9 targets were displayed as two beacon control slashes on the
controllers’ display. Channel 10 was not preset but was normally set on code 4500 series
usually assigned to VFR traffic receiving advisory services within the
TRACON’s
airspace;
this traffic was portrayed as a triple beacon control slash on the controllers’ displays.
The
lo-channel decoder has an on/off switch that was normally left in the
nonn
,’
position at the Los Angeles TRACON.
When the beacon/analog switch on the controller’s
DEDS was
placed
in the
“beacon”
position, the
lO-ehannel
decoder supplied beacon data to
the DEDS. In this configuration, the previously described ARTS III alphanumeric
portrayals remained the same; however, except for the 4500 code, which was displayed as
a triple slash, beacon slashes were double.
In Los Angeles, two other changes were made to this configuration.
Channel 9, which contained the 1200 code, was turned off and the controllers, using the
ARTS III preselect function, displayed this code in the systems data area on their DEDS
displays. In this configuration, without mode C altitude data, a 1200 code appeared on the
displays only as a primary target and an alphanumeric triangle; there was no
accompanying beacon slash. A 1200 code with mode C data would have been displayed in
a like manner but with an alphanumeric square. The Air Traffic Manager of the Los
Angeles TRACON testified that, although there was no written policy, all controllers
were required to operate their DEDS displays in the above configuration. He testified
that channel 9 was turned off to avoid proliferation of beacon slashes on the controller’s
displays because of the large number of VFR aircraft in the
TRACON’s
airspace.
ARTS III Capacity
-
The
TRACON’s
ARTS III can store 180 tracked targets in
its central track store, and has a corresponding display buffer capacity for intermediate
storage of this information before it is sent to the controller% displays for presentation.
It can store 300 untracked targets in its untracked target buffer
8/
for presentation on the
DEDS.
If the tracked or untracked target data exceed the
capazities
of their respective
.
buffers, the incoming data cannot be placed in the buffers and therefore will not be
displayed on any of their displays.
‘lhe
presence of either one or both of these display
k/
Buffer--A temporary storage area of radar beacon targets that are eligible for display.
A tracked target is an aircraft whose identity- has been inserted into the ARTS III
computer and, therefore, is being tracked by the computer. An untracked target is a
target that has been recognized by and is, or can be, displayed by the computer.
-21-
buffer overload conditions will produce a printout on the Automatic Send-Receive
(ASR)-37
Console Typewriter at the ARTS III computer’s main terminal. Three separate
display out (DISOUT) messages can be generated to denote which buffer is overloaded or
to indicate that both are overloaded and that data is not reaching the DEDS. However,
the printout only appears on the ASR-37 at the computer’s main terminal; it is not
reproduced at the TRACON displays.
No DISOUT printouts were generated at the
TRACON on the day of the accident.
There is no priority between the tracked and untracked buffers. Data cannot
be removed from the untracked target buffer to accommodate tracked target data that
cannot be inserted into an overloaded tracked target buffer. Further, untracked targets
being displayed on the displays will not be removed to accept a tracked target from an
overloaded tracked target buffer.
The ARTS III computer also generates another type of message to indicate
that it is being overloaded. Whenever the number of active tracks data in either buffer
reaches 85 percent of its active track capacity, a printout is produced indicating this
condition. This condition was not indicated on any printouts on the day of the accident.
In addition, the displays can be saturated with alphanumeric data and they will
begin to
“flick&
as this condition approaches.
In order to maintain the alphanumeric
data on the controller% displays at a constant level of illumination, the data must be
refreshed 30 times per second. Flicker occurs when the computer
connot
refresh all the
alphanumeric data on the displays within the
alloted
time. Although data is not lost when
this occurs, the alphanumeric data presently displayed will begin to fade and reappear.
On the day of the accident, none of the TRACON controllers reported that such a
Vlickerl~
had
occurred
.
Finally, heavy Input/Output (I/O) Processor loading may be manifested by
another condition. If the amount of beacon data requested and the keyboard processing
increase to the point that the computer starts to fall behind, although no data
wlV
be lost,
the computer’s response to the keyboard entries would become sluggish. None of the
controllers on duty at the time of the accident either stated or testified that this
condition had occurred.
Maintenance History
-
The ASR-4 and
ASR-‘7
radars were commissioned in
1964 and 1973, respectively. The ARTS III was commissioned in 1973. In 1978, the radar
on both
ASRs
were upgraded and replaced with ASR-8 radar antennas.
to a radar technician in the FAA Airways Facility section at Los Angeles, the
ASR-4 has required more maintenance than the
ASR-7;
however, he testified that the
ASR-4 is a vacuum tube system and the tubes
‘Igo
bad.” Except for the magnetron, or
transmitter
tube, the ASR-7 is a solid-state radar.
Examination
of the maintenance records of the TRACON from
1, 1986, until the day of the accident did
ot
disclose any instances wherein the
N was unable to provide its required ATC services. However, between January
ust 1986, it had encountered problems that involved the receipt and processing of
ude information received from the mode C transponders. The computer had been
altitude information from the data blocks and, in addition, there was some code
on assigned radar codes. According to an FAA radar technician in depth
(RTID),
requested from the FAA regional office and headquarters in Washington, D.C.
The
major
source of the problem was traced to local interference and to several elements
of the beacon antenna
colocated
with the ASR-4 antenna that were functioning
roperly.
The beacon antenna was replaced and, according to the RTID, the problems
were resolved by the end of July and the system had been returned to
%ormal
service.”
-22-
During the week before the
acoident;
there were recurring problems with
channel A on the,
ASR-4.
J&ring
that period, channel A was out of service a total of 36
hours 44 minutes. However, radar services were supplied from channel B and if channel B
had failed, the TRACON could have switched to the
ASR-7
and continued to operate.
On
August 2, 1986, the ASR-4 channel B failed while. channel A was in the maintenance mode
for checking.
The
TRACON shifted to an all
ASR-7
operation for about 33 minutes until
channel A of the ASR-4 was available. The TRACON then shifted from the all
ASR-7
operation to “normal configuration with ASR -4 Channel A on
line.”
“Ihe
present radars at the TRACON are scheduled to be replaced by ASR-9
radars which, except for the magnetron tubes, are solid&ate radars.
‘Ihe
ASR-7
will be
replaced in mid-1987; the ASR-4 about a year later.
‘Ihe
later date for the replacement
of the ASR-4 was to accommodate local municipal authorities in resolving a re-siting
problem for the replacement radar.
Flight Inspections
-
On
A:;gust
31, after the accident, the Seal Beach VORTAC
and the
TRACONb
radar were fliiht checked by an FAA flight inspection airplane and
were found to be “operating satisfactorily.”
Two additional flight inspections were conducted, one on September 3, 1986,
and another on March 11, 1987. These two flight inspections of the
TRACON’s
radars
specifically explored the performance of the
TRACON’s
radars in the area and at the
altitude of the collision.
A radar beam in the earth’s atmosphere is subject to refraction-bending-due
to the variation of atmospheric density, which is a function of pressure, temperature, and
humidity.
‘Ihe
refraction power of the atmosphere increases with increasing pressure and
humidity and with decreasing temperature.
.
The
density of the atmosphere normally decreases with height and a radar
beam passing through this type of atmosphere is refracted to a curvature of
4/3
the
earth’s radius.
When the vertical refractive index is greater than that which produces the
4/3
curvature, the radar beam is bent somewhat more and the layer of the atmosphere is
described as
“superrefract
ive
“.
Atmospheric layers that produce greater refraction are
described as “trapping” layers.
If the radar beam enters a “trapping” layer at a shallow
angle, part of the beam becomes trapped because the refraction equals the curvature of
the “trapping” layer, which follows the curvature of the earth% surface.
This condition
can increase the range of the radar at the layer’s altitude; however, in extreme cases, the
index of refraction is so large that the radar beam
,returns
to earth, limiting the range of
the radar and increasing greatly the interference due to ground return.
A layer of atmosphere that refracts the radar beam less than normal ‘is
described
Wbrefractive”.
When a radar beam is refracted in this manner, the radar range
at a lower elevation is reduced because the beam
doe&t
curve as much toward the
earth’s
surface.
Under certain conditions, when a layer of atmosphere just above the radar
antenna has a large gradient of refractive index, part of the radar entering the layer at a
shallow angle is trapped while that entering at a steeper angle is not. The beam is split,
leaving a section of elevation angles with no radar energy; this is called a
“radar
hole”.
-23-
The Safety Board obtained low level radiosonde squndings
z/
from the
,South
Coast Air Quality Management
District
at El Monte,. California, for 1200, August 31, 1986
(the day of the accident), for 1200, September 3, 1986 (the day of the second flight
check), for 0600 Pacific standard time (the day a third flight check). These data were
used to plot refractive indexes.
The August 31 soundings showed
“‘superrefractive”
layers between 1,643 and
1,981
feet, between
4,336
feet
4,661
feet,
and
between
6,071
feet
and 6,754
feet.
There
was a
“trapping”
layer between 2,375 feet and 2,955 feet.
The September 3 sounding showed an inversion between 2,056 feet and 4,415
feet. There were “trapping” layers between 2,056 and 2,516 feet and between 4,100 feet
and 4,415 feet, and a subrefractive layer between 4,415 feet and 4,995 feet. Given the
@resence
of the two “trapping” layers above the radar antenna, there was probably more
refraction than on August 31.
On
September 3, 1986, a flight inspection of the
TRACON’s
ASR-4 radar was
oo~du~ted
with a Piper PA-28
N6701H.
During this inspection, five counterclockwise
orbits were flown around the Seal Reach VORTAC at 5,000, 5,500, 6,000, 6,500, and 7,500
feeto
The orbits were flown at a 5 nmi radius from the station. Thereafter, the route of
ecident
Piper PA-28 was duplicated.
The route was first flown in reverse from the
ion position to the Torrance Airport by departing the collision position at 6,400 feet
at 90 KIAS and descending at 700 feet per minute
(fpm).
A reciprocal route was then
flown by departing the location where radar tracking began at 90 KIAS and climbing at
700 fpm. The second track, which duplicated the course flown by the Piper on the day of
accident, was flown at the same time of day as the accident and was timed so that the
ht check airplane would arrive at the impact site at 1152.
During the flight, the ASR-4 radar and the ARTS III were configured as they
were at the time of the accident, and the strengths of the primary and secondary targets
were scored in accordance with the target strength parameters contained in paragraph
215,5
of the
PAA
Wight
Inspection
Handbook.
1v
The parameters contained in paragraph
215.5 for
sear
the strength of primary targets are in part as follows:
3
=
Usable
Target leaves a trail or persists from
scan-toscan
without trail.
2
=
Usable
v
shows each scan and remains on the scope for at least
l/2
of the scan.
1
”
Unusable
Tkssn
a strength 2
-target;
a weak target, barely visible;
possible miss.
0
=
Unusable
No visible target.
regard to secondary targets, paragraph 215.5 states:
1
=
Usable
‘I?@@
is satisfactory for ATC purposes.
0
=
Unusable
Target is unsatisfactory for ATC purposes.
~~~~ernemts
of wind, temperature, moisture, and height at
selected pressure
-24-
Paragraph 215.5 defines usable target strength as a
“target
which is not
missed/unusable on 3 or more consecutive
scans.”
The
collision site is located on the
35O’radial
of the Seal
Beach
VORTAC at 5
nmi from the station. Examination of the scores on the orbits between 5,000 and 6,500
feet and between the
270’and
015’radials
revealed the following:
9
tween the
355O
and the
016Oradials,
seven out of eight primary target
returns are unusable, the rest are u-sable.
All secondary targets are
usable.
5,500 feet
All primary and secondary targets are usable.
=%F
ee primary targets are unusable at the
328’,
342’
and
355’
radials.
‘Ihe
secondary targets are usable.
6,500 feet
There is one unusable ‘primary target
targets are usable.
at the
353’
radial.
All secondary
With regard to the two duplications of the accident airplane’s flightpath, all
secondary targets were usable.
On the descending flight toward Torrance, two primary
targets were unusable on the first and third sweep or scan of the antenna; the remainder
of the primary targets were usable.
On the climbing flight from Torrance to the impact
site, there were widely separated unusable primary targets, which were only one sweep in
duration. However, the primary targets were unusable during the last six sweeps of the
antenna before the airplane reached the impact site.
‘Ihe
flightcheck form also contains the outside air temperature recorded
during the flight check.
At 3,000, 4,000, 5,060, 6,000, and 7,000 feet, the following
centigrade temperatures were recorded:
19’,
24’,
22’,
18’,
and 16”.
‘Ihe
Aii Traffic Manager of the TRACON testified that the area of unusable
primary target returns near the Seal Reach VORTAC
“was
not an area we had previously
identified.”
He testified that the flight check conducted since the accident had pointed
out a
‘Couple
of areas . . .
where there is a problem with the primary coverage and we
weren’t aware of . . . previously,
Iv
but that the
“beacon
(secondary target) coverage was
good.”
A third flight check of the Los Angeles
TRACON’s
ASR-4 radar was flown on
March 11, 1987, as a result of another reported near midair collision
(NMAC).
On January
31, 1987, Aeromexico
Plight
498 was descending towards
L.
A. International within the
confines of the Los Angeles TRACON. While descending through about 6,400 feet, the
Aeromexico flightcrew reported sighting a
vvCessnavv
to the TRACON. According to the
flightcrew, the Cessna crossed about 2,000 to 3,690 feet in front of and about
‘800
to 500
feetvv
above them, but had not been pointed out to them by the approach controller.
Upon
receipt of the Aeromexico report, the approach controller rechecked his radar display and
stated that the Cessna was not depicted on it.
He summoned another controller to look
for the Cessna’s radar return, and the second controller also stated that he did not see any
radar target on the display in the area where the Aeromexico flightcrew had reported the
sighting.
-25-
Flight 498 continued to descend and landed without further incident; the
flightcrew did not perform any evasive meaneuver to avoid the Cessna.
Subsequent examination of the March 11 recorded radar data confirmed the
Aeromexico
flightcrew’s
report and showed that a code 1200 VFR target had crossed in
front of flight 498; however, no altitude information was available for the VPR target
return.
The recorded radar data, which included only ARTS
RI
alphanumeric data,
indicated that fliiht 498 passed behind the Cessna and that the minumum lateral
separation between the two airplanes ranged from about
3/4
mile to 1
3/8
miles as
compared to the 2,000 feet to 3,000 feet estimated by the flightcrew.
Given flight
498’s
altitude-6,400 feet-and the
flightcrew’s
estimate of the Cessna’s relative altitude, the
Cessna was probably above the
TCA and the estimated vertical separation probably
ranged from 600 to 1,000 feet at the point where the airplanes’ tracks crossed.
Rased
on
these separation distances, the reported NMAC would have fallen within the
FAA’s
“no
hazardvv
category. The FAA has established the following categories for
NMACs:
1.
Critical: a situation where collision avoidance was due to chance
rather than an act on the part of the pilot.
Less than 500 feet of
aircraft separation would be considered critical.
2.
Potential: an incident which would probably have resulted in a
collision if no action had been taken by either pilot.
Closest
proximity of less than 500 feet would usually he required in this
case.
3.
No Hazard: a situation when direction and altitude would have
made a midair collision improbable regardless of erasive action
taken.
Given the fact that flight 498 was near the point where the August 31 collision
occurred, the Safety Board requested the FAA to conduct another flightcheck of the
TRACON’s
radars, which they did on March 11, 1987.
The flightcheck was conducted between 1130 and 1230 in the area just east of
al
Beach
VORTAC. The flightcheck airplane, a Cessna 172, was flown between the
i and
26
nmi DME arc of the Los Angeles VORTAC and the following runs were
1.
At 5,000 feet; heading
090’
i:
At 5,500 feet; heading
270’
At 6,000 feet; heading
090’
4.
At 6,500 feet; heading
270’
5.
At 7,000 feet; heading
090’
The performance of the ASR-4 and ASR-7 radars was checked. However,
five runs on the ASR-7 were flown at the same altitudes as those flown to
SR-4,
they were flown on reciprocal headings. The ASR-4 radar, ARTS III,
were configured as they were at the time of the accident on August 31, 1986,
ard
personnel observed the scoring of both radars’ performance.
With regard to the ASR-4, except for one miss (at 14 nmi from the Los
eles VORTAC at 7,000 feet), all primary targets were usable, either 2s or
3s,
with the
rn~~or~t~
being 3s.
There
was only one unusable secondary target.
-26-
The ASR-7 did not perform as well as the ASR-4 and in two instances; the
combination 1 and 0 scores required the target to be classified as unusable.
Both of these
instances occurred on the outbound run
(0909
at 6,500 feet at about 18.5
nmi
and 20 nmi
from the Los Angeles VORTAC; however, all secondary targets were usable.
The
ASR-7
radar is normally used to monitor and control traffic arriving from the north.
The March 11 sounding showed an inversion between 2,532 feet and 3,920 feet
and the atmosphere was moist from the surface to the base of the inversion. There were
super-refractive layers between 2,148 feet and 2,857 feet; between 7,974 feet and 9,010
feet but over all, there was less refraction than would have occurred on either August
31
or September 3, 1988.
Recorded Radar Data
-
Radar data recorded at the Los Angeles TRACON
during the time of the accident was acquired by the Safety
Beard.
‘Ihe
tapes contain the
data that was sent from the ARTS
III
I/O Processor to the DEDS units in the TRACON.
Since the ARTS III cannot record primary target returns or beacon control slashes, the
recorded data contain only the alphanumeric symbology transported from the I/O
Processor to the DEDS.
The radar data covering the period of time pertaining to the accident were
processed by the Engineering Services Division of the Safety Board’s Bureau of
Technology. The targets of the DC-9 and the Piper recorded by the ASR-4 and -7 radars
were read from the tapes, converted from magnetic to true north, translated into a
common coordinate system, and plots of the paths of both airplanes were made.
Figure
5
shows the beacon targets of both airplanes
for
about the last 3 minutes of their flights.
Based
on this plot, at
1151:17,
the
DC-9
and Piper were about 3 nmi apart; at
1151:36,
they were about 2 nmi apart; and at
1151:55,
they were 1 nmi apart.
The recorded radar data also indicated that the Piper passed the
TCA’s
lateral
boundary about
1149:47
and that the collision occurred about 3 nmi
wast
of that boundary.
‘Ihe
manufacturer’s climb performance chart was based on a
76-KIAS
climb speed.
Between 5,000 feet and 7,000 feet, based on the airplane’s estimated gross weight and the
existing weather conditions, the Piper could have climbed at a rate of about
300
fpm to
350 fpm. Since the collision occurred about
115299
at about 6,560 feet, the Piper
probably climbed through 6,000 feet-the base altitude of this segment of the
TCA-about
the same time it crossed the
TCA’s
lateral boundary,
The AR-1 controller testified that, based on the range setting he had set in his
DEDS, 1 inch on his display equalled about 2 nmi.
1.17.3
Air
Tkaffie
control
procedures
The rules, regulations, and procedures governing the conduct of both ATC
facilities and controllers are contained in numerous FAA publications and orders.
Only
those documents relevant to the facts
and circumstances involved in the collision have
been cited herein.
Paragraph 373b of FAA
Grder
7210.3G,
nFacility
Operation and
Administration,” requires facilities to issue a directive establishing facility standarda for
displaying required transponder replies and the. switch positions required for their
presentations on the radar display.
The
paragraph also states in part that ARTS facilities
shall also prescribe procedures for monitoring mode 3/A codes with the ARTS in either
e
.
.
*
.
*
.
2
.
