Electrical failure and crash into ocean, United Air Lines

Electrical failure and crash into ocean, United Air Lines

Electrical failure and crash into ocean, United Air Lines, Inc., Boeing 72722C, N7434U, near Los Angeles, California, January 18, 1969
Micro-summary: This Boeing 727 crashed into the Pacific shortly after experiencing
an electrical failure on takeoff.
Event Date: 1969-01-18 at 1821 PST
Investigative Body: National Transportation Safety Board (NTSB), USA
Investigative Body's Web Site: http://www.ntsb.gov/
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.
TOOTED AIR LIMES. I N C
BOEING 727- 22C. N7434U
MEAE LOS ANGELES. CALIFORNIA
JANUARY 18. 1969
TABLE OF COMTEMTS
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Synopsis
ProbableCause
Investigation
History of t h e Flight
I n j u r i e s t o Persons
Damage t o Aircraft
Other Damage
Crew Information
Aircraft Information
Meteorological Information
Aids t o Navigation
Communications
Aerodrome and Ground F a c i l i t i e s
Flight Recorders
( a ) Flight Data Recorder
(b) Cockpit Voice Recorder
Wreckage
Fire
Survival Aspects
Tests and Research
Other Pertinent Information
Analysis and Conclusions
Analysis
Conclusions
( a ) Findings
(b) Probable Cause
Recommendations and Corrective Measures
Appendices
A. Investigation and Hearing
1 Investigation
Hearing
2
3 Preliminary Reports
B
Crew Information
C t Transcript of t h e Cockpit Voice Recorder
Attachment
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Page
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F i l e No. l-CCOb
NATIONAL TRANSFOBTATION SAFETY BOARD
DEPAETMEIW OF 'ERAMSFORTATION
AIRCRAFT ACCIDEHT REPORT
UHITED AIR LIMES, INC.
BOECTG 727-22C, ~ 7 4 3 4 ~
HEAE LOS AMGELES, CALIFORNIA
JANUARY 18, 1969
SYNOPSIS
United Air Lines, Inc., Flight 266, a Boeing 727-22C, B7434U, crashed
i n t o Santa Monica Bay, approximately 11.3 miles west of t h e Los Angeles
International Airport, at 1821 P.s.t. on January 18, 1969. The a i r c r a f t
was destroyed and t h e s i x crewmembers and 32 passengers on board were all
f a t a l l y injured.
Flight 266 departed from Los Angeles Airport at 1817 P.s.t.,
and 2
minutes l a t e r reported t o Departure Control t h a t they had experienced a
f i r e warning on t h e No. 1 engine and wished t o return. This was t h e last
communication with t h e f l i g h t . The secondary o r transponder t a r g e t disappeared from t h e radarscope immediately following t h e above transmission.
Thereafter, movement of t h e primary t a r g e t indicated t h e a i r c r a f t continued
t o track a s t r a i g h t course on t h e last assigned heading of 270Â f o r approximately a minute and a half, a f t e r which t h e a i r c r a f t commenced, a l e f t turn.
The t a r g e t then disappeared from t h e radarscope.
The Los Angeles weather report i n e f f e c t at t h e time of t h e accident
indicated TOO f e e t scattered, measured c e i l i n g 1,000 f e e t broken, 2,000
f e e t overcast, v i s i b i l i t y 3 miles i n l i g h t r a i n and fog.
The Board determines t h a t t h e probable cause of t h i s accident was
l o s s of a t t i t u d e orientation during a night, instrument departure i n which
all a t t i t u d e instruments were disabled by l o s s of e l e c t r i c a l power. The
Board has been unable t o determine ( a ) why a l l generator power was l o s t
o r (b) why t h e standby e l e c t r i c a l power system e i t h e r was not a c t i v a t e d
o r f a i l e d t o function.
Safety Board recommendations designed t o prevent t h e occurrence of
similar accidents a r e s e t f o r t h i n d e t a i l i n section 3 of t h i s report.
These recommendations prjmarily involve measures directed toward assuring
( a ) t h a t t h e standby e l e c t r i c a l power system w i l l be e f f e c t i v e l y activated,
e i t h e r automatically o r by t h e crew, i n t h e event of t h e l o s s of all generators,
and ( b ) t h a t t h e crew w i l l have available a t t i t u d e indicator instruments following disruption of e l e c t r i c a l power.
1. INVESTIGATION
1.1 History of t h e Flight
United Air Lines, Inc. ( W ) , Flight 266 was a regularly scheduled
passenger and cargo f l i g h t from Los Angeles, California, t o Milwaukee,
Wisconsin, with an en route stop a t Denver, Colorado. N7434U, a Boeing
727-22C, which was u t i l i z e d f o r t h i s f l i g h t on January 18, 1969, a r r i v e d
i n Los Angeles from Denver a t about 1530 I/ on t h a t date.
-
While B7434U was on t h e ground at Los Angeles, a routine en route
inspection was performed by a UAL mechanic who found t h e a i r c r a f t t o be
serviceable and noticed nothing unusual. This check consists b a s i c a l l y
of an i n t e r i o r and e x t e r i o r visual inspection of t h e a i r c r a f t f o r any
condition t h a t might require corrective action. During t h e period t h e airc r a f t was on t h e ground, r a i n was f a l l i n g intermittently. However, t h e
a i r c r a f t was equipped with a protective canvas shroud designed t o prevent
water from dripping i n t o t h e e l e c t r i c a l bay area.
As indicated i n t h e logbookJ M7434~had been operating since January 15,
1969, with t h e No. 3 generator inoperative. The second o f f i c e r on board t h e
a i r c r a f t during t h e f l i g h t M e d i a t e l y preceding Flight 266 on J a n v 18,
1969, s t a t e d t h a t "inoperative" t a p e had been placed over t h e No. 3 generator
CSD (constant speed drive) low-pressure l i g h t , t h e No. 3 generator breaker
c i r c u i t open l i g h t , and t h e Do. 3 generator f i e l d relay open l i g h t . He a l s o
believed t h a t t a p e was placed adjacent t o t h e No. 3 generator position of t h e
AC ( a l t e r n a t i n g current) meters s e l e c t o r switch.
The UAL dispatcher, who was responsible f o r dispatching Flight 266, was
informed approximately 30 o r 40 minutes before departure that t h e No. 3 genera t o r was inoperative. After r e f e r r a l t o t h e Minimum Equipnent L i s t , which, i n
e f f e c t , s t a t e s t h a t t h e a i r c r a f t i s airworthy with only two generators operable
provided c e r t a i n procedures a r e followed and e l e c t r i c a l loads a r e monitored
during f l i g h t , he approved t h e dispatch.
Conversation recorded on t h e cockpit voice recorder p r i o r t o departure
indicates t h a t t h e crew was aware that t h e No. 3 generator was inoperative.
W procedures prescribe t h a t when only two generators a r e operable, t h e
galley power switch and one of t h e two air conditioning packs should be turned
off before takeoff. These switches can be turned t o t h e "on" position during
climbout when t h e f l a p s have been raised.
F l i g h t 266 was scheduled t o depart t h e gate at 1755, but was delayed
u n t i l 1807 because of t h e inclement weather and loading problems. The f l i g h t
commenced i t s takeoff roll on Runway 24 at approximately 1817. The l o c a l
controller i n t h e tower who observed t h e a i r c r a f t during i t s takeoff run, and
u n t i l it was 400 o r 500 f e e t i n t h e a i r and about 8,000 f e e t down t h e runway,
noticed nothing abnormal.
-I/
A l l times herein a r e 'Pacific standard, based on t h e 24-hour clock.
A t 1818: 13, F l i g h t 266 contacted Departure Control and w a s i n s t r u c t e d
t u r n r i g h t heading two seven zero r e p o r t leaving t h r e e thousand
t o 'I.
f e e t . " 21 The cockpit voice recorder i n d i c a t e s t h a t , at 1818:30, t h e sound
of an engine f i r e warning b e l l was heard i n t h e cockpit. 3/ A t 1819:05,
we've had a f i r e warning
F l i g h t 266 reported t o Departure Control t h a t
on number one engine we shut down we'd l i k e t o come back." This was t h e last
communication with F l i g h t 266. Departure Control attempted repeatedly t o
contact t h e f l i g h t during t h e time period following t h i s transmission but w a s
unsuccessful.
..
". . .
The departure c o n t r o l l e r who was handling F l i g h t 266 s t a t e d t h a t t h e
Approximately 5 seconds
f l i g h t responded t o h i s heading i n s t r u c t i o n of 270'.
a f t e r t h e transmission from t h e f l i g h t r e p o r t i n g t h e f i r e warning, t h e seconda r y o r transponder t a r g e t of t h e a i r c r a f t disappeared from t h e radarscope.
The movement of t h e primary t a r g e t i n d i c a t e d t h e a i r c r a f t continued t o t r a c k
a r e l a t i v e l y s t r a i g h t course on 270° A t 1820:30, when t h e a i r c r a f t w a s about
1 0 miles west of t h e shoreline, t h e . d e p a r t u r e c o n t r o l l e r i n s t r u c t e d t h e f l i g h t
t o t u r n r i g h t t o a heading of 060° but again received no reply. A t t h i s
point, t h e primary t a r g e t movement i n d i c a t e d t h e a i r c r a f t s t a r t e d a l e f t t u r n ,
The
a f t e r which t h e t a r g e t disappeared from t h e scope within two sweeps.'
c o n t r o l l e r a l s o s t a t e d t h a t t h e speed of t a r g e t movement during t h e s e last
few sweeps increased g r e a t l y .
h/
Appropriate emergency procedures were i n i t i a t e d following t h e disappearance of t h e t a r g e t from t h e radarscope. It w a s l a t e r determined t h a t t h e airc r a f t crashed at approximately 1821 a t a point 11.3 miles west o f t h e a i r p o r t .
-51
Two ground witnesses observed an a i r c r a f t t a k i n g o f f from Runway 24 at a
time corresponding t o t h e departure of F l i g h t 266. One of t h e s e witnesses, who
i d e n t i f i e d t h e a i r c r a f t a s a B-727 based on t h e engine arrangement, noticed
nothing unusual about t h e a i r c r a f t as it flew d i r e c t l y over h i s c a r . The o t h e r
witness' a t t e n t i o n was a t t r a c t e d by many sparks, reddish i n color, coming
from t h e r i g h t s i d e and r e a r engine of t h e a i r c r a f t . She observed t h e a i r c r a f t when it was about 1,000 f e e t high and climbing gradually a t what appeared
t o be normal speed.
Another ground witness, who w a s l o c a t e d on a h i l l above Faxadise Cove
(northwest of t h e impact p o i n t ) , observed an a i r c r a f t over t h e water, t u r n '
"21
-
The communications between Los Angeles Departure Control and F l i g h t 266 a r e
s e t f o r t h i n f u l l i n t h e Communications s e c t i o n .
-31
For a t r a n s c r i p t i o n of t h e recorded crew conversation during t h i s period,
see Appendix C.
-41
-51
The r a d a r antenna r o t a t e s a t a speed of 1 5 revolutions p e r minute.
The approximate f l i g h t p a t h of F l i g h t 266, based on t h e departure c o n t r o l l e r ' s
memory c h a r t , i s attached t o t h i s r e p o r t .
t o i t s l e f t , and head e a s t back toward t h e a i r p o r t . As t h e plane "descended
i n t o a t h i c k fog bank, he heard an explosion and saw a f l a s h of l i g h t . A
f o u r t h ground witness w a s d r i v i n g along Malibu Beach i n an e a s t e r l y d i r e c t i o n
when h i s son exclaimed "Look, Dad, f i r e . " The man stopped t h e c a r , got out
and saw a n a i r c r a f t "on f i r e " which seemed t o be coming from t h e f r o n t of
t h e plane. The a i r c r a f t was descending, heading toward t h e a i r p o r t and t h e n
it plunged s t r a i g h t down i n t o t h e ocean. This witness a l s o heard s e v e r a l
"firecracker" o r "backfire" sounds while t h e plane w a s s t i l l i n t h e a i r .
1.2
I n j u r i e s t o Persons
Injuries
Crew
-
Passengers
Others
Fatal
Nonfatal
None
1.3
Damage t o A i r c r a f t
The a i r c r a f t was destroyed by impact with t h e water.
1.4
Other Damage
None.
1.5 Crew Information
The crew was properly c e r t i f i c a t e d and q u a l i f i e d t o conduct t h e f l i g h t .
The captain had r e c e n t l y completed DC-8 t r a i n i n g and F l i g h t 266 w a s h i s f i r s t
f l i g h t i n a E 7 2 7 since December 2, 1968. The second o f f i c e r completed
E 7 2 7 t r a n s i t i o n t r a i n i n g on December 19, 1968, and completed h i s l i n e check
on January 2, 1969. He had a t o t a l of 40 hours as second o f f i c e r i n t h e
E-727, of which at least 18 hours were i n t h e QC model.
The o f f i c i a l medical f i l e s o f t h e f l i g h t crewmembers and interviews with
r e l a t i v e s revealed no conditions which might have adversely a f f e c t e d t h e
crewmembers' f i t n e s s f o r duty.
For d e t a i l e d crew information, see Appendix B.
1.6 A i r c r a f t Information
6
~ 7 4 3 w4 a~s a Boeing Model 727-22C (Qc), -I
S/N 19891, with a d a t e of
manufacture of September 1, 1968. A standard airworthiness c e r t i f i c a t e w a s
issued on September 19, 1968, and t h e a i r c r a f t w a s delivered t o United Air
Lines on September 20, 1968. The a i r c r a f t had accumulated 1036: 47 hours
operating time s i n c e new, including 217:09 hours s i n c e t h e last maintenance
check and 90:01 hours s i n c e t h e last s e r v i c e check.
-61
Quick change, cargolpassenger.
The a i r c r a f t w a s equipped with t h r e e Pratt & Whitney JT8D-7 engines.
Engines No. 2 (SIN 655074) and No. 3 (SIN 655085) had been on t h e a i r c r a f t
since new and had accumulated 1037:00 hours. Engine No. 1 (SIN. 654366) was
a replacement engine with a t o t a l of 4,505 hours, including 1,021 hours s i n c e
heavy maintenance.