/
Figure
5i--Beacon
targets of DC-9 and Piper
during last
3
minutes of flight.
-280
the beacon or analog mode.
Gn
March 15, 1984, the TRACON also issued a supplement
(7210.30.
LAXSUPl),
containing the codes to be monitored using the lo-channel decoder.
However, the supplement did not iterate the
TRACON’s
standard procedure of using its
lo-channel decoder for traffic separation procedures instead of the ATCBI-4 decoder, nor
did it state that code 1200 would be inserted into channel 9 of the decoder.
Although the
directive did not state how the 1200 code was to be monitored, the evidence was
conclusive that it was being monitored when the accident occurred.
The AR-l controller% DEDS had been configured in accordance with the
provisions contained in
LAXSUP
1, and he had inserted the 1200 transponder code into the
System Data Area of his DEDS. Therefore, targets on his display were being displayed as
described in Section 1.17.2 above. Based on the setting of his altitude filter, all targets
between 300 feet and 23,300 feet were being displayed.
FAA
Grder
7210.65D,
“Air
Traffic
Control” (hereinafter called the Controllers
Handbook) contains the procedures to be used by ATC controllers. Paragraph 1.1 of the
Controllers Handbook states:
This order prescribes air traffic control procedures and phraseology
for use by personnel providing air traffic control services.
Controllers are required to be familiar with the provisions of this
handbook that pertain to their operational responsibilities and to
exercise their best judgement if they encounter situations that are
not covered in it.
Paragraph 2-2 of the Controllers Handbook states in part:
a. Give first priority to separating aircraft and issuing safety
advisories as required in
-27-
this handbook. Good judgement shall
be used in prioritizing all other provisions of this handbook based
on the requirements of the situation at hand.
b. Provide additional services to the extent possible, contingent
only upon higher priority duties and other factors including
limitations of radar, volume of traffic, frequency congestion, and
workload.
Paragraph
2-2b
contains a note, which states in part:
The ability to provide additional services is limited by many
factors, such as the volume of traffic, frequency congestion,
quality of radar, controller workload, higher priority duties, and
the pure physical inability to scan and detect those situations that
fall in this category.
The AR-l controller testified that the vertical and horizontal separation
minimums between IFR and VFR aircraft in a
termhal
area and within 15 nmi of the
antenna are 500 feet and 1
l/2
nmi, respectively. However, paragraph 5-72 of the
Handbook states that for aircraft within less than 40 nmi of the radar antenna, the
minimum separation is
“3
miles.”
-29-
Paragraph 5-71 of the Controllers Handbook states in part that the controller
shall apply radar separation:
ai
Between the centers of primary radar targets; however; do not allow a
primary target to touch another primary target or a beacon control
slash.
b. Between the ends of beacon control slashes.
c.
Between the end of a beacon control slash and the center of a primary
target.
The manager of the TRACON testified that while the ARTS III-generated
alphanumeric symbology could not be used to separate traffic, he had seen the symbology
used as a basis for issuing a traffic advisory.
The Controllers Handbook defines the circumstances that require controllers
to advise aircraft of traffic. Paragraph 5-8 contains merging target procedures, which
state that controllers shall issue traffic information to those aircraft whose targets
likely to merge unless the aircraft are separated by more than the appropriate
1 separation minima.
‘Ihe
paragraph states in part that this information shall be
ven to
Urbojet
aircraft regardless of altitude.”
Paragraph 2-21 of the Handbook states in part,
“issue
traffic advisories to all
aircraft
(IFR
or
VPR)
on your frequency when in your judgement their proximity may
dimim~h
to less than the applicable separation minima.
tt
The remainder of the paragraph
contains recommended phraseology to describe the relative location of the traffic and its
altitude, and it recommended that controllers use the term “altitude unknown” when no
altitude data is available.
In addition to traffic advisories, the position of traffic could require the
~o~trol~r
to issue a safety alert as prescribed in paragraph 2-6 of the Controllers
raph
2-6 states in part:
Issue a safety alert to an aircraft if you are aware the aircraft is
at an altitude which, in your judgement, places it in unsafe
. .
roximity to . . . 0ther aircraft.
2-6b.
Aircraft Conflict Alert
-
Immediately issue/initiate an alert
to another aircraft if you are aware of another aircraft at an
altitude which you believe places
em in unsafe proximity. If
feasible, offer the pilot an alternate course of a action.
note (Note 1) appended to paragraph 2-6 states that the issuance of a
is a first priority . . .
once the eontroller observes and recognizes a
situation of unsafe aircraft proximity . . . to other aircraft.
Conditions such as workload traffic volume, the quality/limitations
of the radar system, and the available lead time to react are
factors in determining whether it is reasonable for the controller
to observe and recognize such situations. While a controller cannot
see immediately the development of every situation where a safety
alert must be issued, the controller must remain vigilant for such
situations and issue a safety alert when the situation is recognized.
e
so-
Unless a pilot flying pursuant to VFR is cleared by the
.appropriate
controller
for fliiht in either a TCA, a Terminal Radar Service Area
(TRSA),
or an Airport Radar
Service Area
(ARSA)
that provides conflict resolution, VFR aircraft do not receive air
traffic control separation service from controllers. Paragraph 2-2 of the Controllers
Handbook states in part,
“give
first priority to separating aircraft. . .
.”
Since only IFR
aircraft are provided traffic separation services, the controller% first priority is to
separate IFR airplanes from IFR airplanes.
Except for issuing a safety alert which,
pursuant to paragraph 2-2, has the same priority as separating traffic, all other duties fall
within the category of additional services and will be provided subject to the conditions
contained in paragraph
2-2b
of the Controllers Handbook.
lhe
AR-l controller testified that the center or origin of the radar sweep had
been offset
to.
the left side of his display and was located about 5 nmi west of
LA.
International.
‘Ihe
range markers were 5 nmi apart and extended out to 30 nmi from the
center or origin of the sweep.
Given this configuration, the area of coverage on his
display extended about 40 to 45 nmi east of L.A. International and included a video map
showing the horizontal boundaries of the TCA. However, while any radar target that was
inside the horizontal boundaries of the TCA would be displayed within its confines on his
video map, the controller would not know if the target was within the TCA vertical limits
without either a mode C altitude readout or an
:altitude
report from a pilot. The
controller testified that regardless of where a VFR target was located on his display,
workload permitting, he would provide traffic advisories where applicable.
The AR-l controller testified that he had configured his DEDS to display
primary targets and that the primary targets, as presented on his display, were “about the
size of an eraser, maybe two erasers side by side, a standard size pencil eraser.
Not a
pinpoint of light.”
He controlled the brightness of the primary target with the
MT1
(moving target indicator) Normal Video Gain
(MTI/Viieo
Gain) control knob on the control
console of his PVD. He testified that “Generally the
MT1
is adjusted to near its full
intensity.
You adjust to where you get good clear target presentation without
overblooming or out of focus effect.”
Examination of the ATC transcript (see appendix I?) showed that the AR-l
controller had provided three traffic advisories concerning untracked VFR targets to
air lanes under his control within the TCA.
The advisories were issued at
1142:16,
1116:11,
and
1150:39;
none of these reported targets were mode C-equipped. At
1150:46,
the AR-l controller advised flight 498 of “traffic, ten o’clock, one mile, northbound.” As
subsequently shown by the recorded radar data, the target in question was a non-mode C
target displaying a discrete beacon code indicating that it was being controlled by another
facility. With regard to his workload, the controller characterized the traffic as
‘light.”
The AR-l controller stated that he would issue a traffic advisory to an
airplane whenever the traffic
“in
my opinion, will come to a spot where I will have less
than applicable separation.”
He said that he would issue an advisory about any traffic
inside the confines of a T-shape that he
pojected
mentally ahead of the airplane he was
controlling. The vertical bar of the
‘Tn
was projected 3 nmi ahead of the airplane and
along its line of
fIight;
the crossbar of the
“T”
extended 3 nmi either side of the vertical
bar. The controller stated that after flight ,498
,pa,ssed
the traffic he had pointed out at
1150~46,
he did not see any traffic
that
he considered a factor to the continued progress
of flight 498.
The AR-l controller stated that the Piper
“was
not displayed. It is my
belief that he was not on my radar scope.
”
He
t&ified
that if he had seen the Piper, he
would have issued a traffic advisory to fliiht 498.
-31-
At
1151:57;
after instructing flight 498 to maintain its present airspeed; the
AR-I controller asked the
night
to stand by for
%
change in
~Ians.~~
According to the
controller, he had been informed by the traffic coordinator that
night
498 could use
runway 24 right for landing.
At
1151:23,
the AR-l controller answered the initial radio call from the
Grumman Tiger,
N1566R
At
1151:26,
N1566R
informed the controller that it was a
VFR
flight from Fullerton to Van Nuys, that its altitude would be 4,500 feet, and that it was
requesting flight
foIIowing
services. The AR-l controller testified that he did not respond
immediately because at that time the arrival coordinator
“was
informing me that
Aeromexico 498 could have runway
24.
”
The
controller testified that after receiving the
coordinator% message, he began to check the traffic inbound to the airport from the east
to see if he would have any problems inserting
fbiht
498 into the
Ianding
sequence for
runway 24R. At
1151:45,
he instructed flight 498 to “maintain your present
speed.”
He
testified that, between
1151:45
and 1152:00:
when the conversation was going on with Aeromexico, and I was
attempting to get him to maintain his present speed...At that point
in time I looked over to the AR-2 scope (the AR-2 display is
located next to his display) to see what possible traffic they might
have for Aeromexico to see if the speed difference was going to
make any difference in his sequence into Los Angeles.
With regard to the appearance of
N1566R
on his frequency at
1151:18,
the
controller testified that although he did not respond immediately after receiving
N1566R’s
request for flight following, he was aware of his route of flight and requested altitude
en route to Van Nuys.
The
controller testified:
At this point in time his response indicated to me that if he were
not in the TCA already, he would probably be on a course of flight
that would place him there very shortly and at an altitude that
would
place him in the middle of the TCA. (Except for two very
short segments, the floor of the TCA along
N1566R’s
stated route
of
flight
was
essentiaIIy
either 2,000 feet or 2,500 feet.) I can
recall scanning along the line of
flight
from Fullerton up towards
Van Nuys to see if I had any targets indicating 4,500 feet that
might possibly be six six Romeo.
tified that since
N1566R’s
message did not mention the TCA, since the
tude was above the floor of the TCA, and since the pilot did not say that he,
cIear
of the TCA,
9t
was just my professional opinion at that time that he
my airspace.” The recorded ARTS III keyboard entries also showed that, at
116187,
the AR-l
controlIer
inserted the
N1566R
indentification
into the ARTS III to
tain a discrete
VPR
code to assign to the airplane.
At
1152~64,
the AR-l controller told the
N1566R
pilot to set 4524 in his
At
1152:14,
Nl566R’s
beacon return was acquired automatically by the
however, the controller did not contact
N1566R
until
1152:29.
At that time,
was
about 15 nmi east of
L.A.
International, climbing through 3,400 feet, and
A.
(See
figure
1.)
The AR-l controller testified that when he saw
N1566R’s
it
“became
my primary duty to resolve what was a potential conflict
tween six six Romeo and Wings West
5083.”
He testified that about
1152~36
the computer was no longer tracking
flight
498. He made two further
t were unacknowledged to the flight and then saw:
-32-
1 had lost (flight
498’s)
primary target; At that point I notified the
arrival coordinator that I had lost radio contact with Aeromexico
498 and shortly thereafter notified him that
I
had also lost radar
contact with Aeromexico
498.”
L17.4
Terminal Control Areas
The FAA introduced
TCAs
and other air traffic control measures aimed at
reducing midair collision potential during the early
19709
after a series of midair
collisions involving 12 air carrier aircraft.
Since 1972, two midair collisions involving air
carrier aircraft have occurred in terminal areas:
the collision over Cerritos and a
collision over San Diego on September 25, 1978, between a Pacific Southwest Airlines
Boeing
727 and a Cessna 172 (NTSB-AAR-79-S). No TCA existed at San Diego when the
Pacific Southwest Airlines collision occurred; consequently, the Cerritos midair collision
was the first to occur within a TCA.
Presently, 23
TCAs
are in existence: 9 Group I
TCAs
and 14 group II
TCAs.
(Group I and II classifications are based on the volume of traffic and the number ‘of
passengers
enplaned
annually at the
TCA’s
primary Airport.)
Each
TCA includes one
primary airport and these 23 airports are among the busiest of all terminals in aircraft
operations and passengers carried. During 1984, TCA hub airports handled about 18
pecent
of all aircraft operations reported at FAA control towers and about 64 percent of
the
enplaned
passengers in the United States.
A TCA is a region of airspace surrounding large air transportation hubs within
which a combination of regulatory airspace operating rules and air traffic procedures are
used to reduce the midair collision potential.
These
high density terminal areas contain
complex air traffic conditions due to the mix of aircraft present and their wide range of
performance characteristics.
Under these traffic’ conditions, separation between aircraft
cannot be ensured if unauthorized transient aircraft
proceed
through the area at altitudes
used by arriving and departing aircraft.
Thus, appropriate regulations require
authorization from ATC prior to the operation of an aircraft within the
TCA
In addition
to requiring ATC authorization before entering these
TCAs,
14 CFR Part 91.90 levies
additional procedural and airplane equipment requirements as a prerequisite for operating
within group I and group II
TCAs.
The group I requirements are as follows:
1.
A VHF
Omni-directional
range
(VOR)
or Tactical Air
Navigation
(TACAN)
receiver
‘(except
helicopters)
2.
A two-way radio capable of communicating with
ATC
3.
A
4096
code transponder with mode C altitude reporting
equipment
’
*
4
A private pilot certificate to land or take off from an airport
within the TCA
5.
Unless otherwise authorized by ATC, each person
operatjng
a
large turbine powered airplane to or from the primary airport
shall operate at or above the designated floors while within
the lateral or vertical confines of the TCA.
-33-
Except for the following two provisions, the requirements for operation within
a group II TCA are identical to those above:
1.
A mode C altitude reporting capability is not required;
however, beginning December 1987 it will be required.
2.
Student pilots are permitted to take off and
Iand
from
airports within the TCA.
After the Cerritos collision, the FAA examined the NMACs received from
pilots during 1984 and 1985. During this period, 295 NMACs (22 percent of the total filed)
occurred in or near
TCAs.
Of these, 95 occurred inside a TCA; 26 occurred in airspace
underneath a TCA; 14 occurred above a TCA but below 12,500 feet; 53 occurred outside
TCA airspace but within 30 nmi of the
TCA’s
primary airport; and 107 occurred in Airport
Traffic Areas or at non-towered airports underneath or just outside TCA airspace.
Since these data indicated problems within or near
TCAs,
the Administrator of
the FAA convened a TCA Review Task Group on September 16, 1986, to study the
effectiveness of the TCA program. The work of the group was divided into three principal
areas:
A.
TCA Airspace Enforcement Issues
B.
TCA Concept and Design Issues
C.
TCA Educational Issues.
The Task group completed its work on October 15, 1986, and according to one
of its task group commanders, submitted about 40 recommendations to the Administrator.
n October 30, 1986, after reviewing the group’s recommendations, the Administrator
accepted
39 recommendations and ordered that the FAA act to implement them
(appendix
G).
The adopted recommendations included proposals designed to simplify and
standardize the lateral and vertical boundaries of the
TCAs;
proposals designed to
enhance enforcement procedures and to increase the penalties imposed upon pilots who
intrude into TCA airspace; and a proposal to require aircraft flying within 30 nmi of the
TCA airport to be mode C-equipped and to use the mode C equipment.
On June 11, 1987, the FAA issued a Notice of Proposed Rule Making
(NPRM),
Terminal Control Area
(TCA)
Classification and TCA Pilot and Equipment Requirements,
which described rulemaking which would implement those action items for TCA
simplification and enhanced mode C requirements. A single class TCA design would be
established and is described generically to include an area encompassed by three
concentric
circles, the innermost with a radius of
19
nmi from surface to 12,500 feet; the
second with a radius of 10 to 20 nmi from an altitude of approximately 3,000 feet to
feet; and the third with a radius of 20 to 30 nmi from an altitude of 5,000 or 6,000
Q
12,500 feet. The mode C transponder would be required for all aircraft operating
the surface upward with 30 nmi of the major airports within the TCA. The
king would apply to
alI
23 sites presently having a TCA. Additionally, the NPRM
amble indicates that nine more airports would meet the criteria for a TCA.
-34-
With regard to the enforcement of the regulations that protect the airspace of
the
TCAs;
the task group
found,that
most
TCA.incursions
were not being reported by Air
Traffic or others as violations. In some
.cases,
the controller in contact with, the pilot
simply
tea
him he is in violation and issues a corrective instruction.
However, in many
cases, the intruding aircraft is not noticed or is not recognized as being in the TCA
because:
1.
The controller in a high traffic environment may be too busy to
monitor traffic he is not working or to report the violations he does
observe.
2.
Many violations are either primary targets or VFR beacon targets
without altitude readouts and the controller generally cannot
determine that the airplane is operating within the vertical
confines of the TCA.
3.
Many, if not most, violations observed by the ATC controllers are
not referred to FAA flight standards offices for enforcement
because the aircraft and/or its pilot cannot be identified.
Additional, as well as corroborative, evidence of problems in this area was
elicited by the Safety Hoard during its investigation and during the public hearing. The
AR-l controller testified that, with regard to TCA intrusions, the number varied and
‘it
could be anywhere from zero to 10 or 15 a shift that I will observe.”
The Air
Traffic
Manager of the Los Angeles TRACON stated during an
interview that between April 1985 and the time of the accident, the facility had noted 23
TCA incursions. At the public hearing, the Air
‘Traffic
Manager testified that between
the time of the accident and December 2, 1986, the facility had filed 32 incident reports
%nd
the majority of those were TCA violators. . .
.‘I
He further testified that this
increase did not occur
rrautomatically.
”
After the accident, the facility had increased the
“emphasis on tracking them (TCA intruders).”
Pursuant to FAA procedures, the TRACON forwarded these cases to the Los
Angeles Flight Standards District Office
(FSDO)
for further processing and enforcement
action.
The
manager of the Los Angeles FSDO testified that, as of December 2, 1986, the
FSDO had processed “almost 200 enforcement
actionP
of all types. With regards to TCA
violations received from the Los Angeles TRACON, between January 1, 1986, and
December 2, 1986, the FSDO had received about 38 to 40 violations for processing; 32 of
these had occurred after the accident.
The FSDO manager testified that processing of enforcement investigation
“has
second priority behind accident investigation” in his office. He testified that
“next
to
some problems regarding chain of evidence, I would say that pilot identification is the
foremost problem in the prosecution of a pilot deviation, TCA, or otherwise.” He added,
Chain of evidence usually refers to handoffs where the aircraft is
being tracked from one sector to another, (or) maybe from one
facility to another, and we have to provide a chain of evidence to
(prove)
l . . that we’re talking about the same airplane.
With regard to the FSDO workload, he testified that in order to process cases
at the rate of 10 to 11 per month, the rate that existed since the accident, it would be
necessary to curtail some of the other FSDO workloads.
-35-
w.5
Traffic Alert and Collision Avoidance
-terns
Between 1955 and 1965; most research to develop airborne collision avoidance
systems was conducted by aviation or aviation-related corporations such as McDonnell
Douglas, Minneapolis Honeywell, and Radio Corporation of America (RCA).
Each of these
corporations produced collision avoidance systems; however, these systems did not work
unless both airplanes had identical equipment of the same technology.
About
1974,
the
FAA began a parallel investigation of the possibility of using the existing air traffic
control transponder as an element in an airborne collision avoidance system. Research
and investigation based on the development of a system using the transponder continued
and resulted in the development of the
Traffic
Alert and Collision Systems
(TCAS)
I, IL
and IIL The three systems are designed to provide reliable aircraft separation, based on
time, not distance, from other transponder-equipped aircraft. TCAS has three levels of
sophistication.
The simplest and least costly level, TCAS I, will alert the pilot by using
visual and, or aural alerts when other aircraft are close; however, it will not provide
resolution advisories to the pilot.
General aviation pilots are expected to be the principal
users of the TCAS L
TCAS II is designed to provide reliable aircraft separation from other
transponder equipped aircraft in traffic densities as high as 0.3 aircraft per square
nautical mile (24 transponder-quipped aircraft within 5 nmi of the TCAS II-equipped
aircraft).
The
TCAS II equipment in the aircraft interrogates transponders and altitude
encoders on aircraft in its vicinity and listens for transponder replies.
By
computer
analysis of these replies, the TCAS II equipment determines which aircraft represent
potential collision threats and provides appropriate aural and visual display indications (or
advisories) to the flightcrew to ensure separation.
When the TCAS II computer determines that an aircraft is a threat, it
nerates a symbol representing the intruder on either the aircraft’s weather radar display
a cathode ray tube designed to present this information. The computer then provides
range and bearing information about the intruder.
This information is generally displayed
when the aircraft are about 40 seconds apart.
If the intruder is mode-C equipped, its
relative altitude to the receiving airplane is also displayed next to its symbol.
If the
threat persists, the pilot receives a resolution advisory 15 seconds later (about 25 to 30
seconds before the predicted time of closest approach).
A red light illuminates and the
vertical resolution advisory-the best climb or descent maneuver the pilot could take to
void this intruder--is given to the pilots orally and pictorially on his vertical velocity
or.
The oral advisory can also be in the form of preventative commands, i.e.,
don’t
don%
descend.
If the intruder is not mode C-equipped, question marks are displayed in place,
of the relative altitude next to the intruder symbol, and range and bearing information are
displayed.
If the threat persists, the TCAS II system does not provide a resolution
advisory. About 25 to 30 seconds before predicted time of closest approach, the red
light
iRuminates
and the range and bearing of the intruder continues to be displayed, thus
indicating to the flightcrew where they are to search visually to locate the intruder.
The TCAS III, the most sophisticated of the TCAS family, is almost identical
to TCAS II except that TCAS III provides flightcrews with both horizontal and vertical
re~ol~t~o~
advisories. Because the TCAS III provides horizontal resolution advisories, it is
d
with an improved beacon antenna that provides more accurate bearing
information to the TCAS computer.
The improved beacon bearing information also
reduces the number of unnecessary alerts.
However, with regard to the efficacy of the
vertical escape maneuver, the Manager of the
FAA’s
Aircraft Engineering Division of the
-36-
Office of Airworthiness testified that they had never seen an encounter that could not be
handled with the vertical maneuver.
1
do agree that the
horizontal maneuver adds a third
dimension which in some cases might be more desirable, but as far as it will handle it, the
vertical maneuver will do the
job.”
lhe
Manager of the
FAA’s
Airborne Collision Avoidance and Data Systems
Rranch
testified that the FAA had recreated the Cerritos collision geometry to test the
performance of the TCAS III system.
He testified that since the intruder was not mode
C-equipped, it made no difference which system was used since neither system could
supply a resolution advisory. During the test, the TCAS provided a solid traffic advisory
“from
a point between thirty and forty seconds to the time of closest approach.”
The
manager compared the traffic advisory provided from the TCAS to that provided by an
ATC controller. He testified
it (the TCAS alert) would be like the best traffic alert you ever got
in your life, plus, it stays on the whole time.
It&.&most
another
magnitude better in the information it conveys to you than air
traffic control can normally do.
Although the FAA has been flight testing TCAS III since 1983, it has not been
certified and further testing is still needed. However, three U. S. Air Carriers have either
begun, or will begin, to fly the TCAS II in Limited Installation Programs (LIP).
(%
March
18, 1987, Piedmont Air Lines began evaluation flights with a Sperry Dalmo Victor TCAS II
installed on one of its Hoeing 727s.
As of July 6, 1987, the system had accumulated 280
hours.
It has provided 220 cautions and 21 warnings. With regard to responding to
resolution advisories during this program, the FAA requires the Piedmont pilots to acquire
the intruder visually before performing the advisory’s requested maneuver.
‘Ihe
Piedmont
LIP is scheduled to begin in early September.
United Air Lines is scheduled to begin its LIP in November 1987, with Bendix
TCASIIs
installed on two airplanes: a McDonnell Douglas DC-8 and a Boeing 737.
Northwest Air
Lies
is scheduled to begin its LIP in October 1987 with a Sperry Dalmo
Victor TCAS
IIs
installed in two McDonnell Douglas MD-80 airplanes.
On
May 8, 1987, the FAA stated that they intended to initiate an NPRM
which, if adopted, will require that air carrier aircraft be equipped with a TCAS.
1.18
New
hvestfgative
?Ikdmiw
lel&l
Retrack
program
r
The
Retrack Program Computer at the
PAA
Technical Center, Atlantic City,
New Jersey, can demonstrate almost every aspect of the ARTS III computer program.
The retrack program can, through the use of recorded data, recreate the ARTS III
alphanumeric symbology shown on a controller’s display for the data recorded.
However,
the retrack program cannot display either raw radar returns (primary targets, ground
clutter) or analog beacon control slashes since this information is not recorded.
Thus, the
retrack program cannot replicate the entire radar portrayal on a controller’s display; it
only replicates the alphanumerics generated by the
,ARTS
III program and its associated
logic aspects.
Cn
March 4, 1987, the data recorded by’the Los Angeles
TRACON’s
ARTS III
I/O Processor for the time immediately before and-including the accident were inserted
into the
FAA’s
Retrack Program Computer.
The Retrack Computer had been
-37-
programmed with the Los Angeles
TRACON’s
ARTS
III
program; control settings on the
test DEDS replicated the control settings used by the AR-l controller on the day of the
accident. The inserted data produced the alphanumeric symbols generated by the ARTS
RI
for both flight 498 and the Piper PA-28, and their tracks were similar to those
contained on figures 3 and 4. In addition to these two airplanes, the alphanumeric symbols
of other airplanes generated by the ARTS III radar were shown, however, the reproduced
display did not show primary targets, beacon slashes, video maps, or any ground clutter
that might have been displayed on the AR-l controller’s PVD at the time of the accident.
The plot of the alphanumeric target symbols contained on figure 4 showed that
the target symbols of both accident airplanes were being displaced back and forth in
azimuth
&titchingr)
as they proceeded toward the collision point.
‘Ihe
amount of the
lateral displacement, when measured angularly at the beacon radar antenna, was about
2’
to
39
This
%titchingrr
movement was visible on the display produced by the Retrack
Program. The ARTS III specialists at the Technical Center stated that the
%titching”
was
caused by distortion of beacon code replies from the interrogated transponder.
The
distortion could be produced by overlapping beacon replies from two or more airplanes or
by deficient suppression of the side lobes of the beacon interrogation signal from the
beacon antenna at the radar site. The improper side lobe suppression
UJ
could be the
result of a hardware problem or misadjustment.
A deficient side lobe suppression allows
the beacon interrogation and response to continue for a longer portion of the beacon
tenna sweep. Thus, the received beacon signal will subtend a longer than normal arc at
range on the controller’s display.
The ARTS III computer places the
ic
target symbol at the computed centroid of the received beacon train.
If a
the
beacon’s response is garbled by
inteference
with other airplanes’ beacon
ls,
the portion of the beacon which is not garbled will appear as a good and full
beacon train and the centroid will be offset.
ANALYSIS
2.1
GBMERAL
Roth airplanes were maintained in accordance with all applicable regulations
and, with regard to the
DC-g,
company procedures. There was no evidence that any
lane
malfunction contributed to the collision.
The captain and first officer of flight 498 were certificated properly, trained,
to perform their assigned duties.
‘Ihere
was no evidence of any preexisting
or psychological disability that would have decreased their abilities to
inflight
duties.
beacon antenna is
colocated
and ates with the ASR radar antenna and
s an interrogation signal to which
ai
rne transponders reply. The antenna is
SQ
that the main lobe of the interr
n
signal is concentrated in the direction
and limited in width so that it subtends a small arc during any
rotation.
The
interrogation signal also contains side lobes of
the main lobe. To prevent the airborne transponder from replying
signal,
the beacon
antenna also transmits a control signal. The
amplitude of the interrogation signal and control signal is adjusted so that only in
red arc of interrogation (main lobe of the interrogation signal) is the amplitude of
tion
signal greater than the amplitude of the control signal. The airborne
will reply only when the interrogation signal is dominant.
-38-
The pilot of the Piper PA-28 was properly certificated and qualified to
conduct the intended flight to
Bi
Bear.
There
was no evidence of any preexisting
psychological disability that would have &creased his ability to conduct the intended
flight; further discussion of preexisting physiological conditions that could have affected
the conduct of the
fliiht
is contained in a later section of this analysis.
The
AR-l controller was certified,
tratied,
and qualified to provide the
required ATC service.
There was no evidence of any preexisting physiological or
psychological disabilities that would have decreased his ability to perform his required
duties.
The
evidence was conclusive that the collision occurred within the Los Angeles
TCA; that the Piper pilot had entered the TCA without having been cleared to do so; that
the AR-l controller did not advise flight 498 of the position of the Piper; and that neither
pilot tried to perform any type of evasive maneuver before the collision.
Given these
data, the major thrust of the Safety Board’s analysis
.was
to identify those factors that led
to the events cited above and the resultant collision.
292
The
Accident
Collision Geometry-The
collisioip
occurred as flight 498 was descending
through about 6,660 feet.
Ihe
radar data
shmed
that the DC-9 was on a northwesterly
track and the Piper
ori
an eastbound track that traversed the DC-9 track from left to
right.
The
collision damage on the DC-9 was confined to its vertical and horizontal
stabilizer.
Although much of the structure of the DC-9 forward of the empennage was
consumed by fire, there was no evidence of midair collision damage on those pieces of
structure that were not consumed by the fire.
The
damaged areas on the DC-9 vertical and horizontal stabilizers contained
propeller slice marks, paint transfer marks Rom the nose wheel area and vertical
stabilizer of the Piper, and embedded pieces from the cabin roof area of the Piper.
The
location and angles of these marks and damage on the
DC-g,
when matched to their
respective locations on an intact Piper PA-28, showed that the front of the Piper had
struck the left side of the DC-9 vertical stabilizer and that the impact angle was
perpendicular to the longitudinal axis of each airplane. (See figure
6.1
The impact angle
was generally consistent with the flight tracks of the airplanes shown on the radar data
plots.
‘Ihe
absence of any impact marks or damage on those portions of the DC-9
left wing and fuselage forward of the empennage that had not been consumed by fire and
the damage to the DC-9 vertical and horizontal stabilizers, showed that the PA-28
airplane was about 8 to 10 feet above the top of the
DC-S%
fuselage and about 15 to 17
feet above its wings when the collision occurred.
“Ihe
damage also indicated that the
longitudinal axis of the Piper was almost level at impact and that the initial impact was
-with the DC-9 vertical and horizontal stabilizers.
The
debris
from
the Piper cabin roof,
embedded in the leading edge of the DC-9
horizontalstabilizer,
and the fact that the roof
of the Piper was sheared off at about the same height on both sides of its fuselage,
confirmed the fact that the
DC-S%
horizontal stabilizer struck the top of the
Piper’s
fuselage and that the Piper was in the almost wings-level attitude at impact.
(See
figure
7.)
-39-
Estimated
positions
of
aircraft
at impact,
based
on
propeller
damage
to
the
leading
edge
of
the
DC-9
Vertical
Stabilizer.
Mid-Air
Cell:
rion
Between:
Aeromexico,DC-9,Flt
498
&
Piper,PA-28-lSl,N4891F
Location:
Cerritoe,
Ca
Date:
August
31,
1986
Attachment
III
Page
1
of
2
F
e
6.--Collision
geometry as viewed from above the
DC-S
-4O-
Estimated positions of aircraft at
impact, based
on
the propeller
damage
and scratch marks
on
the DC-9 Vertical
and Horizontal Stabilizers.
Mid-Air
Collirion
Between:
Aeromexico,DC=9,Flt
498
&
Piper,PA-2E=lBl,N4891F
Location:
Cerritoe,
Ca
Date:
Auguri:
31, 1986
Attachment III
Page 2 of 2
Figure
'I.--Collisiongeometryasviewedfrom
in frontofthe
DC-g.
-41-
Even though the Piper was a much smaller and lighter airplane, its engine, a
relatively massive object, struck the DC-9 horizontal stabilizer’s main support structure,
causing
it to fail and the horizontal stabilizer to separate. Longitudinal control and
stability was lost when the horizontal stabilizer separated and further controlled flight
was impossible.
Survival Factors
-
Plight
498 fell to the ground from about 6,560 feet and the
oecupiable area of the airplane’s cockpit and passenger cabin was destroyed by massive
impact forces and postcrash fire. Although the occupants of the DC-9 survived the midair
impact, this was an unsurvivable accident for the passengers and crew because of the
massive ground impact forces.
The
DC-S’s
horizontal stabilizer sheared off the top of the Piper’s cabin and its
,leading
edge contained embedded pieces of human remains and hair along with pieces of
the
Piper%
cabin
roof. The evidence showed that the three occupants of the Piper were
injured during the initial impact and that the injuries were not survivable.
The crash, fire, and rescue units involved in the response performed in a
timely and efficient manner. The accident occurred at 1152; the alarm was received at
1153; units were dispatehed at 1154; and the first vehicles arrived at the scene at 1158.
addition to the units described above, local law enforcement units were on the scene
within
6
minutes after the accident.
The crash scene fire was contained within
30
minutes after the first fire engines arrived and was extinguished 35 minutes later.
Siiee
the Piper pilot entered the Los Angeles TCA without an ATC clearance,
fety Board sought to determine if the entry had been deliberate or inadvertent.
The occurrence of a myocardial infarction (heart attack) is disclosed during an
autopsy examination by areas of dead or dying coronary tissue caused by the obstruction
of
e
bb
vessels. Although the data contained in the Piper pilot’s autopsy protocol did
not contain any evidence of this type of tissue damage and thus showed that he had never
heart attack, medical authorities agreed that it was beyond current medical
to determine from autopsy evidence whether the pilot could have experienced
al infarction during the time immediately preceding the collision. For the area
me~roti~
tissue produced by a myocardial infarction to appear in an autopsy, the
arction
would have had to occur at least 12 hours before death. Given these facts, and
ting moderate to severe arteriosclerosis found within the blood vessels of the
pilot’s heart, the Safety Board sought to determine if the pilot had suffered a
ing
heart attack and, thereafter, entered the TCA inadvetently.
The Piper pilot had no history of heart problems and had passed his
Electra
h
(EGG)
tests on every previous
physical
examination (including a resting ECG 8
fore the accident). Even in the highest statistical risk categories for his age,
ity that the Piper pilot would experience a fatal heart attack was
nually
g/.
n, T.;
Morelo@k,
L.;
Muscatel,
MS.;
and Kannel, W.B. (1984). ‘The
Unexpected Death:
Risk Factors for Men and Women in the
y.
American Heart Journal
107,
1300-1306.
-42-
The recorded radar data showed that the Piper PA-28 pilot proceeded almost
directly to the collision point after he took off from Torrance.
Based
on the time the
Piper PA-28 left Torrance--about
11411
the airplane’s rate of climb from takeoff to
impact averaged about 550 fpm. Based on the three flight simulations, this average climb
rate was within the airplane’s performance capability. In addition, the recorded radar
data of the Piper’s progress does not contain any type of dramatic disturbance of either
heading or groundspeed that might be expected if the pilot had experienced a disabling
heart attack.
Rxqept
for a couple of small turns, the fact that the airplane maintained an
almost constant heading and groundspeed indicated that its progress was being monitored
and managed.
In
addition, if a
disabling
heart attack allowed the Piper PA-28 to enter the
TCA and climb to the
6,560-foot
collision altitude, given the average 550 fpm rate of
climb, the pilot had to be disabled at least 2 to 2
l/2
minutes before the accident. Based
on his proposed route of flight and assuming that the pilot was still alert, the last
available proper VFR altitude for fliiht below the floor of the TCA was 5,500 feet.
‘Ihe
Piper would have reached 5,500 feet 1 minute before entering the TCA and 2 minutes
before reaching the collision altitude.
Since the pilot did not level off, the Safety Board,
if it is to accept the hypothesis of a heart attack,
must conclude that the pilot was
incapacitated before the Piper reached 5,500 feet and that the airplane itself maintained
a constant heading and climb rate for more than 2 minutes.
The
Safety Board believes
that it would be improbable for the airplane to maintain a constant heading and climbing
flightpath unassisted by lateral and longitudinal control corrections.
‘lhe
Piper pilot’s primary flight instructor stated that the pilot used the “wing
leveler” when looking at maps or charts, or when doing other in-cockpit activities.
Had
the “wing leveler” been engaged at 5,500 feet and the pilot disabled, the airplane would
have maintained heading and, depending on how accurately the pilot had trimmed out the
elevator forces to maintain the climb rate, could have reached collision altitude
unassisted. However, the recorded radar data showed two turns in the Piper airplane%
track. About
1148:14,
a left turn that corresponded to about
5’bank
was started. The
turn lasted about 20 seconds and, thereafter, the airplane returned to wings-level flight.
‘Ihe
second, a slight turn to the right corresponding to a
5’bank,
began at
1149:50
and
ended about
115085
when the airplane was again returned to wings-level flight.
At the
end of the second turn, the airplane would have
cli-mbed
to about 5,500 feet.
‘Ibe
data
from the flightpath seem consistent with the control inputs of a conscious pilot.
Two additional points bear on this issue. First, there is no evidence that an
emergency radio call was made from the Piper. Second, the occupants of the Piper were
found in the wreckage with their seatbelts fastened. If the pilot had suffered a major
medical problem, the Safety
Roard
believes that one or both of the remaining occupants
would have unfastened their seatbelts and possibly the pilot’s
seatbelt
while attempting to
assist him.
‘Ihe
evidence points strongly to the fact that there was no disturbance in the
cockpit and that the flight was proceeding
normaRy
when the collision occurred. The
Safety Board concludes that the weight of the evidence showed that the pilot of the Piper
did not suffer a heart attack and that the Piper’s entry into the Los Angeles TCA was not
caused by any physiological disability of its pilot.
Althou
h the pilot of the Piper had flown about 5.5 hours in the Los Angeles
area, the Safety
&
ard could not establish the routes of those
flights
and therefore how
familiar he might have been with the boundaries of the TCA in the vicinity of Long Beach
and the Seal Reach VORTAC. However, the pilot was not a total stranger to the Los
Angeles TCA and his discussions with other pilots demonstrate that he was well aware of
the flight procedures required either to enter the TCA or to avoid it.
‘Ihe
pilot discussed
the route to Big Bear with another pilot, who advised him on how to stay out of
-43-
the
TCA,
This pilot was intimately familiar with the
area’s
freeway complex and relied
on these underlying highways as landmarks to denote the geographical boundaries of the
various segments of
t.h.9
TCA and resultant altitude requirements. In their discussion of
the route to Big
ar,
this pilot mentioned using freeways to stay clear of the TCA;
however, the pilot of the Piper was not as familiar with these freeways and therefore
might have used the wrong freeways instead of relying on the more prominent
checkpoints, such as Disneyland and the Anaheim Stadium, to identify his position in order
to
eomtrol
his altitude and avoid entering the TCA.