The a c t u a l gross weight of M7434~at t h e time of t a k e o f f was computed
t o be 148,800 pounds, as compared w i t h t h e maximum allowable gross takeoff
weight of 156,100 pounds. The c e n t e r of g r a v i t y of t h e a i r c r a f t was calcul a t e d t o have been w i t h i n t h e prescribed limits both at t h e time of t a k e o f f
and t h e time of t h e crash.
A l l of t h e records exmined during t h e course of t h e i n v e s t i g a t i o n disclosed t h a t t h e a i r c r a f t had been m a i n t a i n e d ' i n accordance with a p p l i c a b l e
company and Federal Aviation Administration (FAA) d i r e c t i v e s and procedures.
These records were examined with p a r t i c u l a r reference t o t h e f i r e warning and
e l e c t r i c a l systems.
The records p e r t a i n i n g t o N743kU contained no r e p o r t s of p r i o r f i r e
warnings on t h e No. 1 engine o r of any condition t o which t h e f i r e warning
experienced on F l i g h t 266 might have been r e l a t e d . With r e s p e c t t o t h e
United A i r Lines B-727 f l e e t i n general, a t o t a l o f 73 i n - f l i g h t shutdowns
due t o firewarnings was experienced during t h e period from January 1966
through March 1969. Of t h e s e , only 1 0 were " f a l s e " warnings
i .e.,
warnings f o r which t h e r e w a s no i d e n t i f i a b l e cause such as overheat o r f i r e .
Most of t h e engine shutdowns i n which no a c t u a l f i r e occurred were due t o
overheat r e s u l t i n g from hot, high-pressure engine bleed a i r l e a k i n g i n t o
t h e f i r e warning sensor a r e a through f a i l e d o r cracked ducting.
--
Research i n t o t h e records concerning t h e f i r e warning system a l s o d i s closed t h a t Boeing Service B u l l e t i n No. 26-15 w a s i s s u e d on May 7, 1968,
t o reduce f a l s e f i r e o r overheat i n d i c a t i o n s on a i r p l a n e s using t h e
Lindberg engine f i r e d e t e c t o r system" J/ The b u l l e t i n provided f o r options
replacement of a sensor element designed t o a c t u a t e warnings at 325'
25' F., with a sensor designed t o a c t u a t e warnings at 375'
25' F.. The
system i n s t a l l e d on t h e No. 1 engine on N7434U incorporated t h e 325"
2 5 3'. sensor.
. ..
/
/
/
With respect t o items of i n t e r e s t i n t h e h i s t o r y of t h e e l e c t r i c a l system
on H7434U, t h e No. '3 generator c o n t r o l panel was removed on January 13, 1969,
and replaced with panel S/N 163. The l a t t e r panel had been removed frm e i g h t
d i f f e r e n t a i r c r a f t f o r varying reasons during t h e period from May 2, 1967,
u n t i l December 31, 1968. 8/ Three hours l a t e r , on t h i s same date, t h e crew
-
-7/
This b u l l e t i n w a s i s s u e d i n connection with t h e B-727-200 s e r i e s a i r c r a f t ,
which had an engine n a c e l l e temperature t h a t r a n s l i g h t l y higher t h a n
e a r l i e r versions.
-81
Search o f t h e records a l s o disclosed t h a t Westinghouse Service B u l l e t i n
66-103 (September 1966), which recommended replacement of a s i l i c o n e
c o n t r o l l e d r e c t i f i e r i n o r d e r t o prevent nuisance t r i p p i n g o f t h e
d i f f e r e n t i a l p r o t e c t i o n c i r c u i t r y , had not been accomplished on panel
SIN163.
which brought t h e a i r c r a f t i n t o OtHa.re F i e l d reported: "No. 3 generator
underexcitation l i g h t on b e f o r e generator connected t o bus. Reset f a u l t
but generator f i e l d a f t e r 2 t r i e s s t i l l would not s t a y closed with no load
on generator. Disconnected CSD." The c o r r e c t i v e a c t i o n was t o replace t h e
No. 3 generator. 91 The generating system apparently passed a l l t h e ground
t e s t i n g necessary t o put t h e No. 3 system back i n service. However, 3-112
f l i g h t - h o u r s l a t e r , a crew disconnected t h e newly i n s t a l l e d generator because
t h e f i e l d r e l a y would not s t a y closed. The No. 3 generator was t h e n rendered
inoperative by ground maintenance personnel and c a r r i e d a s a deferred item
i n accordance with t h e Minimum Equipment L i s t .
The No. 3 generator was s t i l l being c a r r i e d a s a deferred item 3 days
and 42 f l i g h t - h o u r s l a t e r at t h e time o f t h e a c c i d e n t . During t h i s period,
t h e a i r c r a f t operated through a t o t a l of 28 s t a t i o n s , 23 of which possessed
l i n e maintenance c a p a b i l i t y . The item was not r e p a i r e d during t h i s period
because o f t h e exigencies of a v a i l a b l e a i r c r a f t and f l i g h t scheduling.
1.7 Meteorological Information
A n extensive a r e a of r a i n , fog, and low cloudiness prevailed along
much of t h e C a l i f o r n i a c o a s t l i n e and i n t o c e n t r a l s e c t i o n s of t h e s t a t e i n
advance of a f r o n t a l system approaching from t h e P a c i f i c Ocean. The 1900
surface weather c h a r t showed, i n p a r t , a cold f r o n t extending southwestward
from near San Francisco i n t o t h e P a c i f i c and a warm f r o n t extending from near
San Francisco southwestward along t h e P a c i f i c Coast near Monterey, Santa Maria,
and San Nicolas I s l a n d .
The o f f i c i a l surface weather observations taken at Los Angeles a t times
most immediate t o t h e accident were a s follows:
Record s p e c i a l , 700 f e e t s c a t t e r e d , measured 1,000 broken,
2,000 overcast, v i s i b i l i t y 3 miles, l i g h t r a i n , fog,
temperature 55' F. dew point 50' F., wind 160° 5 knots,
a l t i m e t e r s e t t i n g 29.96 inches. 101
,
1827
-
-
Special, 800 s c a t t e r e d , measured 2,500 overcast, 4 miles,
l i g h t r a i n , fog, temperature 54' F., dew point 49' F., wind
6 knots, a l t i m e t e r s e t t i n g 29.96 inches.
la0,
The d e p r t u r e c o n t r o l l e r who w a s handling F l i g h t 266 reported t h a t t h e r e
were two l a r g e i n t e n s e weather r e t u r n s on t h e radarscope, one of which w a s due
-91
The generator which was removed from t h e a i r c r a f t was l a t e r examined i n
t h e shop and no discrepancies were found.
A t t h e time of departure of F l i g h t 266, t h e 1755 weather observation was
being continuously broadcast i n t h e Los Angeles a r e a on frequency 118.6
MHz as p a r t o f t h e Automatic Terminal Information Service (ATIS).
west of t h e a i r p o r t and moving eastbound. When t h e primary t a r g e t of t h e
f l i g h t disappeared, it w a s j u s t approaching t h e northern edge of t h i s weather
return.. The c o n t r o l l e r a l s o r e l a t e d t h a t p i l o t s were generally reporting
r a i n showers west of t h e a i r p o r t i n all quadrants. Such reports were cons i s t e n t with ground witness observations.