The pilot of the Riper was described as methodical and professional in his
approach to flying, and as a pilot, more inclined to navigate by visual reference to the
ground than to use navigational radio aides.
The fact that he tried to obtain advice
concerning the Los Angeles area and the TCA before the flight and had purchased a Los
Terminal Area Chart, which was found opened in the cockpit wreckage, tend to
this assessment of his approach to flying.
Given these facts, the Safety Board
believes that it is extremely unlikely that he would intrude deliberately into the TCA. In
the absence of any positive evidence to the contrary, the Safety
Roard
concludes that the
pilot intended to avoid the TCA but that he probably misidentified his navigational
checkpoints and entered the TCA inadvertently.
The
entry of the Piper pilot into the TCA stripped his airplane and flight 498
f the
precise
protection the TCA was designed to provide. Its entry into this prohibited
eated
an exposure to risk that should never have existed and, therefore, the
rd believes that the intrusion into the TCA was a causal factor in the ensuing
fore the accident, the Los Angeles TRACON forwarded TCA intrusion cases
eles FSDO for enforcement action at a rate of about one per month; after
the accident, the rate increased to about 10 per month. The pre-accident rate may be
indicative of the difficulties involved in detecting, tracking, and identifying a TCA
intruder cited in the TCA Task Group’s report to the Administrator. However, the
post-
accident increase in the rate under the same conditions that existed before the accident
ates a less-than-efficient pre-accident effort by personnel in the Los Angeles
CON to detect and identify TCA intruders.
In addition, the TCA Task Group’s report
concluded that, nationwide,
“many,
if not most, violations observed by the FAA are
d for enforcement action because the aircraft and the pilot involved cannot be
1
The Safety Board believes that if the
TCAs
are to continue to provide the
e designed to provide to the aviation community, the FAA must ensure
eons
supporting this protected airspace are well known within that .
most important, that it can and
will
enforce these regulations. The
ieves
that the recommendations in the Administrator’s TCA improvement
in effect promptly and executed properly, will inform the aviation
community
of the
FAA’s
intent to maintain and enforce the integrity of the TCA airspace.
e evidence indicated that the Piper pilot was aware of the Los Angeles
use, and the need to avoid it. Since there is no
defiance of the prohibitory provisions of the relevant
des that the enforcement efforts of the Los Angeles
was not
a casual factor in this accident.
-44-
Without mode C altitude information; the AR-l controller could not determine
whether VFR code 1200 targets displayed within the horizontal boundaries of the TCA
were within its vertical limits and, therefore, actually within it.
Although he could
assume that since these targets had not been cleared to enter they were not in the TCA,
and therefore, not a factor to the airplanes under his control within the TCA, he testified
that he would not make that assumption. He testified that, workload permitting, he would
provide a traffic advisory concerning any target he considered to be a factor to any
airplane under his control and, thus, had he seen a VFR code 1200 target at the Piper’s
location, he would have provided a traffic advisory to flight 498.
He testified that he did
not provide that advisory because the Piper’s target
“was
not displayed,” and further that
it was his “belief that he was not on my radar
scope”.
Therefore, the Safety
Board
sought
to determine what targets, if any, were displayed on the AR-l controller’s display at the
time of the collision, and especially whether the Piper radar target was displayed.
‘Ihe
evidence showed that an overloaded ARTS III computer will not display
targets in excess of its display storage capacity. As a display overload condition occurs,
the computer will print out messages announcing it is overloaded and identify the types of
targets it is not displaying. None of these messages were printed at or before the time of
the accident, nor any message that the computer was within 85 percent of its tracking
capacity.
In addition, none of the
TRACBN’s
controllers reported the occurrence of
wfllckertl,
which indicates the onset of display overload.
The
evidence was conclusive
that, during the time interval encompassing the collision, the ARTS III computer was not
overloaded and was still placing target data into its tracked and untracked target buffers.
Of greater significance is the fact that there was no aspect of the ARTS III computer
hardware or software that would
supress
the display of a tracked or untracked target from
the controller’s displays.
‘Ihe
recorded radar data showed that beacon returns for both flight 498 and
the Piper had been received, processed by the ARTS III Data Acquisition System,
processed by the ARTS III computer, and presented to the display. When recorded radar
data were inserted into the Retrack Program Computer, which was programmed to
perform the functions of the Los Angeles
TRACON’s
I/O Processor, the alphanumeric
symbols representing the Piper and flight 498 were reproduced on the display. Since the
DEDS used during the retrack test was configured as was the AR-l controller’s DEDS at
the time of the accident, the alphanumerics presented on the retrack display were
identical to those that would have been presented on the AR-l controller’s display.
‘Ihe
AR-l controller testified that numerous other VFR code 1200 targets were on his display
at the time of the collision and the Retrack Program Computer displayed what were
probably these targets. Since there was no functional way the AR-l controller could have
selectively removed any one of several VFR targets from his display, and since there was
no functional reason why targets that have been processed by the I/O Processor for
display would not be displayed, the Safety
Board
concludes that the alphanumeric data
recovered from the recorded radar data tapes were displayed on the AR-1 controller%
display at the time of the accident.
The Retrack Program also duplicated the
%tit6hingt1
movement of the targets.
When the progress of the Piper’s target and flight
498%
target across the retrack display
was monitored, it was obvious that, regardless of
%titching,”
their proximity to each
other would have required the controller, had he observed them and had workload
permitted, to issue a traffic advisory to flight 498. Since the
Sa’i’ty
Board has concluded
that, at the least, the alphanumeric symbology denoting the location of the Piper was
displayed on the AR-l controller% display, the Safety
Board
therefore sought to determine
why the AR-l controller did not observe the
Piper’s
target.
-46-
tunnel or narrow their perception or attention.
Under high workload situations, it has
been demonstrated repeatedly that the operator will focus on the primary or
ttprioritytt
tasks, and his attention to secondary tasks will deteriorate.
g/
While in this case, the AR-l controller’s total workload was neither
numerically large nor did it suddenly increase significantly, the change of runways for
flight
498,.
coupled with the sudden appearance of
N1566R,
required a shift in his focus of
attention and brought additional airplanes for consideration into his separation tasks. In
addition, his admonition at
1X2:36
to the pilot of
N1566R
concerning his intrusion into
the TCA seemed to indicate that the controller was annoyed by the additional tasks
imposed on him by the abrupt intrusion.
Consequently, evidence indicates that the
controller’s scan of his display was focused almost exclusively on an area that did not
include the location of the Piper’s target. The Safety Board concludes that this may have
been why he did not see the Piper’s radar target.
The ATC Handbook required the controller to “give first priority to separating
aircraft
. . .
.‘I
Therefore, except for certain participating VFR aircraft, the major amount
of the controller’s traffic separation duties were directed to IFR aircraft which had been
assigned appropriate discrete transponder codes and had presented on the
entroller%
display a full data block in addition to their primary radar returns, beacon control slashes,
and appropriate alphanumeric symbols. Furthermore, even participating VFR aircraft
would have been assigned an appropriate discrete VFR transponder code, indentified in the
ARTS III computer for tracking, and, thus even these aircraft would have presented more
data on the controller% display than an untracked code 1200 VFR target.
(N1566
was
handled in this manner.) The Safety Board. believes that the priorities placed on the
controller to provide traffic separation to these type aircraft could have lessened his
awareness to the presence of the code 1200 VFR targets around the periphery of the area
or areas containing the higher priority targets to which provide separation protection.
Consequently, he might not perceive a developing threat, posed by a code 1200 VFR target
to one of his priority targets until they are in close proximity, or he might not,
particularly if his assessment of the information presented on his display is affected by
other factors such as the presence of a positive control type airspace, perceive the
developing threat at
alI
and thus not
%eett
the target.
The Safety Board concludes this
prioritizing procedure may have been, particularly when a code 1200 VFR target without
accompanying altitude information was located within the lateral confines of the Los
Angeles TCA, a reason why the controller did not perceive or see the Piper’s radar target.
With regard to the TCA, the Safety Board is also concerned that the depiction
of numerous VFR non-mode C-equipped aircraft within the horizontal confines of the TCA
may, unintentinally, encourage controllers to form certain expectations. It is obvious that
ali
of these airplanes cannot be within the verticaland horizontal confines of the TCA.
Further, since VPR traffic must, by FAA regulations, avoid entering the TCA without an
ATC clearance, a strong presumption exists that- the VFR traffic displayed within the
horizontal confines of the TCA is not within its vertical confines and therefore no threat
to aircraft legitimately within the TCA. Therefore, notwithstanding the AR-l
controller’s
assertion that he would issue traffic advisories for all such targets even though he had not
cleared them into the TCA, the Safety Board believes that the controller may have
unconsciously decided that the airplane represented by the Piper’s radar target was not
within the vertical confines of the TCA and
therefere,
was no threat to flight 498. The
controller might then have decided without conscious realization that he
------------------
z/
Easterbrook, J.A. Effects of emotion on cue utilization and organization of behavior.
Psychological Review, 1959.
48-
The decreased prominence of the
Piper’s
target on the controller% display as a
consequence of the standard configuration of the equipment in the Los
&geles
TRACON
may have been a factor in the controller’s failure to observe the target. The decreased
target prominence was a consequence of the facility decision to inhibit display of the
analog beacon return for VFR targets whose transponders were set on code 1200.
This
decision was reportedly implemented to reduce the clutter on the display which would
result from the large number of VFR aircraft in the Los Angeles basin. The Safety
Board
acknowledges that the positive and negative aspects of displaying code 1200 beacon
slashes must be considered by the controllers and facility managers in the establishment
of procedures and equipment set up.
Given the evidence concerning the radar and ARTS
III
presentation and the
controller%
actions, the Safety Board concludes that the positions of the Piper airplane
were depicted on the AR-l controller’s display by, at the least, an alphanumeric triangle,
but that ‘the controller did not observe the Piper’s radar target.
‘Ihe
Safety
Board
has
cited the following three factors that could have caused the controller to overlook the
Piper’s radar return: the possible distraction of his attention from the critical area of his
radar display caused by the projected entry of
N1566R
into the TCA and the change of
landing runways for flight 498; the possibility that the controller may have unintentionally
discounted the non-mode C VFR radar return of the Piper as a threat because it was
located within the lateral confines of the TCA; and the possibility that the primary radar
return of the Piper either did not appear on ‘his display or the strength of the return was
compromised by atmospheric interference.
The evidence does not permit the Safety
Board to select which factor or combination of factors caused this to occur. Therefore,
the Safety
Board
concludes that the failure of the controller to observe the Piper’s radar
target could have been caused by any one of the three cited factors, or by a combination
of any two these factors, or by all of them. As a result, the controller did not provide a
timely traffic advisory alerting flight 498 to the presence of and relative position of the
Piper PA-2 8.
The failure of the controller observe the radar return of the Piper and, thus, to
provide a timely traffic advisory to flight 498 placed that
flightcrew
in the same position
as all other VFR pilots flying in visual meteorological conditions
(VMC);
their ability to
see and avoid other airplanes depended on their alertness, the quality of their scanning
procedures, and the conspicuity of the targets they were seeking to acquire.
‘Ihe
Safety Board cannot state with certainty that this collision would have
been prevented by a timely traffic advisory;
midair collisions have occurred after pilots
have received relevant ATC traffic advisories.
l.J
However, a traffic advisory would
have alerted the Aeromexico pilots of a specific threat and provided a relative bearing
from their airplane along which they could concentrate their attempts to see the
threatening airplane.
The Safety Board believes that had this advisory been provided, it
would have increased the Aeromexico
flightorew’s
chances of seeing the Piper in time to
avoid the collision.
Although the Federal Aviation Regulations
13/
required the
Aeromexico
flight&w
to maintain
continous
vigilance to see and
avoid%her
aircraft, a
timely traffic advisory would have increased their ability to exercise this responsibility
efficiently. Therefore, since the failure to provide this warning decreased the
Aeromexico flightcrew’s chances to locate the Piper, the Safety Hoard concludes that this
failure was a contributory factor in the accident sequence.
lJ
Pacific Southwest Airlines
Boeing
727 and a Cessna 172, San Diego, California,
Septe mber 2
5, 197 8
(NTSB-AAR-79-5).
13/
14 CFR Part
91.67(a)
states in part, When weather conditions permit, regardless of
s
aether
an operation is conducted under Instrument Flight Rules or
Visual
Flight’
Rules,
vigilance shall be maintained by each person operating an aircraft so as to see and avoid
other aircraft in compliance with this
section.tt
-49-
on the cockpit visibility study (appendix G), both airplanes were within
the pilot’s
of vision for at least 1 minute 13 seconds before the collision-but with
certain limitations.
The visibility study showed that the Piper was visible through the
center windshield of the DC-9 as viewed from the first
officer%
seat, and about half the
lots
showed that the Piper was located in the first officer’s monocular vision field. In
on, since the captain was making all air to ground radio communications, the Safety
concludes
that the first officer was flying the airplane.
Over
half of the position
plots for the Piper airplane show that it was visible to the captain through windshield and
was within his normal binocular vision field.
‘Ihe
Safety
Board
determined that the person occupying the right seat in the
ilot
and had never received scan training. Therefore, for this analysis,
assumed that only the pilot was or could have scanned for other
olely
on the relative size of the two airplanes, the Probability of Visual
Acquisition Graphs (appendix
H)
show that the Piper pilot had a better chance of seeing
the DC-9 than the Aeromexico flightcrew had of seeing the Piper. However, the location
ieted
on the Piper visibility study, showed that the DC-9 was visible
een and near the outer limits of a left-right scanning
cannot assume that any of the passengers would have
an for airplanes, the location of the
DC-g,
despite its greater
reduced the Piper pilot’s ability to see it. Further, given the available
fety
Board
cannot reach any conclusion concerning his alertness to the
d
maintenance of an active scan for other airplanes.
~romexico
regulations do not contain specific procedures limiting cockpit
~~~ve~sation
and prohibiting flight attendants from entering the cockpit during critical
those for U.S. air carriers.
However, its regulations do require the
closed during flight and they state specifically who may occupy the
‘Ihe
available evidence does not permit any conclusions that the
ion to required duties was compromised during the descent.
d solely on the location of the Piper on their airplane’s windows and
Aeromexico flightcrew should have had an almost unobstructed view of
Although the first officer was flying the airplane, the autopilot, in
mpany policy and procedures, should have been engaged, thus freeing
f the duties associated with hand-flying the
DC-%
Of greater
e
fact that the Piper was approaching the DC-9 from the non-flying
ss than a
30’offset
to the left; thus, the Piper was in an area where the
natural
scan and attention should have been focused. Mitigating against these
maller size of the Piper and the fact that it was, visible to the first
the center windshield. In addition, because the airplanes were on a
relative motion of the Piper would presumably been minumal and,
thc~efo~e,
it would have been more difficult to detect.
ddition to the limitations imposed by cockpit structure, the physiological
of the human eye to identify targets also limited the ability of the pilots to see
e. Data indicates that, as a minimum, targets should subtend a visual
minutes) of arc to reasonably ensure accurate recognition.
E/
The Piper
nded a visual angle of
0.2’of
arc when it was a little over 1 nmi away or
eolllision.
‘Ihe
DC-S
would
have subtended this
visual angle when it
or
about 1 minute 23 seconds before the collision.
nd Kinkade, R
“Human
Engineering Guide to Equipment Design,”
ican
Institute for
Research, Washington, D.C., 1972.
-5o-
The visual acquisition charts further illustrate some of the difficulties pilots
face in seeing and avoiding other targets.
‘lb
be effective, the pilot must see the other
aircraft in time to initiate and complete an evasive maneuver. FAA Advisory Circular
(AC)
90-48C,
which is based on militaryderived sources, states that the total time
necessary for a pilot to see an object, to recognize it as a potential midair target, and
then to execute an evasive maneuver is 12.5 seconds.
‘Ibe
TCAS resolution maneuver is
supplied to the pilot between 25 to 30 seconds before the airplane reaches the projected
collision point.
Given these data, the Safety
Board
believes that, for this discussion,
15
seconds would be a reasonable time for a pilot to recognize a potential target and execute
an evasive maneuver.
The visual acquisition chart indicated that the Piper pilot had an 80 percent
probability of seeing the DC-9 at 15 seconds before the collison.
With both pilots of the
DG9
looking, the probability of their sighting the Piper airplane 15 seconds before the
collison was 30 percent and with one pilot looking, the probability diminished to
15
percent. With regard to
“see
and
avoid,”
the evidence indicated that the pilot of the Piper
had a high probability of sighting and avoiding the
DC-g,
whereas the probability of the
Aeromexico flightcrew sighting and avoiding
could’only
be characterized as marginal, at
best. However, while these data indicate that
%ee
and
avoid”
is not a totally acceptable
concept, other evidence indicates that its viability cannot be dismissed summarily.
During 1985 and 1988, pilots reported a total of 1,598 near midair collisions
(NMAC)
to the FAA.
E/
During this
2year
period, 341 NMACs were classified critical,
887
potential, and the remainder were either adjudged no hazard, “unclassified,” or
%pen.”
The 887 potential NMACs indicate that pilots do see and do avoid other airplanes
while flying in visual flight conditions.
Regardless of the above considerations, both airplanes were operating in visual
flight conditions and therefore were required by regulations to see and avoid each other;
however, in this case, their failure to do so must be evaluated in context with the
limitations placed on the pilots by the angles of closure, the size of the targets, the
conspicuity of the targets, and the physiological capabilities of the human eye to
accomplish this task.
The charts showing probability of visual acquisition also demonstrate the value
of alerting pilots to the presence and location of a collision threat.
‘Ihe
chart indicates
that had a TCAS alert been provided to the DC-9 pilots, the probability of acquisition
with both pilots looking would have increased from 30 percent to 95 percent. However,
the 95 percent probablilty of acquisition was based on a TCAS alert that provided the
target’s relative hearing, range, and altitude. In this instance, the Aeromexico flightcrew
would have been provided only the Piper’s relative range and bearing. While the absence
of altitude information would have made the pilot’s task of visually acquiring the target
more difficult, the probability of acquisition still would have exceeded that of an
unalerted flightcrew.
In conclusion, the Safety Hoard has recommended the development of TCAS
and the establishment of
TCAs
as a means to lessen‘the risk and possibly to eliminate the
occurrence of midair collisions near major air traffic hubs. The evidence shows that,
first, had flight 498 been equipped with a TCAS, the accident might not have occurred and
second, had the Piper been. mode C-equipped, the collision probably would have not
occurred. The Safety Hoard believes that the ‘TCAS development program must be
expedited and the installation of TCAS must be mandatory on all air carrier and
-a-
15/
Selected Statistics Concerning Pilot Reported Near Mid-Air Collisions; U.S.
spartment
of Transportation; FAA; Office of Aviation Safety; Safety Analysis Devision.
--
-52-
il
3.2
CONCLUSIONS
E!?m!tE
1.
2.
3.
4.
5.
6.
7.
The airplanes collided at a
90°angle,
at an altitude of about 6,560 feet,
and in visual meteorological conditions.
The
collision occurred inside the
Los Angeles TCA.
Roth pilots were required to see and avoid the other airplane.
There
was
no evidence that either pilot tried to evade the collision.
The pilot of the Piper was not cleared to enter the Los Angeles
TCA.
His entry was inadvertent and was not the result of any physiological
disablement.
The unauthorized presence of the Piper in the TCA was a causal factor
to the accident.
The positions of the Piper were displayed on the AR-l controller’s
display by, at the least, an alphanumeric triangle; however, the Piper’s
primary target may not have been displayed or may have been displayed
weakly due to the effects of an atmospheric temperature inversion on
the performance of the radar.
‘Ihe
analog beacon response from the
Piper’s tranponder was not displayed
because of the equipment
configuration at the Los Angeles TRACON.
The AR-l controller stated that he did not see the Piper’s radar return
on his display, and, therefore, did not issue a traffic advisory to flight
498.
His failure to see this return and to issue a traffic advisory to
flight 498 contributed to the occurrence of the accident.
The Los Angeles TRACON was not equipped with an automated conflict
alert system which could detect and alert the controller of the conflict
between the Piper PA-28 and flight 498.
Rotmble
cause
The
National Transportation Safety
Board
determines that the probable cause
of the accident was the limitations of the air traffic control system to provide collision
protection, through both air traffic control procedures and automated redundancy.
Factors contributing to the accident were
(1)
the inadvertent and unauthorized entry of
the PA-28 into the Los Angeles Terminal Control Area and (2) the limitations of the
%ee
and avoid” concept to ensure traffic separation under the conditions of the conflict.
4.
RRCOYMBNDATiON
91
Recommendations
Addresdi
Midnir
Cellbion
5
Since 1967, the Safety
Board
has
issued-*116
recommendations as a result of its
investigations,
special studies, and special investigations of midair or near midair
collisions. A review of these 116 recommendations identified 56 that are pertinent to the
accident at Cerritos (appendix
HI.
-53-
The 56 recommendations suggested changes and/or improvements that the
Safety Board believed would decrease the midair collision risk. The areas addressed in
these recommendations included among others:
radio communication procedures;
development
of ATC procedures to provide separation between high-and-low performance
aircraft in high-density terminal areas; improvement of ATC radar capability;
improvement of aircraft conspicuity, particularly the development and installation of
anti-coIlision
light systems and the requirement to use these lights day and night; and the
development of airborne collision warning systems.
On November 4, 1969, the Safety
Board
convened a public hearing to
ate the subject of mid-air collisions.
As a result of the hearing, 14 safety
recommendations were sent to the FAA. Recommendations A-70-5 through -15 were sent
to the FAA on
y 22, 1971.
These
14 recommendations addressed the area cited in
the
previous
ng
this
1%
year period, the remainder of the recommendations sent to the
inued to stress these areas of concern and, where warranted by facts
during other investigations, to amplify and reiterate matter and materials
contained in some of the earlier recommendations.
The history of these 56
ommendations and the actions taken by the FAA in response to them is contained in
a result of this accident investigation and a review of the
FAA’s
ongoing
Safety
Roard
reiterates the following recommendations to the FAA:
Expedite the develop ment , operational evaluation, and final
certification of the Traffic Alert and Collision Avoidance System
)
for installation and use in certificated air carrier aircraft.
11,
Priority Action) (A-65-64)
end
14 CFR Parts 121 and 135 to require the installation and
of
Traffic
Alert and Collision Avoidance System
(TCAS)
equi@me~t
in certificated air carrier aircraft when it becomes
av
le
for operational use. (Class III, Longer Term Action) (A-
85
ition,
the Safety rd recommends that the FAA:
plement procedures to track, identify, and take appropriate
ment action against pilots w
intrude into Airport Radar
Areas
(ARSAs)
without the quired Air Traffic Control
mmunications. (Class
11,
Pri
ty Act ion) (A-87-96)
e transponder equipment with mode C altitude reporting for
‘ons
around all Terminal Control Areas
(TCAS)
and within an
dar Service Area
(ARSA)
after a specified date
th
implementation of Traffic Alert and Collision
tern
(TcAS)
requirements for air carrier aircraft.
nger Term Action) (A-87-97)
dited action to add visual flight rules conflict alert
intruder) logic to Automated Radar Terminal System
A systems as an interim measure to the ultimate
tation
of the Advanced Automation System
(AAS).
Longer Term Action) (A-87-98)
-54-
BY
TER
NATIONAL TRANSPORTATION SAFETY BOARD
/S/
IS/
IS/
/S/
IS/
JIM BURNETT
Chairman
PATRICIA A. GOLDMAN
Vice Chairman
JOHN K. LAUBER
Member
JOSEPH T. NALL
Member
JAMES L. KOLSTAD
Member
Jim Burnett, Chairman, filed the following dissenting statement regarding
probable cause and contributing factors:
The
National Transportation Safety Board determines that the probable cause
of the accident was the limitations of the air traffic control system to provide collision
protection, through both air traffic control procedures and automated redundancy.
Contributing to the accident was the inadvertent and unauthorized entry by the pilot of
the PA-28 into the Los Angeles terminal control area and his failure to see and avoid the
DC-9 prior to the collision.
/s/
JIM BURNETT
Chair man
July 7, 1987
-55-
5. APPENDIXES
APPENDIXA
INVESTIGAT¶ONANDKRARlNG
L
The
Safety
Board
was notified of the accident at 1520 eastern daylight time on
1986,
Investigators from the Safety
Board’s
Los Angeles, California, Field
e on the accident scene within 30 minutes of the accident and cooperated with
w enforcement agencies in securing the accident scene. A team of investigators
was dispatched from Washington, D.C., and arrived on the scene at 2200 Pacific daylight
time on August 31. Investigative groups were formed for operations, air traffic control,
witnesses, meteorology, survival factors, structures, powerplants, systems, maintenance
ords, flight data recorder, cockpit voice recorder, airplane performance, and human
formance.
The parties to the investigation were the Federal Aviation Administration,
Ae~omcx~co
Air Lines, the International Federation of Air Line Pilots Association, Piper
nnell Douglas, the Aircraft Owners and Pilots Association, and the Flight
Attendants Association of Mexico.
A
~presentative
of the Director General of Civil Aviation of Mexico was
the
accredited representative of the government of the Republic of Mexico
ted in the investigation.
A
4-&y
public hearing was held in Los Angeles, California, beginning
Parties represented at the hearing were the Federal Aviation
omexico
Air Lines, the International Federation of Air Line Pilots
ciation,
Piper
Aircraft, the Aircraft Owners and Pilots Association, the Plight
ociation of Mexico, and the Professional Airways Systems Specialists.
esentative of the Director General of Civil Aviation of Mexico was
ointed as the
accredited representative of the government of the Republic of Mexico
rticipated
in the public hearing.
APPENDIX B
-57-
Air.
Traffic Control ‘Personnel
Mr. Walter
IG
C.
White
Mr. Walter R. C. White, 35, was employed by the FAA on December 1, 1980. His
ent
medical examination was performed December 3, 1985.
The controller received his initial training at the FAA Academy, Oklahoma City,
had worked at Brown Tower and Montgomery Tower in San Diego,
at Coast Tracon, El Toro Marine Corps Air Station, California, where he
d Full Performance Level
(FPL)
Controller status. In December 1984,
Mr.White
red to the Los Angeles TRACON. At the time of the accident, Mr. White had not
achieved the
FPL
rating at the TRACON because he had not been certified on the
TRACONfs
arrival and departure coordinator positions.
-58-
APPJZNDIX
C
FDR DATA,
ARROMRXICO
NATIONAL
7RANSPORTATlON
SAFETY
BOARD
BUREAU OF TECHNOLOGY
WASHINGTON,
Lt.
C.
-59-
APPENI)l.X
D
CVB TRANSCRIPT, AEROMEXICO
TRANSCRIPT OF A SUNDSTRAND MODEL
v557
COCKPIT VOICE RECORDER
S/N
1829,
REMOVED FROM THE AEROMEXICO DC-9 WHICH WAS INVOLVED IN A
MIDAIR COLLISION WITH
A PIPER
PA%181,
N9891F,
AND AIR TRAFFIC
CONTROL (ATC) RECORDING
FROM LOS ANGELES TRACON AND
COAST APPROACH
CONTROL, NEAR CERRITOS,
CALIFORNIA, ON AUGUST 31, 1986
C
RDO
-1
-2
-1
UNK
LA APP
222
5225
3
N1566R
CR
Cockpit area microphone voice or sound source
Radio transmission
from
accident aircraft
Voice identified as Captain
Voiee identified as First Officer
Voice unidentified
Unknown
Los Angeles TRACON Control (Approach Control)
Coast Approach Control
Sky West Flight Two Two Two
Wings
.West
Flight Five Two Two Five
Wings West Flight Five Oh Eighty Three
Grumman November One Five Six Six Romeo
Aeromexico Company at Los Angeles International Airport
Unintelligible word
Nonpertinent word
reak in continuity
Questionable text
Editorial insertion
use
All times are expressed in Pacific daylight time.
INTRA-COCKPIT
CONTENT
11:42:35
CAN-7
c*
AIR-GROUNU
CUMMUNICAIIONS
TItU
a
SOURCE
CONTENT
ll:41:21
RDD-I
Coart
Approach
goud
morning,
thio
is
Aeromexico four ninety
eight
is level
one zero
chowand
ll:41:27
CtMST
Aeromexico four ninety eight,
Coast
Approach
good morning,
rogcr
one zero
thouaaad
proceed
direct
Seal
gexch
El
Toro
xltiretcr
tuo
niner
ainer
air
11:41:35
gDD-1
Direct
Sex1
gexch
altimeter
two. niner
ninet
six
11:43:36
COAST
1
I
:43
:44
RDWI
11:44:54
ltDw1
-I
I
:44:58
CWST
Arraexico four ninety eight,
cruaw
one
zero
rile@
southeart
of
geal
Beach at and
mxintain
reven
thoueaad
’
One
zero
miles seven thousand Aeromexico
four ninety eight
Aeromexico four ninety eight
iar
leaving
one
zero
thousand
for seven
thourand
Aeruwxico
four
ninety eight
ruger
AIR-CROUNU
CW4UNICAlIONS
TM
8
SOURCE
CONTENT
e
rrsmvaye
twenty
four
right
left
111:46:46
CAM
((Sound
of LAX
ATIS
xtcrto))
11:46:59
ca!rr
Aeraexico
four
ninety eight contact
Loa
Angeleo Approach one two four point
niner
11:47:03
IUD-1
One two four point niner, good
day
((ATIS
endo))
‘B
I
11:47:05
COAST
Good day
11:47:23
CA+2
11:47:24
CAN-1
-
depart
urcc
(kre
aeven
and twenty four
I
I
:47:2g
IUUH
Los
Angelax
Approach good morning,
this
ia
Aeromexico four sixty four four ninety
eight
uh
we’re leaving,
ve’re
level one,
correct ion
aeven
thouaxnd
*
z
Q
s
u
IN-HA-COCKP
I
8
A I H-CROUNU
CUMJNI
CAT I Oh>
;gc:
CONTENT
11:47:34
CM-2
+
TIME 6
SOURCE
CONTCNT
-
4
-
11
:I7
:37
CAM-1
Ye8
mu8
11:47:3Y
LA APP
Aerouexico four ninety eight Los Angeles
Approach depart Seal Beach three two zero
vector ILS
two
five left final
approwh,
do you have Information Uniform
1
I
:47:46
RD+I
Affirmative two five left runway
I1
:47:49
CAN
((&und
aimular altitude alert tone))
11:47:50
cAn-2
Tuo
tuo
zero
for the runway
-
11:47:53
LA APP
Sky
West
tuo
twenty tvo, traffic twelve
o’clock four
milea
northbound, altitude
unknom
11:47:57
SKU222
Looking triple two
11:47:59
LA APP
Wings
Uert
fifty two twenty five reduce
speed to one seven zero
,
-
3
-
CONTENT
11:48:15
CAM-1
Flight director up
11:4$:16
CAM-2
Flight director up
11:48:31
CA&?
l
.
AIR-CHOUNU
COtMUNI
CAT
1Utc
TIME
Q
SOURCE
CONTENT
If
:48:03
MM5225
Fifty two tventy five reducing to one
seventy,
vtt
have the airport in sight
II
:48:06
LA APP
Thank
you
11:48:09
CAM
((Sound of attendant call tone))
11:48:14
CAn-2
Course two four nine
-
8
I
1 I
:48:22
SKW222
And uh Approach
was
that fifteen hundred
feet until advised landing’for Sky West
triple tvo
I I
:411:27
LA APP
Sky West tvo twenty tvo correct
1
I
:48:29
SKW222
Thank
you
TIM
6
SOURCE
CONTENT
11:48:52
LA APP
11:48:57
W5225
11:49:00
LA APP
I I
:49:08
SKY222
11:49:10
LA APP
11:49:11
SKw222
II
:49:18
LA APP
11:49:2?
bnms225
AM-TrHOUNU
COmUNICAClUNS
TIME
6
SOURCE
CONTLN
I
Ming6
West fifty tvo tventy five
deticrnd
and maintain four thousand
Four thousand Wings fifty tvo tventy five
Sky
Uert
tvo tventy tvo traffic ten
o’clock two miles northveatbound is a
Merlin
et
air thousand descending, he’s
fur tvo five left
We’re looking for him triple
two
Say that again air
Ue’re
looking for him, he’s not in sight
yet
,
Wings Yest fifty tvo
tveoty
five, the
)krlin
you’re folloving is tvo o’clock aud a mile
and a
ha1
f vest bound
at
three thousand,
expect a turn to f
inol
in a l i le
Fifty tvo tventy five looking for him,
ve
dill
heve
the airport in sight
h
11:49:41
CAN
((Sound of tone))
-I-
~NTRA-COC~~
B
AIR-GROUND
COWUNICAT
ION’;
TIME
h
SOURCE
CONTENT
11:49:3P
LA APP
11:49:36
gDC-1
.
11:49:36
tfW5225
11:49:37
LA
APP
11:49:40
CCNPANY
I1
:49:41
LA AYP
11
:49:42
RIH)-1
1
I
:49:44
CWlPANY
Yea sir,
I
‘I
gonna need you to see
him,
he’s gonna pull out from under your nose
in another aile or so
Aeraexico *
Roger
Wings fifty
tva
tventy five, turn left
heading tvo five zero
(Aeromexico
four nine eight go ahead)
Pifty tvo tventy five turn left heading
tvo five zero
lhank
you *
t
I
* l
Aerumaxico
four ninety eight estimate
fifteen minutes, you have assigned gate
one hundred and nineteen and nineteen
one one nine avaiting your arrival
APPENDIX
D
-
Y
-
lNT~-CQC~T
T
AIR-GROUND
CUMlUNICAI’iON~
TIME
C
SOURCE
CONTENT
TIME
6
SOURCE
CONTENT
11:SO:lO
LA APP
11:50:18
MS225
.
11:50:22
IA
APP
11:50:23
ww5225
11:50:24
LA APP
11:50:‘10
UUNS225
11:50:39
U
APP
Wings fifty tvo tventy five, the traffic
is
nov,
correct
ion,
turn left heading tvo
three xero, the traff ic’a at eleven o’clock
and a mile
ILo
three zero fifty tvo tventy five
roger
and uh
Understand you have him in sight
Yes
sir,
ve got him in a ight
Winye
West fifty tvo twenty five,
follov
that aircraft, he’s for tvo five right,
you’re cleared for a visual approach to
runvay tvo five left, contact Los Angeles
Tover one tvo zero point
niher
five, good
day
5
I
Cood day
Wings
West
fifty eighty three, traffic
twelve o’clock, four miles northbound,
a
It
it ude
unkoom
INTRA-COCKPI’
’
11:50:43
ulBlSO83
11:51:20
II
:50:46
LA APP
*
11:50:50
RDO-I
11:51:03
LA APP
11:51:09
RDWl
11:51:18
Ml
5661
AIR-CROUNU
COM~UN~CAC~~IJ~
TIM
6
SOURCE
CONTEN
r
l fifty eighty three
Aeromexico four ninety eight, traffic ten
o’clock one mile northbound, altitude
unknown
Roger four ninety eight
Aeromexico four ninety eight reduce
speed to one niner
zero
then descend and
maint sin a ix t houaand
One niner
zero
and then descend and
maint sin sin thouaxod
LA Center uh
Cr-an
gne
fhe six six
romeo
CAM-2
t
11:51:23
LA APP
crumman
one
five air l ix
rumeo.
this is
Loo Angeles Approach
,
L
‘
INTRA-COCKPIT
TIME
11
SOURCE
CORTENT
11:51:30
CM-1
Thank you
-
II
-
AIR-GROUND
COblMUNICATIONS
TIMC
b
SOURCE
CONTENT
11:51:26
WI
5661
~RI
LA Approach eix six
romeo
io
on a
VFR flight out of
Ir,llerton
uh vith a
first atop uh into Van
kayo
VOR
deat
inat
ion gonna be uh Monterey, alt it ude
vi11
be four thousand five hundred, ve’d
like folloving
11:51:44
LA APP
11:51:48
WO-1
11:51:57
IA
APP
11:52:00
RIM-1
11:52:04
U
APP
Aerwexico four ninety eight,
Baintain
your present speed
tbger
Aeromexico four ninety eight uh
what
speed do you vant , ve
’
re reducing
to tvo niner to one niner
zeru
Okay, you can hold
vhict
you have sir, and
ve have a change in plans here, stand by
All right
vu’11
maintain one nine
-.-
nine aero
Cruao
six six romeo aquavk four five
two
four remain clear
of
the uh
TCA
I
$
%
3
3
j;i
u
INTRA-COCKPIT
TIM
6
SOURCE
CONTENT
-
12
-
plR-GROUNO
COMMUNICAIIONS
TIME
6
”
SOURCE
CONTENT
11:52:09
WI
566R
yuur
five, vbat vere the other
tvo
numbers
11:52:10
an-1
Ob
@
this
can’t be
11:52:11
LA APP
Four five tvo four
11:52:15
Ml
566R
Four five tvo
four
11:52:18
LA APP
Aeromexico four ninety eight, expect the
ILS runvay
tvo
four
right approach
localizer
frequency is one zero eight
point
fivk
11:52:32
((Knd
of
Tape))
-?l-
APPENDIX
B
COCEPIT
VISIBILlTY
STUD=
The
visibility
diagrams for the DC-930,
XA-JED,
are on pages 72 and
72;
those for
the
Pi@er
PA-28-181,
N4991P,
are on pages 74 and 75.
.
,
m
.
I
.
.
I
.
IrI1l.I
-10
0
10
40 60
a0
loo
azxlamn
lDs8.l
-75-
;,;,!
APPENDIX
E
-IS-
APPENDIX
F
ATC
TRANSCRIPT
’
Memorandum
s,,t,ject.
IEQR-lATION:
Transcription concerning the
Daw
Septmber
9, 1986
accident
involvinq
Aeranexico
Flight 498
and’
N4891F
on
August
31,
1986 at approximately 1852
UX
RtDly
to
F~CF
Plans and Procedures Specialist,
bs
AngelesiTRACON
AI!*
e*
70.
This transcription
covers
the time period
fran
August 31, 1986, 1837
UK
to August 31, 1986,
19Cl
UK.
Agencies Making
Transmissions
Abbreviation
Los
Angeles
Terminal Radar Approach
Control Arrival
EBdar
1
AR-1
I-#
7
Los Angeles
ARTCC
Sector 20
2LR
20
Pacific Southwest Airlines Flight 1765
PS1765
Wings West Airlines Flight 5225
Sky West Airlines Flight 222
Wings West Airlines Flight 5083
MM5225
SW222
MS083
Aeranexico Flight 498
Grmman
AA'5,
N1566R
m
American
Airlines
Flight 333
AM498
w
N1566R
AA333
I
hereby certify that the
following
is
a
true transcription
of
the recorded
conversations pertaining to the subject aircraft accident:
~Lh---
v
Sham L. Moore
.