The p i l o t s of Air West Flight 312, which departed from Runway 24 1minute
prior t o Flight 266, s t a t e d t h a t t h e i r a i r c r a f t entered t h e overcast at 800
f e e t . After crossing t h e shoreline while climbing through 1,000 t o 1,200
f e e t , t h e f l i g h t encountered complete darkness and t h e r e a f t e r w a s without
any reference t o an outside horizon. The f i r s t o f f i c e r on UAL F l i g h t 111,
which departed from t h e same runway h minutes a f t e r Flight 266, reported
entering an overcast 112 mile o f f t h e coast at an a l t i t u d e of 1,000 t o 1,500
feet
.
No weather b r i e f i n g was furnished t o t h e crew of F l i g h t 266 by personnel
of t h e Weather Bureau o r Flight Service Station, Los Angeles, nor w a s t h e r e a
known formal weather b r i e f i n g of t h e crew by company personnel. However, t h e
company maintains a self-help weather b r i e f i n g display a t t h e i r Los Angeles
f a c i l i t y , which under most circumstances i s t h e method used by crews t o
familiarize themselves with current and forecast conditions.
1.8 Aids t o Navigation
Ground c e r t i f i c a t i o n checks, which began about 10 minutes a f t e r Flight 266
disappeared from t h e radarscope, indicated t h a t t h e Los Angeles radar, seconda r y radar gear, and radar display equipment were operating within established
tolerances. Ground checks a l s o disclosed t h a t t h e back course l o c a l i z e r ( f o r
Runway 2 5 ~ )of t h e Instrument Landing System ( f o r Runway 7 ~ was
) operating
satisfactorily.
A f l i g h t check conducted on January 18, 1969, by t h e FAA indicated t h a t
t h e primary and secondary radar were operating s a t i s f a c t o r i l y . A second
f l i g h t check w a s conducted on January 21, 1969, t o determine minimum a l t i t u d e
coverage between 7 and 15 miles west of Los Angeles Airport. The secondary
radar was good a t 500 f e e t i n t h e area, while t h e primary radar w a s good at
700 f e e t and intermittent below 700 f e e t .
1.9
Communications
The communications between Flight 266 (UA 266) and Los Angeles Departure
Control (DC),as recorded i n t h e Los Angeles Air T r a f f i c Control Tower, were as
follows:
TIME
-
SOURCE
1818:13
Vk 266
United two s i x s i x on departure
DC
United two sixty-six Los Angeles departure control
radar contact t u r n r i g h t heading two seven zero
r e p o r t leaving t h r e e thousand
COCTrEBT
Two seven zero Wilco
Ah departure United two s i x s i x
United two s i x t y s i x go ahead
United two s i x t y s i x go ahead
We've had a f i r e warning on number one engine
we shut down we'd l i k e t o come back
United two s i x t y s i x Roger what i s your present
altitude
United two s i x t y s i x maintain three thousand and
say your a l t i t u d e
United two s i x t y s i x say your a l t i t u d e maintain
t h r e e thousand t h r e e thousand f i v e hundred what's
your a l t i t u d e now
United two s i x t y s i x i f you hear do not climb
above f i v e thousand t r a f f i c twelve o'clock t h r e e
miles west-bound l e v e l at f i v e thousand a
F a i r c h i l d en route t o Ventura.
United two s i x t y s i x ah t u r n r i g h t
heading zero s i x zero
United two s i x t y s i x i f you hear t u r n r i g h t
heading two s i x uh zero s i x zero
United two s i x t y s i x i f you hear us squawk two
zero zero zero o r zero four zero zero
A t 1822:05, United Air Lines F l i g h t 111, a l s o departing from Runway 24,
c a l l e d Departure Control and was vectored c l e a r of
t r a f f i c we l o s t
out west." A t 1822:25, departures were stopped and, at l823:50, Departure
Control was informed by United F l i g h t 111 t h a t Flight 266 had not been talking with t h e company.
". . .
The f l i g h t check of t h e Los Angeles radar conducted on January 18, 1969,
a l s o demonstrated t h a t radio communications on 125.2 MHz, t h e frequency on
which Flight 266 was conmrunicating with Departure Control, were s a t i s f a c t o r y
i n t h e a r e a west of t h e a i r p o r t .
1.10
Aerodrome and Ground F a c i l i t i e s
Not involved i n t h i s accident.
1.11 Flight Recorders
(a)
F l i g h t Data Recorder
The a i r c r a f t w a s equipped with a Fairchild I n d u s t r i a l Products
1423, which was i n s t a l l e d i n t h e r i g h t
f l i g h t data recorder, Model 5424,
ventral stairway a r e a aft of t h e r e a r pressure bulkhead. The f l i g h t recorder
was r e c o v e r e d , s t i l l encased i n i t s housing which had collapsed around t h e
recorder. The f l i g h t record medium was readable and showed t h a t all parase t e r s were functioning.
SIN
A data graph was p l o t t e d t o r e f l e c t two separate time periods. The
f i r s t covers t h e period commencing with l i f t - o f f and ending l m i n u t e 34
seconds l a t e r when t h e t r a c e s ceased t h e i r normal appearance and became
widely divergent, indicating an e l e c t r i c a l power interruption. This power
interruption occurred 5 seconds a f t e r t h e completion of a h-second VHP
The
transmission from Flight 266 t o LQS Angeles I k p r t u r e Control.
second time period commenced at an indeteminate l a t e r time and l a s t e d 15
seconds, during which divergent t r a c e s were recorded f o r all prameters.
Examination of t h e data graph reveals that following l i f t - o f f , t h e airc r a f t climbed approximately 2,300 f e e t i n 1 minute 30 seconds at a steady
r a t e of climb of about 1,500 f e e t per minute. I n t h e 4 seconds p r i o r t o t h e
power interruption, t h e a i r c r a f t descended 50 f e e t . The indicated airspeed
t r a c e shows t h a t t h e speed increased s t e a d i l y from 142 knots at l i f t - o f f t o
212 knots l m i n u t e l a t e r . A t t h i s point, t h e airspeed s t a r t e d t o decrease,
reaching 203 knots 13 seconds l a t e r , at which point it s t a r t e d t o increase
again, reaching 217 knots when power interruption occurred 21 seconds l a t e r .
The magnetic heading t r a c e remained on 250' u n t i l 30 seconds a f t e r l i f t - o f f .
It then s h i f t e d gradually during t h e next 30 seconds t o 270° where it
remained u n t i l power was interrupted 34 seconds l a t e r . The v e r t i c a l acceleration t r a c e recorded e r r a t i c excursions i n t h e period following liftoff which tended t o f l a t t e n out i n t h e f i n a l 1 5 seconds p r i o r t o power
interruption.
During t h e second period plotted on t h e data graph, when power was
restored, t h e i n i t i a l t r a c e indications on all parameters were p a r t i c u l a r l y
e r r a t i c . When t h e power w a s again l o s t 1 5 seconds a f t e r being restored, t h e
following readings were being reflected: a l t i t u d e 630 f e e t , indicated airspeed 326 knots, heading 2 a 0 , and v e r t i c a l acceleration / 1.75 G t s .