-
Idx-TRAcaJ-068
Page 2 of 12
(1837)
(1838)
(1839)
(1840)
(1841)
(I8421
1842: 14
1842: 16
1842:
25
l.842:
55
PS1765
AR-1
PS1765
V&W5225
AR-1
WW5225
-77-
APPENDIX
F
where’s the little guy now
p s a seventeen sixty five twelve
‘clock’o;ma;:~~
southbound altitude
u&nom
aS$i
t
ional
twelve o’clock and four
miles
sbutheastbound
nine
thousand three hundred
1oDking
10s
angeles
approach
wings,est
fifty two twenty
five seven thousand uniform
calling 1 a
roach
say again
wings west fifty two twenty five seven thousand
uniform
APPENDIX
F
-78-
uu(-TPACON-068
Page 3 of 12
1843: 12
1843: 19
M5225
1843: 22
AR-l
1843:27
(1844)
(1845)
18
45:10
1845: 14
.
.
1845: 28
1845: 30
1845: 4C
1845:
4’7
wings fifty two
tenty
five
10s
angeles approach
depart seal beach heading three two
IWO
expect
a visual approach
rummy
two five left report
airport in sight thanks for
unifom
fifty two twenty five we’ll do it
p s a seventeen sixty five v f
r
traffic is no
longer a factor you have
a
nice weekend
PS1765
thank you sir bye bye
A?.-:
AR-1
z&A
20
AR-1
SICK222
AR-1
sky west
tiz
twenty
tw=,
twenty downe ship sky
mst
two twenty two again
please
here he canes
thanks
10s
angeles approach sky west triple two with
you we’re descending out of
niner
thousand with
the restrictions
Ot
fuelr we have the airport
uniform
c
sky west two
twenty
two
10s
angeles approach after
fue:r
cleared
fer
visual approach runway two five
right you’re number one maintain two hundred forty
knots or faster until downe traffic inbound over
seal
beach
is another merlin
.will
have you in
sight and follow he’s gonna be for two five left
APPENDIX
P
-80.
Page 4 of 12
1847: 28
1847: 40
1847: 46
1847: 53
1847: 57
1847: 59
(1848)
1848: 03
1848: 06
1848: 22
1848: 27
.
. .
1846: 29
AM498
AR-1
AM498
AR-1
SW222
AR-1
WW!‘l5225
AR-1
SW222
AR-1
SK222
10s
angeles approach good morning this is aeranexico
four sixty
foti
four ninety eight uh we’re leaving
we’re level one correction seven
thousad
.
aeranexico four ninety eight
10s
angeles approach
depart seal beach three two zero vector i 1 s
two. five left final approach course do you have
information
dfoxn
affirmative two
five
left
runmy
sky west two twenty two traffic twelve o’clock
four miles
northboti
altitude unknown
looking triple two
wings west fifty two twenty five reduce speed
to one seven zero
. .
fifty two twenty five reducing to one seventy
we have the airport in sight
thank you
and
uh
approach
was
that
fift-n
hundred feet
until
advissd'landir@
for
sky west triple two
sky
wpst
two twenty two
correct
thank you
..
l
-81-.
APPENDIX
F
LAX-TRKON-06
8
Page 6 of
1,
1848: 52
1848: 57
1849:
C3
1849: 08
1849:10
1849:
11
1849: 18
1849: 27
1849: 31
AR-1
ViWM5225
AR-1
sm
222
AR-1
SW222
hVY522
f
AR-1
MS225
wings west fifty two twenty
five
descend and maintain
four
thousand
four thousand wings fifty two twenty five
sky west
two
twenty two traffic ten o’clock
tw;
miles northwestbound is a merlin at six thousand
descending he’s for
two
five left
we’re looking for him triple two
say #at again sir
we’re looking for him he’s not in sight yet
wings west fifty
two
twenty five the merlin
following is
two o’clock and a mile and
westbound at three thousand
expect
a turn to
in a mile
you’re
a half
final
fifty
twc
twenty
five looking fcr
hire
we
still
have the airport in sight
yes sir
i’m
g‘onna
need you to see him he’s
gonna
pull out fran under your nose in another mile
or
so
roger
wings fifty
two
twenty five turn left heading
two five zero
fifty
s
two twenty
five turn
left
heading two five
zero
APPENDIX
F
-82-
KAX-TR?cm-068
Page 7 of 12
1849: 44
1849: 46
1849:
54
WHY5225
1849: 57
AR-1
(1850)
1850:
01
sm222
1550:
05
1850:
Be
1850: 10
1858:18
1850: 22
lE5C:
23
hIbX5225
AR-1
AR-1
As1490
AR-1
WW35225
AR-1
NW5225
left two five
zero
fifty two twenty five
wings west fifty
two
Wty
five
bo
you
6ee
the
traffic now at
your
mlve
o’clock
an3
a half
mile westbound two thousand descend
and
maintain
three thousand
down to three
thousati
wings fifty two twenty
five
no
we
don’t
got
him
sky west two twenty two contact
10s
angeles
tower
one two zero
pint
nfner
five at
limna
good day
aeranexico four ninety eight
‘reduce
speed to two
one zero
tw3
one zero four ninety eight
wings fifty two twenty five the traffic is now
correction turn left heading two three zero the
traffic’s at eleven
o’clock
and a mile
two
three
zero fifty two
twmty
five
roger
and
uh
understand you have
I!&
in bight
yes sir we got him in sight
;
CAX-TRACQN-068
@age
8 of
1050: 24
12
AR-1
1850: 30
It%+!5225
18§0: 39
AR-1
1850:
43
WJM5083
1856:
46
AR-1
1850: 50
AM498
(1851)
1851:W
AR-1
498
Nl566R
AR-1
:26
N1566R
-83-
APPENDIX
F
wings west
fifty
two twenty’ five follow that aircraft
he’s for two five right
you’re
cleared for a visual
approach to runway two five left contact los angeles
tower one two zero pint niner five good day
good day
wings west fifty eighty three traffic twelve o’clock
four miles
northbourx3
altitude unknown
(unintelligible) fifty eighty three
seranexico
four ninety eight traffic ten o’clock
one mile northbound altitude
unknown
roger
four ninety eight
aeranexico four ninety eight reduce speed to one
niner zero
th?n
descens
ati
maintain six
thousati
one niner zero and then descend
and
maintain six
thousand
1 a center
uh
grunmn
one five six six
raneo
grimman
one five six six raneo this
is,los
angeles
approach
uh 1 a approach six six
ramo
is on
a
v f
r
flight
out
of fullerton
uh
with a first stop
uh
intc
van
ntys
v o
1:
destination
gonna
be uh monterey
altitude will
be
four thousand five hundred we’d
like following
APPENDIX
F
-84-
LRX-TRACON-068
Page 9 of 12
1851: 45
1851t48
1851:57
1852: 00
AM498
1852: 04
AR-1
1852: 09
1852:ll
1852: 15
1852: 18
1852: 29
1852: 32
1852: 36
AR-1
AM498
AR-1
N1566R
AR-1
N1566R
AR-1
AR-1
N1566R
AR-1
aeranexico four
ninety
eight maintain your present
.
roger aeranexico four ninety eight uh what speed
do you want we’re reducing to
two
niner to one
niner zero
ok you can hold what you have sir and we have
a change in plans
.sir
rtand
by
alright
~‘11
maintain one niner zero
grunnan
six six
r-0
squawk four five two four
remain
clear of the uh t c a
four five what were the other two
nunbers
four five two four
‘.
.
four five two four
aeranexico four ninety eight expect the i 1 s
fmway
two
four right approach
localizer
frequency
IS
one zero eight point five
grumnan
six six
raneo
are you at four thousand
five hundred now
uh negative we’re at three thousand four hundred
climbing
ok you’re right in the middle of the t c a sir
grumnan5ix
six raneo
i
would suggest in the future
you look at your t c a chart you just had an aircraft
pass right off your
left
above you at five thousand
and we run a lot of jets through there right at
thirty five hundred
-8%
APPENDIX
F
-TRAccN-068
e 10 of 12
1852: 50
L
1852: 58
(1853)
1853:
03
1853: 08
1053: 15
1853: 24
1853: 31
h853:
48
~58
Rl566R
AR-1
AR-1
AR-1
AR-1
AR-l
Ah333
AR-1
AR-1
AR-1
i was with
coast approach and
they did not advise
me of this i
was with Ontario
approach and they
sent
me
over
to you what
do
you
mlggestidonow
aeramexico
four ninety eight
two eight
zero
aeranexico four ninety eight
two eight zero
aemnexico four ninety eight
two eight zero
turn left beading
turn left heading
turn left heading
grmnan
six six
raneo
standby aeranexico four
ninety eight turn
left heading two eight zero
over
;
’
‘.
aeranexico four ninety eight
10s
angeles approach
i0s
angeles
approach
amer
ican
three thirty three
heavy one
zero
thouand
for the two five profile
descent
and
uh
we have uh uniform
aeramxico
four
nihety
eight
10s
angeles approach
wings fifty eighty three tower one two
Zero
point
niher
five
aeranexico four ninety eight
10s
angeles approach
APPENDIX
P
-86-
XAX-TRAcaM68
Wge
11 of 12
(1854)
lB54:08
lB54:22
1854:
28
1854:31
lB54:57
(1855)
1855:16
1855:28
1856:0;
lB56:05
1856:17
AA333
AR-1
AR-1
AA333
AR-?
AR-1
AR-1
AA333
AR-1
AA333
10s
angeles approach.
mnerican
thzee
thirty three
heavy
uh
descetiing
but of nine point four for
the
profile descent
Md
uh
we
have
miform
akramexico
four ninety eight
10s
angeles approach
merican
thr three thirty three heavy maintain
eight thousand
merican
three thirty three maintain eight thousand
gruman
six six
rOneO
you’re leaving the
10s
angeles
t c a now radar service is terminated squawk one
two zero zero
fre&ency
change is
approved
good
&Y
,
aeranexico four ninety eight
10s
angeles
approach
american
three thirty three heavy
uh
standby
trJe
need
lower
umerican
triple three heavy
8nerican
three thirty three heavy
nsgative
uh
i want you to look around at
elwen
o’clock and
about five miles
i
just lost contact with a d
c nine let me
knqq
if you see anything down there
please
uh
e+ven
o’clock
uh
five miles what altitude
-87-
APPENDIX
F
IAX-TRACCN-068
Page 12 of 12
1856: 21
AR-1
he was last assigned six he’s no longer on my
radar scope
american
three
thirty three heavy
1856: 26
AA333
okay i see a uh very large uh
sake
screen off
on the left side of the aircraft
abeam
uh
the
uh
the nose of the airplane right off our left
it is a very large
make
uh
calm
uh caning
frm
it and uh
manating
fran the ground and at our
altitude at eight thousand feet there’s another
mnoke
colmn
vertically overhead it looks like
it
suneming
smked
up uh ahead and then went
down in
(1857)
(1858)
(1859)
(1900)
(1981)
ENil
OF TRANSCRIPT
-88-
AwBNDIxo
FAA
ltEcoMIuBNDARONIP
.
.
ACTION:
Agcnoy
Aotion
to Implement
~ajwt:
Reoomoendrtlons
Developed by the
TerminS
Control
Atie
(TM)
Task Group
me:
October 30, 1086
Fm.
Adoinirttstot
!2?:
70.
Assooittt
Administtrtot
for:
Avirtlon
Strndatds
Asroofrtt
Administtrtot for Air
Terff$o
Chief
CounStl
Dlttotot
of
Avlrtlon
Ssftty
Assistant Admlnlsttstot of
Publio
Affrlrs
Diteotot, Attonautiosl Center
In
September
I
dlttottd
thrt
8 TCA
Rtvlew
Task Group
errmint
tht
site,
shspt,
ttsfflo
shunt,
ooapltxity,
Dumber,
type
of flight
infrsotlons,
post
l nfototmtnt efforts
,
and
8ny
other!
f8OtOtS
whloh would allow
the
FAA to
loptovt
ttrfflo
flow and srft
repsration
within
8nd
8rOUnd
TC*A7gi
The
Trsk
GROUP
~88
asked to
provide
me with
teoommtndstlons
whloh would
tnh8nOt
the
tfftotiveness of
the
TCA
oonoept.
On
Wtobtt
15
the
Task Group
submitted an extensive
list
of
teaommendttions
Lnvolvlng
TCA
design, ATC ptootdutts,
taforotmtnt,
8n.d
pilot l duostion.
After reviewing
the
proposed
ttOOm8tnd8tiOn8,
I
hrvt
determined
that
the
following require
rotIon:
/
1.
Adopt
strndstdiztd
ptooedutts
foriWeoking
TCA
intruder
sitotrft
to lnolude
hsndoff
between
8djeaent
ATC
froltitits
8nd
8eotots.
(AAT)
2.
fnvtrtigste
the
potent181
for
lmptax+atnt
in
the
tetmlnsl
8nd
en
r?OUte
8UtOmStiOn
System
tt8okin(-
,orpsbi1lty
to
t8g
ptiorty
8nd
oode
1200
btroon
t8rgets.
(AAT
1
3.
Pxsmlnt
the
potent%81
for:
inoluding
l utomstlo
dtttotsng
-monitoring and ttsoking of intruding
rlmtrft
in rdvsnotd
rutomstlon
sptaiflostlons.
(AAT)
-89-
APPENDIXG
4.
Utilize
the
oapabllity
of
Uodr
S equipment to
rrrlgn
a
dirOBete
trrnrponder
oode
to
eaob
Node S equipped
alror;aft
to
identify
airoratt-
rhioh
are
not
oomplying
with
FAR
91.90.
(AAT)
5,
Reduoe
the
prooerrlng
tlmc
for ohanges in alroraft and
pilot registration
i/oordr.
(MC)
6.
Consfder
inorerred
penrftler
for providing FAA
false
infomrtlon
pertaining to
alnoraft
registrrtlon
and pilot
oertifieate
lnformatlon.
(AGC)
70
Establish a prooedure for notifying the reporting
oontroller
of the final outooae of
mn
enforosmcnt
ooflon
for
8
TCA
v%olrtion
wported
by the
oontroller.
(AGCIAAT)
8,
Exsmine
the established
ptooedupes
for
initial
and
followup
rubmission
of
Inoident
Report (FAA
Fora
6020-5)
and
other:
infolWrtion
fT!oQ
the
air
traffio
faoillty
to the flight
8tandrrde
offioe,
and provide
reoomoendrtlonr
a8 to how to avoid
routine
rubmisaion
of full
dooumentation
before
it
18
neoessrry.
I[n
rdbition,
evrfuate
the possibility of
brving
two
ATC facility
perronnel
oertlfy the oopy of
voloe
tapes to be
used
in
enfotoeaent
rations
in
order: to
en8ure
tbrt at least one
employee
will
be available for
eritoroeoent
hearings.
tAGC/AAT)
9.
&xrmlne
the potent181 for
automatlo
plotting l nU extraotlon
of ARTS XII
drte
if
8uoh
datr
are neoessary for TCA
enforoement
aotions.
(AAT)
Ensure
thrt
en Inoldent Report
$8
filed on all TCA-related
ot
deviations and that Safety Improvement Report8 are filed
only when
wrrranted.
(AAT)
10,
Suspension
orders
for
T.Ci
violations should require that
the pilot
pass an FAA written test on
oontrolled
l lasproe and
dunes
before the
ruspanrlon
1s
lifted.
The
rurpenslon
not be less than
60
days and would oontlnue until the
asses the written test.
(Acic/Avs)
fn
oases where
tile
lnspeotor
determines
that there 18
istlon
as to
the
pilot’8
oompetenoy
at
aavlgrtlon,
the
a
n
rhould
require a
Seotlon
09
Requalifioatlon
Cheek
atlon
oompetenoy in
additiom
to
.the
600dry
ruspenslon
em
test
nequirement.
~Aoc~Avs~
.
suspension of piloting privileges
bon
lore
than
ny TCA violation whioh results in a Near
Nldair:
olassified
as
~orltioal”
or:
npotentlal
APPENDIX G
-9o-
14.
fnltlote
8
l tudy to determine the l ffeotlvwmar of
the
wforoement
polloy
on
penoltler
for?
TCA
riolotlonr.
The
target
dote
fort
oocpleti&'of
the
8tudy’i8
Se#teobet
30,
1987.
(ASF)
15.
f88Ua
monthly
p~e88
mle88cr
on the l nfosoment l 888ure8
Old
type8
Of
8OnOtiOn8
l dQini8trred
t0
TCA
ViOlOtO?8
when
the
number
Of
l OtiOn8
wOrtont8
8
pm88
F8leO8e.
(APA~AGC)
16,
Simplify l nd
8trndrrdlte
TCA
de8lgIi
18
muoh
08
ptootiorble;
Develop new TCA
de8ign
or;.ltwio
and
olRoulrte
for
publio/industry
ooamentr.
COIi8aber,
the
fOllPUi!i~
08
pot8nti81
OldteFlrt
l *
Top8
Bf
oil
TCA'r
l t 10,000 feet
ML
or
7,000
feet
AGL,
whiohever
18
higher.
(AAT)
b.
LOt8r81
limit8
30
mile8
f'rO6
the
p~ibO?y
8ippO?t.
(AAT)
00
Inner?
rurfroe
aRea
of
TCA’r
r~moxlmu~~
of 10
mile8
CEom
the
priaory
airpoet,
OOn8i8tWt
u&th
mnwoy
rlignmnt.
(AAT)
d.
300 foot
per!
aoutl;;:T:ih
#8rUient
fnoa
the
inner:
Ore0
Out
t0
20
dfe8.
e.
Ama
between
20
and 30
mile8
8hould
be
oonrirtent
with
l pproroh/d8p8rtune
pFoOedu?er.
(AAT)
17.
Expedite
Aulemoking
to l 8trbllrh one type of TCA in
line
with
WAR l ttabll8hment
orlterl8
and
rosad
PAd
91.90
l
oootdingly.
(AAT)
18,
f88ut
rpproprirte
ruleooking
not1088
p?opO8in~
the
following new
tequlwm8ntr:
0.
Require on operating
Wodt
C
tFon8pOnder
in
oil
l lrspooe
fFoa
the
8urfroe
to
f2.590
feet
USL
within
30
afler
of
the
p~:irory
TCA
l
l~po)c~.
(AATfAGCfAVS)
Extend the
fixed-win&
l
iro~:rit
equipment
sequiracents
ii
bellobpterr
operating in
TCAQ.
(AAT/AGCfAVS)
Extend the equipment
requtwmptr
oontolned
in
r";,
91.90(r)
to
all
rlnoheft
opewW%ng
wlthln
all
TCA’r.
(AhTfhGcf~v~)
d.
fnitlote
culemokin&
to
pvvpos%
hequ1tit.g
the pilot in
oommrnd
of
a
01~11
biror?mft
ope?8tWtg
irlthln
a
TCA to bold
a
private pilot
oettlflorte
or
hi&-her?.
CAVSfAGC)
-91-
APPENDIX
G
19.
Evaluate
eooh
exirting
TCA to determine
if
the
troffio
oonditions'urrron~~)strlotion
OP.
pnohibltion
of VFR
tP8n8it
through
tht
oeto.
-
Provide
8ptCiffiO
ATC
oontrolled
VFR
tvonrlt
_
stoutts
through those
TCA’s
able
to l ooommod8te that l otlvlty
-’
otftly.
(ALIT)
s
28.