(b)
Cockpit Voice Recorder
The a i r c r a f t was equipped with a United Control cockpit voice re1670, located j u s t forward of t h e aft pressure
corder (CVR), Model V-557,
SIN
The f o i l record contains two a u x i l i a r y binary t r a c e s which r e f l e c t
excursions when transmissions a r e made on t h e No. 1 and No. 2 VHP
communications system.
bulkhead, on t h e right-hand side of t h e a i r c r a f t . The CVE was recoxered
almost 6 weeks a f t e r t h e accident. Despite having been immersed i n 1,000
f e e t of sea water during t h i s period, t h e CTK yielded a good tape.
covering t h e
A t r a n s c r i p t i o n from a recording of t h e tape w a s
period following receipt by t h e f l i g h t of takeoff clearance a t 1816: 58. This
t r a n s c r i p t i s set f o r t h i n Appendix C. With respect t o t h e recording p r i o r
t o t h i s time, all four channels of t h e o r i g i n a l tape were monitored t o
determine whether there was any conversation r e l a t i v e t o t h e s t a t u s of t h e
a i r c r a f t ' s e l e c t r i c a l generating system, a s well a s other information which
might be pertinent t o t h e accident. The only crew conversation noted i n
t h i s regard was a reference t o t h e inoperative s t a t u s of t h e No. 3 generator,
of which t h e captain was made aware.
At
The CVR indicates t h a t t h e f i r e warning b e l l sounded a t 1.818:30.
1819:13.5, 5 seconds a f t e r completion of t h e transmission from Flight 266
regarding t h e f i r e warning, CVB operation ceased. A t a l a t e r indeterminate
time, t h e CVR resumed operation f o r a period of 9 seconds. When t h e recording terminated a second time, sounds normally associated with impact
were not detectable.
1.12
Wreckage
The a i r c r a f t crashed i n t o t h e Pacific Ocean a t l a t i t u d e 33' 56' 56" N.,
and longitude 118' 39' 30" W., o r approximately 11.3 miles from t h e Los Angeles
VOR on t h e 260' r a d i a l . The ocean depth at t h i s ~ i n i ts approximately 950
f e e t . The general o r i e n t a t i o n of t h e wreckage path w a s east-west, covering an
approximate area 600 f e e t long and kOO f e e t wide. The l a r g e s t sections
recovered, including t h e engines, were d i s t r i b u t e d along a r e l a t i v e l y s t r a i g h t
l i n e bearing 262O true.
Approximately 50 t o 60 percent of t h e bulk of t h e a i r c r a f t was recovered.
Components from all major sections were i d e n t i f i e d i n t h e wreckage. The airc r a f t w a s destroyed by t h e impact, with only small fragments remaining from
a l l sections. The fragmentation and d i s t o r t i o n were most complete toward t h e
nose of t h e a i r c r a f t and t h e right-hand side, and l e s s material from those
areas was identified. Conversely, pieces from t h e left-hand, side and aft end
were greater i n number, l a r g e r i n size, and l e s s mangled.
Evidence i n t h e wreckage indicated t h a t t h e landing gear w a s i n t h e
r e t r a c t e d position and t h e wing f l a p s were i n t h e 2 extended position. The
No. 2 leading edge slat, t h e only slat section positively identified, was
extended at t h e t i n e of impact.
!The condition of t h e s m a l l portion of t h e o v e r a l l electrLca1 system which
was recovered was not considered t o be pertinent t o t h e accident. None of
t h e instruments f r o m t h e f l i g h t panel o r t h e engineer's panel w a s recovered.
All t h r e e engines were recovered within a 100-foot c i r c l e i n t h e main
wreckage area. The No. 1 engine exhibited only minimal r o t a t i o n a l damage,
thus indicating t h a t it was not r o t a t i n g a t impact, which i s consistent with
t h e reported crew a c t i o n of shutting down t h e No. 1 engine. There were no
engine case penetrations, nor was t h e r e any evidence of overheat conditions
present on engine i n t e r i o r o r e x t e r i o r areas. There likewise was no evidence
of gross bleed air duct leakage o r rupture.
Both No. 2 and No. 3 engines had sustained massive r o t a t i o n a l damage and
twisting of low t u r b i n e shafts, indicating high-speed r o t a t i o n at impact. All
t h r e e t h r u s t reverser assemblies were found i n t h e forward t h r u s t position.
Also recovered were two damaged sensor responders which had been mounted
on engines No. 1 and No. 2 and. which constitutedmajor portions of t h e engine
f i r e detector systems. These components were subjected t o extensive functional
t e s t i n g and were found t o be operating within design specification limits.
-
1.13 F i r e
One ground witness reported seeing an a i r c r a f t on f i r e plunge i n t o t h e
ocean, another saw a f l a s h of l i g h t a s an a i r c r a f t descended i n t o a fog bank,
while a t h i r d saw sparks coining from a departing a i r c r a f t . However, t h e r e was
no evidence of f i r e on any part of t h e recovered wreckage, including t h e No. 1
engine and 'adjacent structure.
1.14
Survival Aspects
The complete destruction and extreme degree of fragmentation of t h e a i r c r a f t , p a r t i c u l a r l y t h e occupiable area, a r e indicative of impact forces far
exceeding human tolerance. A p a r t from one severely mutilated body, only body
fragments were recovered and only two i d e n t i f i c a t i o n s (both of which were
passengers) could be .made.
1.15
Tests and Research
An extensive s e r i e s of ground and f l i g h t t e s t s was conducted subsequent
t o t h e accident i n an attempt t o shed some l i g h t on t h e e l e c t r i c a l and associated problems experienced by Flight 266. These t e s t s generally showed t h a t
during one and two generator operations, t h e a i r c r a f t e l e c t r i c a l system could
more than adequately carry t h e design load, provided prescribed procedures
were followed. Tests a l s o showed t h a t e l e c t r i c a l outages have no s i g n i f i c a n t
adverse e f f e c t on t h e f l i g h t control system.
Among t h e more relevant information developed by t h e t e s t s was t h e f a c t
t h a t during c e r t a i n extreme overload conditions, s u f f i c i e n t induced e l e c t r i c a l
interference may be present on some B-727 a i r c r a f t t o i n h i b i t proper operation
of t h e No. 2 time delay c i r c u i t of t h e protection panel. The expected action
of t h i s panel during such an overload would be t o t r i p t h e bus t i e breaker,
thereby i s o l a t i n g t h e generator and load bus from t h e remainder of t h e
e l e c t r i c a l system and clearing t h e overload. However, i f t h e No. 2 time
delay c i r c u i t i s disabled by t h e induced interference, t h e No. 1time delay
c i r c u i t w i l l continue t o sense t h e overload and, a f t e r 5 t o 9 seconds, w i l l
t r i p t h e generator control r e l a y and t h e generator c i r c u i t breaker, thus
removing t h e generator from t h e system. Flight t e s t s indicated t h a t ,
p a r t i c u l a r l y with t h e b a t t e r y switch o f f y t h e generator f i e l d relay would
t r i p p r i o r t o t h e bus t i e breaker i n approximately half t h e time under overload conditions.
It was a l s o attempted, during t h e t e s t s , t o simulate t h e voltage cond i t i o n r e f l e c t e d on t h e CVR at t h e point when power w a s restored f o r 9
seconds. These t e s t s indicated a low voltage condition of 50 v o l t s a t t h a t
time. This power l e v e l was simulated by s t a r t i n g one generator with loading
f o r two generators applied.
1.16
Other Pertinent Information
( a ) UAL Einergency o r Abnormal Frocedures
Pertinent UAL procedures i n e f f e c t a t t h e time of t h e accident
were a s foUows:
Engine F i r e
If f i r e warning l i g h t illuminates s t e a d i l y and b e l l rings:
Phase I
.. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ..
............
..............
Additional UAL Items:
Engine Fuel Shutoff Valve Switch . . . . . . .
...........
ThrustLever
Start Lever
Essential Bower Selector
Engine F i r e Switch
Fuel Boost Pump Switches
Idle
Cut-Off
On Operating Generator
Pull
Close
A s Required
Blase 11
F i r e Warning l i g h t ON:
...........
I f f i r e warning l i g h t remains ON a f t e r 30 seconds:
...........
Bottle Transfer Switch
..........
Bottle Discharge Switch
Bottle Discharge Switch
12/
-
Push
Transfer
Push
Engine f i r e and l o s s of all generators a r e emergency procedures, while
one generator and two generator operations a r e abnormal procedures.
With respect t o emergency proceduresy Phases I and I1 a r e minimum
immediate a c t i o n i t e m s , w i t h Phase I being completed before Phase 11.
Phase I11 i s accomplished as soon as time permits.
Blase I11
Land i f f i r e p e r s i s t s
Two Generator Operation
1. Generator Breaker Switches
Operative Generators
Inoperative Generator
........................
........
Close
Trip
2.
Bus Tie Breaker Switches (3)
3.
If generators cannot be paralleled, operate
generators i s o l a t e d .
4.
I f generators cannot be paralleled and inoperative
generator i s #1 o r #2:
#3 Generator Bus Tie Breaker Switch
. . . . ..
Inoperative Generator Bus Tie Breaker Switch
Remaining Bus Tie Breaker Switch
5.
6.
Close, observing
manual p a r a l l e l i n g
procedure
Close
Close
Trip
......
During takeoff, approach, and landing:
Galley Fewer Switch . . . . . . . . . . . .
A/C Pack Switches
. . . . . . . . . . . . . WOffm u m of one On
E l e c t r i c a l Loads
. . . . . . . . . . . . . . . Monitor
Notes:
a.
Other loads not required f o r t h e p a r t i c u l a r operating
condition should be turned o f f t o l i m i t t h e t o t a l load
t o 57 KVA (54 KW).
b.
Both A/C packs may be operated during Cruise F l i g h t
i f necessary, however, one must be turned OET p r i o r
t o extending Wing Flaps f o r APPROACH and W I N G .
Cargo heat valves should be closed when only one
A/C pack i s operating.
One Generator Operation
1. Generator Breaker Switches:
3.
4.
. . .. .. .. .. .. .. .. .. .. ..
Bus Tie Breaker Switches (3) . . . . . . . . .
.............
Galley Fewer Switch
A/C Pack Switches
..............
5.
E l e c t r i c a l Loads
Operative Generator
Inoperative Generators
2.
...............
Close
Trip
Close
Off
Both OET, p r i o r t o
extending f l a p s
Monitor
Loss of All Generators
Phase I and I1
Any Generator F i e l d Relay
Note:
............
Close
To permit closing generator f i e l d relay when a d i f f e r e n t i a l
f a u l t i s indicated, PULL and RESET t h e associated generator
control c i r c u i t breaker o r place b a t t e r y switch OFF then ON.
Essential Power Selector
............
To Operating
Generator
Repeat i f necessary u n t i l e s s e n t i a l power f a i l u r e warning l i g h t
remains o f f .
Phase I11
Restore system t o normal i f possible.
Apart from t h e t h r e e generators, t h e HAL version of t h e B-727 a i r c r a f t
a l s o has a standby e l e c t r i c a l power system which can be a c t i v a t e d by pos i t i o n i n g t h e Essential Power Selector Switch t o Standby and turning t h e
Battery Switch ON. 3-31 This w i l l provide power f o r t h e captain's gyro
horizon, captain's compass, No. 1 VHP receiver, No. 1 VHP transmitter,
No. 1 Vm, No. 1 glide slope, radio altimeter, and t h e f i r s t o f f i c e r ' s
RMI (remote magnetic i n d i c a t o r ) card. Although t h e action of switching
t o t h e standby system i s not included i n t h e "Loss of all Generators"
emergency procedure s e t f o r t h above, t h e UAL second o f f i c e r on Flight
266 was instructed during t r a i n i n g t o attempt t o close t h e generator
f i e l d r e l a y ( s ) only once before going t o standby.
(b)
Other Incidents Involving Loss of a l l Generators
During t h e months of June and J u l y 1969, t h e r e were t h r e e occasions on which HAL B-727 a i r c r a f t experienced l o s s of a l l t h r e e genera t o r s . The f i r s t of these incidents occurred on June 10, 1969, near
San Francisco and involved a i r c r a f t N7411U. When t h e f l i g h t was appreaching t h e San Francisco LQM i n V i s u a l F l i g h t Rules (VFR) conditions,
t h e second o f f i c e r noted t h a t h i s background f l i g h t l i g h t s were fluctuating. He t r i p p e d all t h r e e bus t i e breakers t o i s o l a t e t h e generators.
He then selected No. 3 on t h e e s s e n t i a l power switch and checked t h e phase
l i g h t s . The l e f t l i g h t was steady, t h e r i g h t l i g h t was flashing, and
voltage was fluctuating. He switched e s s e n t i a l power t o t h e No. 2 genera t o r and l o s t a l l generator power momentarily, although t h e No. 3
generator f i e l d r e l a y remained closed. The second o f f i c e r switched t o
standby power and then r e s e t No. 1 generator f i e l d r e l a y and s e t ese n t i a l power on No. 1 and power was restored. The No. 1 generator
breaker was opened, and t h e No. 2 f i e l d r e l a y and t h e No. 2 and No. 1
13/
-
The B-727 a l s o has an Auxiliary Power Unit (AFU), but it i s operable
only when t h e a i r c r a f t i s on t h e ground.
bus t i e breakers were closed. The No. 3 bus s t i l l remained unpowered
because No. 3 f i e l d relay had opened. The No. 3 breaker w a s closed, and
No. 3 bus t i e l e f t open. A l l power was then normal. After t h e landing,
t h e f a u l t panel showed t h e No. 2 generator was underexcited.
HAL was unable t o duplicate t h e above sequence of events e i t h e r on
t h e ground or i n f l i g h t t e s t s . A number of p a r t s were removed and examined, but t h e reason f o r t h e l o s s of a l l generator power i s s t i l l unknown.