Exomlnt
the
feoslbility
of
inatolllng
8
VORTAC
(VOR/DHE)
on
taah
TCA
pPltB8ry
OiPpoPt.
If
ftrsibte,
utilize
VOR/DPIE
and
omsslng
rirdlol
definition for TCA
bOUnd8Pit8.
(AAT/ASF)
21.
Develop
blselint
d8t8
and
On8ly818
methods
fOP
QV8lUOtiOn
of
TCA's
to lnoludt
u8er
attitudes, knowledge of
TCA’8,
YMAC
data,
pilot dtvlotlon dote,
and
optPotion
l PPOP dote
(post
1985).
Determine the
.numbtr,
and
type
of
lntrurlonr
into
sptolfio
TCA’r.
(ASF)
22,
T8kt
aotlon
to
bimpllfy
and
8tondordlzt
Oh8PtlBg
whloh
defines TCA
boundoPles.
(AAT)
evelop
odvlso~y
0i?0~18t
m8ttPlOl
that
ldtntlfie8
top188
aovertd by Certified Flight
Inrtsuotocs
(CFI)
and
others
odminl8terlng
Biennial
Flight
Review8
(BFR).
The
ubt
of
nd
other
oontr?olltd
OlPSp8Ot..8hO~l
be
8
toplo.
(AVS)
24.
Initiate 0
negul*tory
PequlPemtnt
fat
cF1’8
to report the
ocmpletlon
of 011 BFR to
the
FAA.
The
purpose of
the
report
would be to affirm
thrt
a pilot
h8S
p8Satd
the
BFR
and
has
dtmonstrrted
satlsf8ototy
knowledge of
the
topio
art88
idcntffied
In
advisory
alr;oulor8
pnopostd in
Rtoommtndotion
24
b8V!c
e
(AVS)
Establlrh notlonrfly
~tondordlted
ptooedurts
wh$ah
would’
W2iOuPZ!igt
p8PtiOipPtiOn
Of
Oir:
tPOffla
OOntPOl
8ptalOll8t8
mil%rr
with TCA operations
in
pilot training
8emlnor8.
{AAT)
X~ml~@
nd
dtttrmin@
the
feasibility
of
u8lng
'~8ttwoy"
virsry
oe~viots
to provide TCA
oirrprot
infoPcotlon
tot
proaohfng
TCA
boundorier.
(AAT)
Exrmint
and
dttttmlnt
the
ft8Slbl~ity
of
utilizing
0
oalated
with
Pilot
Jut0
B
Telephone Weather
trvlat
(PATWAS),
for!
pr
lng
pilots with
rpeoifio
n
infomrtion
through
8
rttd flight
8t!!ViOt
tAAT)
xtt~fn@
tht
pOttntiol
benefit Of
lnOPt8sing
the
pO88lng
em written tests to
0
gP8dt
higher
than
Updttt,
8nd
P@pPlnt
for
di8tributlon,
A%t
Ctrricr
8-78-3
(“Importrnot
of Cockpit
Crew
Mtmbtnr
(AWS)
APPENDIX G
-$2-
30.
Exomtne
011 l xi8tlng,lnformrtion l volloblt
io
the
airmen
regarding TCA
ombttpt,
dtriln,
ptootdureo,
eta.,
and
determine
if
that lnformotlon
is
adequate.
Vpd@tt
both
the
oontent
and
mtthOd8
Of
di8tPibution
where
nt,at88ory.
tAVS/AAT,
31.
Develop
8
8t8nd8?dlttd
rtfreshtt
fPoinlng
pPogroi.for
Air
Trofflo
and
Flight
StOndOPd8
ptr?ronnta
whlah
highlights
their
Pt8ptotlvt
responslbllltlts
to
the aviation
oommunlty
regarding
VFR operations in
and
around
TCA’r.
(AVS/AAT)
32.
Evrlurtt
the
ftosiblllty
of utilizing
ttrmlnol
l nhonotd
target generator
trolnlng
programs
to,loprov’t
the
ooatsol
and
ooordlnotlon of VFR pop-up trofflo
Ptqutsting
TCA
8ervlae.
(AAT)
33.
Take
rttps
ntatssory to l n8uPt that 011
air
tPofflo
foollltits
provide
the
?equlPed
TCA training to pertinent
personnel.
(AAT)
34.
Take
8ttpS
ntotr88ry
to
tn8uPt
thirt
the
Oktrh@lar
City
Dtslgnrttd
Exrmlntrz
(DE3
tt8m
provides
updrttd
lnformrtlon
to
DE’s
and
ttbts
DE’8
knowledge of
WA’8
and
other oontrolltd
l
lPspoot .
(AVS)
35.
Take
8ttps
neoe88ory
to
tn8ure
$b#t
Derlgnottd
~xomintr8
test 011 l lrm8n l ppllo8nts on their
knwltdgt
of
TCA’r
and
other
oontrolltd l lrspoot.
(AVS)
36.
Ensure
thrt
811
cFf’8
oft
8llp%1iC?
with
TCA’s
and
other
oontrolltd l iP8pOOt
prior:
to
bitnnf8l
~PtOtPtiflOOtfOn.
?rovldt
CFI'r
with methods for: use in
trrlnlng
their
rtudtntr
about
TCA’s.
(AVS)
37.
Develop
8
aBook-to-Bo81as~
presen%otlon
whiah
teoohts
whrt
8
TCA 18, how to l aotss
it,
and
how to
ubt
it.
tASF/AVS)
38.
Enoourogt
the l vlotlon industry to
ntqulPt
rptoiol
TCA
OiP8p8Ot
ahtakout
fOP
pilot8
based
wl.t%ln
0
prtsor-lbtd
di8tOI¶Ot
fnom
TCA
pPfSl8Py
l
:l?pOPtS.
(AVSIAAT)
-
39.
Evaluate the
extent
of
iddlt%onol
:retouPots
ntots8oPy
to
4ooaoxtplish
the following:
l *
Use of
dedlorttd
personnel
tv
monitor
rode?
for
TCA
VfO~OtOP8.
(AAT)
b.
g8tob~irhatnt
of
poritlon
dt~orlpt~ons
l uoh
08
*OSSi8t8nt8"
OF
wttohnfo18n8~
to
#wlp
handle
invtsltgotlonr
and
vlolotlon
0888
ptep8trtlon
8%
FSDO’r,
(AVS)
-93-
APPENDIX G
.
fnOPtSit~‘8t8ffin~
at
ii?
tr?tfflo
fSOllltie8,
Flight
:;.ndardr
Di8tPiot
Offlots,
and
Rtglonol
Counrtl
offiotr,
08
nt00CS88ty, $0
hrndlc
inOPtOSeS
In
tnfo~otmtnt
oo8t8
due
t0
WIIphO8f8
On
TCA
VfOi8tOP8.
(AAT/AVS/AGC)
d.
~strblishmtnt
of
an
expanded
radar
strvloe
(ERS)
position
st
eroh
TCA
loortlon.
It
1s
oonttmplottd
th8t
this
pO8itiOn
would
fu?IOtlOn
OS
fOllOW8:
All
VFR
oiRor!rft
requesting entry into
the
TCA would
be
required to oontrot
this
oontroller
for idtntlflootlon
ond.to
state
lntentlon8.
The
ERS
oontnolltr
would
oonstontly
evolurtt
trrfflo oondltlons
and
deny
or
approve
entry into
the
TCA.
The
olrorrft
would then
be
handed off to
the
opproprlott
rector oontrolltr.
This
RRS
oontrolltP
oouZd
0180 monitor,
t+rOk,
and
rtoord TCA
lntru8lons.
The duties of
thi8
ERS
position would
be
rlmilo~
to
the
duties
of l porltlon
now
in
use In the Wew
York
TRACON.
(AAT)
soh
offioe
responslblt
for the
di8position
of
one
or
more
of
hcse
reoommtnd8tions
ah811
report its intended
rotion
and
fleatones
to me no
later
than
Wqvtmbtr
15.
As
AAT
ho8
the
8-t
of
the
sotlonr,
I hive
08ktd
thrt
offlat
to trook
this overall effort
and
to
keep
me l bPt8St of the
progrtss
mrdt
tQw8Pd
intended
miltStOnt8.
nald
D. En
APPENDIX G
-94-
STATUS OF FAA
RBCOMMENDATIONS
According to the FAA, as of May 14, 1987,
a&ion
has been completed on
recommendations 2, 3, 4, 5, 9,
100l3,
15, 19, 29, 28, 29, and
3159.
Although
recommendations 2, 3, and 9 were classified as completed, the actions contained therein
will not be implemented until the Advanced Automation Systems
(AAS)
are placed in the
TRACONS.
According to the National Air Space
(NAS)
plan, installation of the
AASs
is
scheduled to begin in 1994 and to be completed in 1997.
Recommendation 4 requires mode S transponders for compliance.
lhe
first
operational mode S is scheduled for March 1, 1990.
‘Ibe
projected date for full mode S
coverage in the
6ontinental
U.S. is January 1, 1997.
Recommendations 17 and 18 require rule action for completion.
‘Ihe
required
Notices of Public Rule Making were issued on June 6, 1987, and publication of the final
rules in the Federal Register is scheduled for November 1, 1987.
Except for recommendations 21 and 24, action on the remaining recommendations is
scheduled to be completed by December
31,1987.
Action on recommendation 24 requires the initiation of a regulation.
Action on this
proposal has been made a part of the Office of
Eliiht
,Standards
regulations review of 14
CFR Parts 61, 141, and 143.
This recommendation will be considered during this
remaking
project; however, milestone dates for the project have not been established.
-95-
APPENDIX H
MID-AIR AND NRAR MID-AIR
SAFRTY
BOARD
RRCOMIURNDATION
HISTORY
Since 1967 the Safety
Board
has issued 116 recommendations as a result of
investigations of mid-air or near mid-air collisions and special studies/investigations of
mid-air
acqidents.
Due to the sheer number of recommendations on this subject, the
recommendation data base was initially reduced to include only cases involving air carrier
aircraft. The unselected recommendations were then reviewed to determine whether they
addressed issues that were appropriate to the accident at Cerritos, California. Accidents
in this group involved
midair
collisions or near mid-air collisions between general
aviation aircraft and military aircraft, general aviation aircraft and corporate aircraft,
general aviation aircraft and air taxi/commuter aircraft, and only general aviation
aircraft.
Additionally, recommendations that resulted from accidents involving air
carrier aircraft but which addressed unique or site-specific issues were not included in the
data base for this appendix. This review resulted in identifying 56 recommendations from
17 accidents over a
19-year
period that are pertinent to the accident at Cerritos. These
recommendations are as follows:
a result of its investigation of an accident of a mid-air collision involving a
alps
World Airlines DC-9 and a Beechcraft Baron near Urbana, Ohio, on March 9, 1967,
the Safety board issued the following recommendation to the Federal Aviation
Administration (FAA):
A-67-25
Survey the types of general aviation airplanes equipped with solid
type visors to determine the extent of the resultant vision
impairment; where it is found that they severely hinder the pilot’s
vision, the solid visor should be replaced by a see-through type;
additionally, we recommend that, if this survey shows the solid
type visors adversely affect the visibility from the aircraft,
Part 23 be amended to provide that when a sun visor is installed on
future airplanes, it be a see-through type if it can be positioned so
that it extends into the area of vision necessary for collision
avoidance.
November 9, 1967, the FAA informed the Board that. it planned to survey
of general aviation fleet equipped with sunvisors to determine the extent of the
vision impairment. Based upon this
rvey,
the FAA issued airworthiness
d~e~t~ves
where applicable and an advisory
circu
cautioning pilots on the judicious use
of
s.
The Board found the
FAA’s
action to comply with the intent of the
ret
atbn and it was classified as “Closed--Acceptable Action.”
Following the Board’s investigation of a mid-air collision at St. Louis, Missouri,
reh
27,
1966, between an Ozark Airlines DC-9 and a Cessna 150, the following
mendation was issued to the FAA:
APPENDIX H
-96-
Ad8-12
A.
‘Ihat
daylight radar display equipment be installed in the
Lamber field tower cab at the earliest possible date.
R.
That greater utilization of the facility radar, be made so as to
provide radar sequencing, monitoring, and advisory service on a full
time basis until phase
II
of the national terminal radar service
program can be implemented at St. Louis.
C.
That VFR patterns (entry points, tracks, and altitudes) be
established for the
Lambert
Field control zone to be utilized by
those aircraft not participating in a radar program.
D. That all of the above recommended actions be considered for
their applicability to other locations similar to St. Louis. Should
you or the members of your staff require additional information on
this matter,
Board
personnel will be available for assistance.
On June 28, 1968, the FAA responded that it had: installed bright tube radar
displays at St. Louis, included St. Louis in Stage
R
of the National Radar Program,
established VFR entry and departure routes for
Lambert
Field, and had identified and was
taking action to correct airports that had problems similar to St.
Loui&
Lambert
Field.
‘lhe
Safety
Board
continued to monitor the
PA,A%
efforts to comply with this
recommendation and on January 1, 1985, classified Safety Recommendation A-68-12 as
llClosed-Acceptable
Action.”
On July 19, 1967, a Piedmont Airlines 727 and a Cessna 310 were involved in a
mid-air collision near Hendersonville, North Carolina. Following completion of its
investigation, the Safety
Roard
issued the following recommendation to the FAA on
September 20, 1968:
A-68-26
1.
lmprove ATC communication methods and procedures for
lFR
in
nonradar
environment.
2.
Expedite increases in ATC radar coverage.
3.
Establii more stringent requirements for pilots using IFR
system.
4.
Require an annual proficiency flight check for all IFR pilots.
In
response to the first two parts of this recommendation the FM said that it
would make improvements to the ACT system and expand radar facilities as budgetary
limits provided. On March 18, 1971, the FAA informed the
Board
that it had started
rulemaking action that would require experience and qualification requirements for pilots
serving as second in command and annual proficiency checks for pilots in command for
aircraft certificated for more than one pilot. The Safety
Board
found this action to be
acceptable and on May 7,
1971, this recommendation was classified as “Closed--
Acceptable Action.”
APPENDIX H
-98-
12;
Reevaluate visual oonspicuity standards for all civil aircraft;
13;
Consider the establishment of requirements for the
installation and day and night operation of high-intensity
white flashing lights on all
civi$
aircraft.
14.
Support the expeditious
deve.&pment
of low-cost Collision
Avoidance Systems for all civil aircraft.
On October 23, 1969, the FAA wrote the Roard stating that the subject of
mid-air collisions required more attention than could be addressed by this
recommendation.
‘Ihe
Roard agreed and decided to hold a public hearing to better
identify areas where immediate action was needed. Safety Recommendation A-69-18 was
subsequently classified as
nClosed-Reconsidered.lV
On
November 4, 1969, the Roard convened a public hearing on the subject of
the prevention of mid-air collisions.
The
following
rpcommendations
resulted from that
hearing and were issued to the FAA on January
30,197O:
A-70-6
Convene a government/industry meeting to specifically examine
the factors involved in establishing the need for standard traffic
patterns.
A-70-7
Review the Chicago terminal area notice in Part 3 of the airman’s
information manual with a view to the expedited development of
similar charts for other terminal areas wherever the mix of
aircraft warranted.
A-70-8
Require FAR pilots be given ground training scanning patterns to
optimize aircraft detection and thus make more productive the
pilot time spent when looking
outside
the cockpit. The
Board
further recommended that detection training equipment be
developed on a priority basis and made available for private pilots
also, as their need for such training was as important as that of
commercial pilots.
Tn
its letter
of
February
9,
1970, the
FAA.
informed the Board that it was in
the process of developing and distributing copies of terminal area charts for 22 large
airports and selected medium airports where there
was
a considerable mixture of traffic.
Rased
upon this action, Recommendation A-70-7 was classified as “Closed-Acceptable
Action.
”
-99-
APPEND& H
Qn
January
21;
1972;
the FAA informed the Board that it did not plan to
require that pilots be given ground training in visual scanning patterns because training
devices for such training were not readily available. However the FAA did plan to
work
with flight schools in encouraging them to incorporate visual scanning in their programs.
The
Board
upheld its position that the FAA should require such training and subsequently
classified Safety Recommendation A-70-08 as “Closed--Unacceptable Action.”
In
February 1975, the FAA provided the
Board
with a copy of Advisory
Circular
90-66,
which recommended standard traffic patterns. The Safety Board found
this action to be satisfactory and classified recommendation A-70-6 as “Closed- -
Acceptable Action,” on October 1, 1975.
Cn
February 22, 1971, the Board issued an additional 11 recommendations to
the FAA as a result of the
Board’s
November 4, 1969, public hearing on the cause and
prevention of mid-air collisions.
These
recommendations are as follows:
A-71-5
Evaluate the pilot qualifications and minimum airborne equipment
necessary for safe operations into high-density terminal areas with
a view toward increasing the minimum standards for each.
A-71-6
Accelerate the program to provide separation between high- and
low-performance aircraft in
highdensity
terminal areas.
A-71-7
Encourage the expeditious development of a collision avoidance
system for installation in air carrier aircraft and larger general
aviation aircraft.
A-71-6
Make funds available for the ground equipment which
‘may
be
necessary for support of CAS systems.
A-71-9
nsor developmental contracts for pilot warning indicator
(PWU
systems utilizing various technological methods in order to
evaluate the practicality of each.
A-71-1 0
velop
regulations to require the installation of CAS and PWI
systems when they become available from the activities of 2 and 5
supra.
APPENDIX H
-lOO-
A-71-1-1
Consider convening a special
Government/Industry
meeting for the
purpose of discussing the factors involved in establishing standard
traffic patterns and initiating action leading to their creation.
A-71-12
Amend the pilot training requirements in the Federal Aviation
regulations to require the addition of scanning techniques to the
training syllabus.
A-71-1 3
Require suitable training aids be used to augment the syllabus when
such aids are developed.
A-71-1 4
Promulgate regulations to require the installation of white
anticollision lights on all aircraft as soon as possible.
A-71-1 5
Accelerate its efforts in developing certification, procedural, and
rulemaking processes involved in implementing a full area
navigation
(RNAV)
system for utilization throughout the
U.S. National Airspace System.
In response to recommendations A-71-5 and -6, the FAA informed the
Roard
that the requirements for group I and II terminal control areas would provide for increased
pilot qualifications, airborne equipment, and aircraft separation.
‘lhe
Board
agreed with
the
FAA%
actions and these two recommendation were classified as “Closed-Acceptable
Actionon
In response to recommendations A-71-7, -6, -9, and -10, the FAA informed the
Board that it had established an
indWry/government
cooperative program to develop and
flight test pilot warning indicators and collision avoidance systems. Funding for these
efforts was included in the FAA’s lo-year plan. The FAA informed the Board
that
as the
necessary equipment and installation requirements matured, regulations would be
developed to require the installation of these systems. Safety Recommendations A-71-7
through -10 were classified as “Closed-Acceptable Action.”
With regard
to
rscommendation
A-71-11,, the FAA had held several meetings
with user groups to discuss establishing standard traffic patterns. The
Board
found this
action to be satisfactory and subsequently this recommendation was classified as
“Closed-
-Acceptable
Action.n
In response to recommendations A-71-12 and 13, the FAA stated that it had
issued a Notice of Proposed Rulemaking on this subject, and that the comments received
either opposed the proposed rule or requested that additional research and development be
accomplished prior to further action being taken.
In
its evaluation the Board noted that
these recommendations were similar in intent to recommendation A-7- 8 and therefore
closed recommendations A-71-1 2 and 13 as “Acceptable Action.”
-lOl-
APPENDIX D
In response to recommendation A-71-14; the FAA issued a new rule requiring
the installation of anticollision lights and a minimum intensity level for anticollision lights
on new aircraft.
Based upon this action, recommendation A-71-14 was classified as
nClosed-Acaeptable
Action.”
In
its letter of March 25, 1971, the FAA informed the Board that it had revised
14 CFR parts 71 and 75 concerning the designation of area low and area high navigation
routes and that approximately 150 routes had been developed.
‘Ihe
Safety
Board
accepted
the FAA action as responsive to the intent of recommendation A-70-15 and therefore
&ssified
the recommendation as
llClosed-Acceptable
Action.11
Upon completion of its investigation of a mid-air collision near Fairland,
Indiana, on September 9, 1969, involving a McDonnell-Douglas DC-9 and a Piper PA-28,
the Safety Board issued the following recommendation to the FAA:
A-70-9
d
had recommended that Parts 21 and 23 of the FAR be
modified to require all aircraft under 12,500 lbs., manufactured
after some appropriate date, to possess a radar cross section
suitable for primary target detection, the Board was now of the
view that a more appropriate regulatory approach would be to
amend Part 91 of the
FAR%
to require all aircraft operating in
radar service environments to have a minimum level of radar cross
section, such action should make it possible for some operators,
never intending to operate in radar environments, to avoid the
necessity of reflective augmentation.
The FAA response to this recommendation was that effective June 25, 1970
t
(
nders were required on all airplanes operating within group terminal control areas
While the
Board
agreed that’ the requirement to have transponders was
eommendable, it did not satisfy the intent of this recommendation that radar target
improved in all radar environments, not just the
TCAs.
On January 11, 1974,
ified this recommendation as
llClosed-Unacceptable
Action.11
As a result of the January 8, 1971, mid-air collision involving an American
es Boeing 707 and a Cessna 150, over Edison Township, New Jersey, the Safety
issued the following recommendations to the FAA:
A-71-58
The Administrator establish
procedures
whereby all operators of
civil flying training schools will formally advise appropriate
Federal Aviation Administration authorities of the locations and
dimensions of designated practice areas for student flying training,
and that such information be disseminated to all affected services
within the FAA.
APPENNDIX
H
-102
-
A-72-104
Assigned altitudes should be maintained as precisely as possible.
A-72-105
Visibility and separation from cloud distances should be assessed
conservatively in VFR operations, and that VFR
fl&ht
should be
continued only when visibility is unquestionable.
In
response to recommendation A-71-58, the FAA issued order 7410.1, which
applied procedures for the establishment of certificated flight school practice areas.
Additionally, the FAA notified instructors of this problem through the FAA flight
instructor refresher clinics. Safety Recommendation A-71-58 was classified as “Closed-
Acceptable Action,” on June 4, 1975.
No response was required for recommendations A-72-104 and -105 because
these recommendations were
intented
to be advisory. For bookkeeping purposes only, they
were classified as “Closed-Acceptable
Action.n
Following the
Board’s
investigation of a
midtlir
collision involving an Eastern
Airlines DC-9 and a Cessna 206 at Raleigh-Durham, North Carolina, on December 4, 1971,
the Safety Board issued the following two recommendations to the FAA:
A-72-27
Require an exchange of pertinent traffic information between the
control tower and the associated radar approach control facility
whenever a pilot who is operating in accordance with VFR has
requested a service or stated his intended flight operations, Such
exchanges of information should be accomplished on a lower
priority basis than that accorded to the transmission of control
clearances.
A-72-28
Require the pilots of all aircraft equipped with an operable
transponder to have the transponder turned
“ON”
and
adjmted
to
reply on the appropriate mode A/3 code whenever VFR operations
are conducted into, or in proximity to, an airport serviced by a
radar approach control facility.
On April 12, 1972, the FAA responded that the airman’s information manual
.&eady
contained information on the use of transponders in
VPR
operations.
Additionally,
the FAA
issued a rule that required the use of a transponder with mode C capability at 21
of the busiest terminal areas, and at 42 additional
.loeations
improved transponders would
be required.
In
this same letter, the
F.AA
stated that procedures were instituted that
improved the coordination of traffic within
jan
airport traffic area. On
December 14, 1973, the FAA informed the
Board
that 14 CFR Part 91 had been revised
with respect to transponder requirements.
Recommendations A-72-27 and -28 were
classif
ied
as
Tlosed-Accept
able Action.”
.
-107-
APPENDIX H
A-7 8-83
Reevaluate its policy with regard to the use of visual separation in
other terminal areas.
A-7 9-73
Prescribe an appropriate method to do so and require all air carrier
companies and commercial operators to test their pilots
recurrently on
ATC radar procedures, radar services,
pilot/controller relationships, and ATC clearances.
A-79-74
Prescribe a method to insure that all general aviation pilots are
tested periodically on ATC radar procedures, radar services,
pilot/controller relationships, and ATC clearances as appropriate
to their operations.
In its response to recommendation A-78-77, the FAA informed the Board that
it had established a terminal radar service area at Lindbergh Airport and that several
improvements had been made to the airport traffic control equipment. Based upon these
actions, recommendation A-78-77 was classified as
nClosed--Acceptable
Action.”
In it letter of April 17, 1981, the FAA stated that following its evaluation of
t
at major airports it had established 48 additional
TRSAs,
bringing the total number
t
with 26 other locations still under consideration, and that
2
new
TCAs
were added
with another 31 locations still being considered.
‘Ihe
Board found these actions to be
satisfactory and classified recommendation A-78-78 as *Closed-Acceptable Action.”
The FAA disagreed with the
Board’%
recommendations A-78- 82 and -83,
stating that it believed that the use of visual separation in
TCAs
and
TRSAs
is a viable
concept and that complying with the Board’s recommendation would
have”an
‘adverse
effect on the efficient use of airspace and increase delays in the
TRSAs.
@
its evaluation
1896, the Safety
Board
stated that it did not agree with the FAA’s
commendations
A-78-82 and -83 were classified as
nClosed-Unacceptable
nse
to recommendation A-79-73, the FAA issued a change to order
’
r Operations Bulletin, which outlined procedures to be followed by the
ensure that pilots were tested r
urrently
on
ATC
procedures. Safety
ndation
A-79-73 was classified as
Vlo
-- Acceptable Alternate
Action.n
nse
to recommendation A-79-73, the FAA developed a slide and tape
dvises pilot of proper procedures for operating in
TCAs
and
TRSAs.
ommendation
A-79-74 was classified
V!losed-Acceptable
Action,” on
APPENDIX H
-108.
Gn
May
18;
1978, a Cessna 150 and a Falcon Fan Jet collided in mid-air about
35
miles west of Memphis International Airport, Memphis; Tennessee. While this
accident did not involve an air carrier, two of the three
re.commendations
which resulted
from this accident are pertinent to the accident at Cerritos. These recommendations are:
A-78-80
Evaluate operational data for each TRSA location and establish
two categories of
TRSA’s.
Those
locations handling the largest
volume of traffic with automated ATC equipment available should
be designated TRSA I locations.
The
remaining areas should be
designated TRSA II locations.
A-78-81
Require Mode
nCn
transponder equipment for operations within a
TRSA I and Group II TCA and require that a pilot of a VFR flight
traversing a TRSA I establish radio contact with the appropriate
ATC facility before entering the designated airspace.
The
FAA disagreed with the
Board’s
recommendation that two levels of
TRSAs
should be created because such a requirement would add considerable confusion to the
TCA/TRSA
concept.
In
response to the Board’s intent, the FAA stated that its efforts to
increase the number of
TCAs
and
TRSAs
would provide a similar level of safety.
The
Safety Hoard agreed with the
FAA%
assessment.
Safety Recommendation A- 78-80 was
classified as “Closed-Acceptable Alternate Action.”
In response to recommendation A-78-81, the FAA had issued an NPRM that
provided for upgraded transponder equipment.
However, after reviewing the comments
received, the FAA decided that the increased number of group II
TCAs
that require, the
use of transponder equipment would satisfy the
Board%
intent. The Board agreed and
classified recommendation A-78-81 as
Y!losed-Acceptable
Alternate
Action.n
The
Hoard’s
investigation of a mid-air collision of two general aviation
aircraft, a North American Rockwell Aero Commander Model 560E and a Cessna Model
1826,
over Livingston, New Jersey, on November 20, 1982, resulted in two
recommendations pertinent to the accident at Cerritos. These recommendations are:
A-83-54
Consolidate information of visual scan techniques in Advisory
Circular
AC90-48C,
“Pilots
Role in Collision Avoidance,” and
‘information suoh as that contained in the Aircraft Owners and
Pilots association’s program
“Take
Two and
See,”
regarding visual
Scan
techniques, in one or more publications that are referred to by
pilots on a continuing basis.
A-83-55
Include questions regarding visual scanning techniques for airborne
targets in written examinations for pilot licenses.
-105-
APPENDIX H
established a mobile air traffic control navigational air
communication and power system.
The
FAA’s
incident reporting system was improved.
d upon these, actions recommendations A-72-156, -157, -158, -161, and -164
were classified as “Closed-Acceptable Action.” Safety Recommendations A-72-160,
-
162, and -163 were classified as
nClosed-Acceptable
Alternate Action.”
The
Safety
z2dltt
not agree with the actions taken by the FAA with respect to recommendations
-
-
-161, and -165. These recommendations were classified as
“Closed-
Unaccept)able
Action.”
As a result of its investigation of an accident involving a North Central Airlines
Convair
340/440
and an Air Wisconsin DHC-6 over Lake Winnebago near Appleton,
Wisconsin, on June 29, 1972, the Safety Hoard issued the following recommendations to
the FAA:
A-73-27
Develop and publish standards for visual search techniques to be
used by instructors and check pilots on all training, certification,
and proficiency check flights when pilots are operating in VMC.
A-73-2 8
ablish
a requirement for pilots to be trained in the techniques of
time sharing between visual scanning for airborne targets and
cockpit duties.
A-73-2 9
Require that all pilots and flightcrew members training,
certification, and proficiency check forms contain a specific item
on scanning and time sharing.
A-73-30
uire that all pilots and flightcrew members be graded in
scanning and time sharing techniques when training, certification,
and proficiency check flights are
conducted
under VMC.
A-73-31
e
the Hoard of the status of the
FAA’s
evaluation project of
7, 1972, on aircraft conspicuity research and, if that project
not been completed, take action to complete the project on a
priority basis.
APPENDIX H
-106-
A-73-32
Expedite the development and issuance of national standards for
systems to provide protection from midair collisions so that the
industry can proceed without further delay to develop and market
economically viable hardware.
On June 3, 1974 the Safety Board classified Recommendations A-73-27 and
A-7338 as “Closed-Unacceptable Action,” because the FAA had chosen not to develop
the standards and requirements for visual scanning training as intended by the Board.
In response to recommendations A-73-29 and A-7330, the FAA informed the
Board in its letter of June 26, 1973, that the en route inspection forms include specific
items associated with scanning and cockpit vigilance.
‘Ihe
Board
agreed that the en route
inspection forms complied with the intent of these recommendations and classified them
as “Closed-Acceptable Alternate Action.”
In its letter of June 26, 1973, the FAA informed the Board of the status of the
FAA’S
aircraft conspicuity research project.
‘Ihis
action complied with the intent of
Recommendation A-73-31 and it was subsequently classified as “Closed-Acceptable
Action.”
In response to recommendation A-73-32, the FAA informed the Board that all
technical
approaches with the potential for providing collision avoidance were being
investigated. However, the FAA decided not to formulate or issue any standards for
collision avoidance systems since the
FAA’s
main effort was to develop the discrete
address beacon system (DABS). In its evaluation dated June 3, 1974, the
Board
found the
FAA’s efforts to develop DABS to be an acceptable approach and classified
recommendation A-73-32 as “Closed-Acceptable Alternate Action.”
As a result of the Board’s investigation of a mid-air collision involving a
Pacific Southwest
Boeing
727 and a Cessna 172, over San Diego, California, on
September
25,1978,
the Board issued the following recommendations to the FAA:
A-78-77
Implement a terminal radar service area
(TRSA)
at
Lindbergh
Airport, San Diego, California.
A-78-78
Review procedures at all airports which are used regularly by air
carrier and general aviation aircraft to determine which other
areas require
either a terminal
control area or a terminal radar
service area, and establish the
apwopriate
one.
A-78-82
Use visual separation in terminal control areas and terminal radar
service areas only when a pilot requests it, except for sequencing
on the final approach with radar monitoring.
-103-
APPENDIX D
CM
August 4, 1971, a Continental Airlines Boeing 707 and a Cessna 150J were
involved in a
mid-air
collision over Compton, California. As a result of its
,investigation,
the Safety Board issued the following recommendation to the FAA on April
5,1972:
A-72-30
Disseminate this report to all pilot schools and bring this message
to the attention of all flight instructors.
.
The FAA concurred in full with this recommendation and the report was
subsequently sent to all of the FAA-certificated flight schools and ground schools and to
state aviation officials.
This
recommendation was
classif
ied
as “Closed-Acceptable
Action,” on August 30, 1972.
In June 1972 the Safety Board completed a special accident prevention study
that analyzed the commonality of mid-air collisions and that updated the Board’s previous
study on this topic.
The
following recommendations were issued to the FAA as a result of
this study:
A-72-156
Take additional steps through their accident prevention specialists
to alert the general aviation community of the increasing potential
of the midair collision hazard in the vicinity of airports.
A-72-157
1
velop
a total midair collision prevention system approach to
include training, education, procedures, ATC equipment and
practices, and the development of collision avoidance systems and
proximity warning instruments that are cost feasible to the general
aviation community.
A-72-156
ire general aviation aircraft, when equipped, to utilize at all
times
both landing lights and anticollision lights during the
approach and takeoff phases of operation and while operating in
terminal or other high-density areas.
A-72-159
After a designated date, require the daytime use of high-density
white lights on all air carrier a
A--72-160
Expedite the implementation of standard traffic pattern altitudes
at
all
airports.
APPENDIX H
-lO4-
A-72-l 61
Review and reconsider the feasibility of requiring radar reflectors
on all civil aircraft.
A-72-l 62
Expedite the planned implementation of terminal control area and
terminal radar separation of VFR and IFR traffic and examine the
potential benefits of high-speed climb and descent corridor access
and egress therefrom.
A-72-163
Designate high-speed climb and descent corridors between the top
of the TCA (Terminal Control Areas) and the floor of the PCA
(Positive Control Areas) for high density traffic areas.
A-72-l 64
Study the feasibility of
.providing
funding support and
implementation of small mobile control facilities for periods of
high-density traffic operation at uncontrolled airports to reduce
collision hazard.
A-72-165
Develop a system to evaluate the effectiveness of improvement
and developments in midair collision avoidance systems, to assess,
measure, and analyze hazard trends.
Cn
October 2, 1972, the FAA responded to these recommendations.
‘lhe
actions
taken by the FAA included:
Created a media campaign to alert the general aviation community
of the need to be more alert for traffic in the vicinity of airports.
Developed a system approach for the collision avoidance system
and the pilot warning indicator.
Continued research and evaluation of
aircraft lighting.
Developed standardized traffic patterns at uncontrolled airports.
.
Continued funding of a program
30
evaluate passive radar
enhancement for small aircraft.
3
Expedited stage II of the national terminal radar program, and the
‘established terminal control areas and modified ATC procedures to
ensure better separation of aircraft.
Lowered and raised the respective’ floor and ceiling of the positive
control area and the TCA in heavy traffic areas to provide total
positive control.
-109-
APPENDIX H
In response to recommendation A-83-541 the FAA developed an item;
Wollision
Avoidance
n(Seanning
for Other Aircraft, for inclusion in the Airmen’s
Information Manual), and. published several articles with consolidated information on
visual scanning techniques. Safety Recommendation A-83-54 was classified as
Wlosed-
Acceptable Action,” on July 22, 1985.
In its letter of November 11, 1985, the FAA informed the Hoard that it had
included questions on visual scanning techniques in the private pilot tests, and that the
pilot, flight instructor, and ground instructor tests would have questions on
visual scanning techniques included at the next publishing cycle.
Hased
upon this action,
Safety Recommendation A-83-55 was classified as “Closed-Acceptable Action.”
As a result of the
Board’s
investigation of a mid-air collision at San Luis
Obispo, California, on August 24, 1984, involving a
Beechcraft
model
C99
and a Rockwell
Aero Commander
112TC,
13 recommendations were issued to the FAA. Two of these
recommendations are pertinent to the accident at Cerritos. These recommendations are:
A-85-64
edite the development, operational evaluation, and final
certification of the Traffic Alert and Collision Avoidance System
(TCAS)
for installation and use in certificated air carrier aircraft.
A-65-65
Amend 14 CFR Parts 121 and 135 to require the installation and
use of
Traffic
Alert and Collision Avoidance System
(TCAS)
equipment in certificated air carrier aircraft when it becomes
available for operational use.
On May
8,
1987, the FAA informed the Hoard that a Notice of Proposed
initiated to require that air carrier airplanes be equipped with a
n
avoidance system.
In its response of June 4,
1987;
the Hoard
e
FAA’s action to be responsive to these recommendations and
expedite its efforts to the maximum extent possible in order that
implemented
as soon as possible.
Pending further correspondence
y
Recommendations A-85-64 and -65 were classified as “Open-
to the FAA:
the Hoard’s investigation of a near mid-air collision that occurred on
ar
New Orleans, Louisiana, and involved a Lufthansa
Boeing
747
eral aviation airplane, the following recommendations were issued
vise
the
localizer
backcourse runway 19 instrument approach
e or the terminal control area at the New Orleans
onal
Airport to provide a vertical buffer between aircraft
following the runway 19 instrument approach procedure and
uncontrolled visual flight rules
(VFR)
aircraft operating below the
floor
of the terminal control area.
APPENDIX H
-llO-
Review instrument approach procedures at airports
&si
ated
as
the primary airport within a Terminal Control Area
TCA)
or
‘f”
Airport Radar Service Areas
(ARSA)
to identify potential conflicts
involving an aircraft
following
a
pubIished
instrument procedure at
the floor of the TCA or
ARSA
and aircraft operating just below the
floor of the TCA or ARSA and, if indicated, modify the instrument
approach procedure and/or the
TCA/ARSA
boundaries to provide
for positive vertical separation between the aircraft.
A-85-114
Institute measures, including
Handbook
7400.2C
and FAA
coordination bet
ween
personnel
appropriate changes to FAA
Order
8260.19A,
to improve
involved in the design of the
terminal control area and airport radar service area airspace and
those involved in the design of the instrument approach procedures
to prevent the creation of potential hazards to the users of the air
traffic system.
Cn
August 13, 1986, the FAA responded to recommend&ions A-85-112,
-113,
and -114. In regard to recommendations A-85-112 and -113, the FAA stated
that it believed that the existing regulations and published recommended operating
practices were sufficient to separate aircraft and to minimize the potential for
midair
coIIisions.
‘Ihe
FAA stated that no further action would be taken, and the
Board
classif
ied
recommendations
A-85-112 and
A-85-113 as
“Closed--Unacceptable Action,” on October
23,1986.
In response to recommendation A-85-114, the FAA informed the Board
that it had reviewed the existing and revised procedures involved in the design of
TCAs
and Airport Radar Service Area airspace and provided information that the
existing
regualtions
and operating practices were sufficient to minimize the
tential
for midair
collisions.
Subsequently, in its Ietter to the FAA dated
Cctober
2
0
,
1986,
the Board classified recommendation A-85-114 as “Closed--Acceptable Action.”
F
*U.
S.GOVfRNPlECRl
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