The second incident occurred on a touch-and-go landing a t Cheyenne,
Wyoming, on a t r a i n i n g f l i g h t on June 26, 1969. The No. 3 engine had
been pulled back simulating a two-engine approach. A s t h e t h r o t t l e s
were advanced t o t h e takeoff position, t h e i n s t r u c t o r noted t h a t t h e No. 2
or No. 3 EFR
gauge did not advance a s rapidly as t h e No. 1 EFR gauge.
Accordingly, t h e takeoff was aborted. The crew then noted t h e l o s s of
a l l three generators. The No. 2 generator was showing a d i f f e r e n t i a l
f a u l t , while No. 1 and No. 3 generators indicated an overvoltage condition.
It was l a t e r found t h a t t h e No. 2 generator control panel had a
f a u l t y SCR 15/ i n t h e d i f f e r e n t i a l control c i r c u i t ; a f t e r being heated f o r
about 45 minutes, it would cause a standing d i f f e r e n t i a l f a u l t t o e x i s t
which could not be r e s e t . The No. 1 voltage regulator was found t o
modulate a t about 25 v o l t s peak-to-peak, a t about 20 cycles per second,
due t o an intermittent open c i r c u i t i n t h e conductor L-1 i n t h e voltage
regulator it s e l f .
The t h i r d incident occurred at San Francisco on J u l y 18, 1969.
After t h e a i r c r a f t turned o f f t h e runway, e s s e n t i a l power was switched
from No. 3 generator t o No. 1, t h e No. 1 b u s t i e breaker then t r i p p e d on
overexcitation and t h e No. 1 generator breaker was tripped manually. All
generator power was l o s t . Essential power was switched t o standby and
normal power restored.
UAL -was unable t o duplicate t h e above circumstances, e i t h e r on t h e
ground o r i n f l i g h t t e s t s . The generator control panels were removed
from t h e a i r c r a f t and functionally tested. The incident i s still under
investigation.
&gine pressure r a t i o .
Silicone controlled r e c t i f i e r
.
2.
2.1
ANALYSIS AHD CONCLUSIONS
Analysis
On t h e b a s i s of t h e evidence adduced from t h e wreckage, and t h e
recorded crew conversation i n t h e f i n a l moments of f l i g h t , it i s apparent t h a t t h e a i r c r a f t was i n an abnormal a t t i t u d e when it struck
t h e water. The l i n d t e d s c a t t e r of t h e wreckage i s indicative of a steep
impact angle, while t h e fragmentation p a t t e r n indicates t h a t t h e a i r c r a f t
impacted a t a r e l a t i v e l y high r a t e of speed i n a r i g h t wing low, nose low
a t t i t u d e . The exclamations of t h e f i r s t o f f i c e r during t h e f i n a l seconds
("Keep it going up
you're a thousand f e e t
p u l l it up") f u r t h e r demons t r a t e t h a t l o s s of a t t i t u d e o r i e n t a t i o n was experienced p r i o r t o s t r i k i n g
t h e water.
-
-
Based upon t h e f a c t t h a t p a r t s of a l l major elements of t h e a i r c r a f t were e i t h e r recovered o r were i d e n t i f i e d by means of t e l e v i s i o n ,
coupled with t h e f a c t t h a t these p a r t s were a l l located within a relat i v e l y small area on t h e ocean bottom, it can be concluded t h a t t h e a i r c r a f t w a s e s s e n t i a l l y i n t a c t a t impact. The extensive fragmentation of
t h e wreckage precluded any determination concerning t h e condition of t h e
control system at Impact. However, t h e r e was enough evidence t o conclude
t h a t t h e No. 2 and No. 3 engines were capable of producing a s u f f i c i e n t
l e v e l of power t o sustain t h e a i r c r a f t i n f l i g h t , despite t h e f a c t t h a t
t h e No. 1 engine w a s shut down.
I n attempting t o determine t h e f a c t o r s underlying t h e l o s s of attitude reference t h e t h r u s t of t h e investigation was primarily focused on
two areas: (1) The circumstances surrounding t h e f i r e warning on t h e
No. 1 engine, and (2) The nature of t h e e l e c t r i c a l power problems experienced during t h e f l i g h t , including t h e i r e f f e c t on t h e c a p a b i l i t y
of t h e crew t o f l y t h e a i r c r a f t .
With respect t o t h e first of these two areas, t h e r e was no evidence of f i r e on any part of t h e recovered wreckage, including t h e No. 1
engine and adjacent structure. It i s d i f f i c u l t t o reconcile t h i s lack
of physical evidence of f i r e with ground witness observations of f i r e o r
sparks i n f l i g h t . It i s possible, however, t h a t a phenomenon did i n f a c t
occur which provided ground witnesses with a view of flames o r t h e appearance of sparks. One such p o s s i b i l i t y would be a t r a n s i e n t compressor
stall on one of t h e two operating engines a f t e r t h e a i r c r a f t assumed an
unusual f l i g h t a t t i t u d e p r i o r t o impact. One other p o s s i b i l i t y , although
remote, i s a t r a n s i e n t compressor o r turbine rub o r t h e ingestion of a
small p a r t i c l e by one of t h e two operating engines, which could r e s u l t i n
t h e emission of sparks. Such an occurrence would not necessarily i m p a i r
t h e operation of t h e engine, nor would evidence of it necessarily be
detectable a f t e r impact and t h e r e s u l t a n t massive deformation of engine
r o t a t i n g component s
.
To t h e extent t h a t t h e s e two sources of evidence a r e deemed incons i s t e n t , t h e Board i s of t h e view t h a t physical evidence, o r l a c k thereof,
i s more persuasive than t h e observations o f several witnesses on a dark,
rainy night. It i s t h e r e f o r e concluded t h a t an i n - f l i g h t engine f i r e did
not occur.
The remaining possible causes of t h e f i r e warning, once an a c t u a l
f i r e i s discounted, a r e an overheat o r a f a l s e warning. The physical
evidence derived from t h e wreckage, although negative i n regard t o both
of t h e s e p o s s i b i l i t i e s , cannot be considered d e f i n i t i v e . Accordingly,
no conclusive reason f o r t h e f i r e warning could be established.
Based s o l e l y on t h e past h i s t o r y of f i r e warnings on t h e subject
type of engine, t h e most probable cause of t h e f i r e warning was a n overheat condition within t h e engine compartment, which i n t u r n probably
r e s u l t e d from a duct leak. Even i f such an assumption were t o be made,
25O F. sensor was
however, we do not believe t h e f a c t t h a t a 325O
incorporated on t h e No. 1 engine, r a t h e r than a '375O
25' F. sensor,
can be considered a causal f a c t o r i n regard t o t h e f i r e warning. The
incorporation of t h e higher temperature sensor w a s not mandatory.
Furthermore, t h e higher temperature sensor merely delays t h e a c t i v a t i o n
of t h e f i r e warning, it does not reduce t h e number of warnings. It
therefore appears t h a t while a 375' sensor would not have been t r i g g e r e d
at t h e same p r e c i s e point i n time as t h e 325' u n i t , it would have been
actuated eventually, again assuming that some duct leakage did, i n f a c t ,
exist.
/
/
I n any event, t h e No. 1 engine f i r e warning and shutdown, and t h e
r e s u l t a n t reduction of a v a i l a b l e generators t o one, should not alone
have caused t h e subsequent l o s s of a t t i t u d e o r i e n t a t i o n and crash of t h e
a i r c r a f t , inasmuch a s t h e a i r c r a f t should have been operable with only
one generator or, indeed, with none a t all. In other words, t h e crew
should have been a b l e t o land t h e a i r c r a f t s a f e l y i f t h e r e had been no
problems o t h e r t h a n ' t h e l o s s of t h e No. 1 engine.
A s t h e i n v e s t i g a t i o n progressed, it became increasingly apparent
t h a t t h e e l e c t r i c a l power problems encountered by F l i g h t 266 were most
d i r e c t l y responsible f o r t h e eventual l o s s of orientation. I n order t o
f a c i l i t a t e an analysis of t h e cause, nature, and e f f e c t of t h e s e problems,
a chronological discussion of t h e pertinent events which occurred on
Flight 266 i s s e t f o r t h below.
The CTE shows t h a t t h e crew on F l i g h t 266 was aware t h a t t h e No. 3
generator was i n o p e r a t i v e p r i o r t o departure. It can t h e r e f o r e reasona b l y be assumed t h a t t h e second o f f i c e r t u r n e d o f f t h e g a l l e y power
switch and one of t h e two air conditioning packs p r i o r t o t a k e o f f , a s
prescribed by UAL procedures. Based on t h e cockpit voice recorder and
t h e f l i g h t d a t a recorder, t h e t a k e o f f and e a r l y portion of t h e climbout
were normal. The only i n d i c a t i o n of anything unusual during t h i s period
was t h e observation o f one ground witness t h a t sparks were emanating
from t h e r e a r engine and r i g h t s i d e of t h e a i r c r a f t . As noted previously,
one possible explanation f o r t h e r e p o r t e d sparks would be a t r a n s i e n t compressor o r t u r b i n e rub o r t h e i n g e s t i o n of a small p a r t i c l e i n t o t h e engine.
It i s a l s o p o s s i b l e t h a t t h e sparks were an e a r l y manifestation of t h e
e l e c t r i c a l problem which l a t e r w a s t o cause t h e l o s s of a l l generator power.
The above explanations a r e no more t h a n p o s s i b i l i t i e s , however, inasmuch a s
t h e a v a i l a b l e evidence does not permit a conclusive determination concerni n g t h e sparks.
A t 1.818:30, t h e sound of a warning b e l l was heard i n t h e cockpit.
Four seconds l a t e r , t h e f i r s t o f f i c e r i d e n t i f i e d t h e b e l l as t h e "number
one f i r e warning," and s h o r t l y t h e r e a f t e r t h e recorded conversation
i n d i c a t e s t h a t he p u l l e d back t h e t h r u s t l e v e r on t h e No. 1 engine, as
prescribed by-the engine f i r e emergency procedures. A t 1818:lA, a second
warning horn was heard, which undoubtedly w a s t h e r e s u l t of t h e landing
gear warning switch being a c t i v a t e d a s , t h e t h r u s t l e v e r was r e t a r d e d with
t h e landing gear i n t h e up and locked p o s i t i o n .
Commencing at 1818:45, t h e f i r s t o f f i c e r s t a t e d twice t h a t t h e airc r a f t w a s now on one generator. The c a p t a i n responded by s t a t i n g "Yeah,
It i s t h e r e f o r e apparent t h a t t h e crew
watch t h a t e l e c t r i c a l loading."
was c l e a r l y aware of t h e l i m i t a t i o n s imposed by t h e reduction i n availa b l e e l e c t r i c a l power. A t 1818: 52, t h e f i r s t o f f i c e r posed t h e question
"Everything o f f ? " which could have been d i r e c t e d t o t h e second o f f i c e r as
a followup t o t h e preceding remark by t h e c a p t a i n t o assure t h a t a l l unnecessary e l e c t r i c a l l y powered components were turned o f f . The f i r s t
o f f i c e r ' s i n q u i r y w a s apparently s a t i s f i e d , s i n c e t h e r e w a s no f u r t h e r
conversation on t h e s u b j e c t .
A t 1819:05, t h e first o f f i c e r reported t o Departure Control t h e
predicament of t h e f l i g h t along w i t h t h e crew's i n t e n t i o n t o r e t u r n .
A t 1819:13.5, 5 seconds a f t e r t h e end of t h e transmission t o Departure
Control, CVR operation ceased. F l i g h t recorder operation terminated
simultaneously. I n a d d i t i o n , t h e departure c o n t r o l l e r s t a t e d t h a t t h e
transponder t a r g e t of t h e a i r c r a f t disappeared o f f t h e radarscope at
approximately t h i s same point i n time. It can t h e r e f o r e b e concluded
t h a t t h e a i r c r a f t l o s t i t s only o p e r a t i n g generator (No. 2) at 1819:13.5.
The preceding analysis of t h e events leading up t o and including l o s s
of e l e c t r i c a l power i s based p r h a r i l y on t h e cockpit voice recorder.
Although t h e CVR provides no indications as t o t h e second o f f i c e r ' s actions
during t h i s period, several deductions i n t h i s regard can be made. A t t h e
time of t h e f i r e warnin , t h e e s s e n t i a l power s e l e c t o r switch was probably
on t h e No. 1 engine. 167 The second o f f i c e r ' s f i r s t step, as prescribed by
t h e emergency procedures, would have been t o move t h i s switch from t h e No. 1
engine t o t h e No. 2 engine. That he i n f a c t accomplishedthis s t e p p r i o r t o
t h e shutdown of t h e No. 1 engine i s shown by t h e f a c t t h a t t h e CVR, which i s
connected t o t h e e s s e n t i a l bus, remained operating a f t e r t h e No. 1 engine
was shut down.
The No. 1 engine would have been shut down by t h e pulling of t h e f i r e
switch, which probably occurred not l a t e r than-the time (l818:52) when t h e
f i r s t o f f i c e r posed t h e question "Everything off?" The pulling of t h i s
switch energizes a time delay c i r c u i t t h a t i n t u r n t r i p s t h e generator
f i e l d relay and t h e generator breaker within 5 t o 9 seconds. Accordingly,
by 1819:01 at t h e l a t e s t , t h e No. 2 generator would have been carrying not
only t h e e s s e n t i a l bus load, but a l s o t h e loads of all t h r e e buses, since
it can be assumed t h a t a l l t h r e e bus t i e breakers were s t i l l closed. A t
1819:13.5, t h e No. 2 generator tripped o f f t h e l i n e , leaving t h e a i r c r a f t
with no generator power.
The dearth of physical evidence makes it d i f f i c u l t t o explain t h e l o s s
of t h e No. 2 generator at t h i s point i n time. It i s not possible t o
determine from t h e CVR whether normal e l e c t r i c a l power (115 v o l t s ) was
being developed at t h e time power was l o s t . Although t h e l e v e l of power
indicated on t h e CVR was apparently normal, voltage drops of 30 t o 40 v o l t s
a r e not detectable on t h e CVR. If it i s assumed t h a t t h e power l e v e l was
normal, any of t h e various f a u l t detection c i r c u i t s could have operated t o
t r i p t h e No. 2 generator.
I n any event, it i s apparent t h a t t h e placement of t h e e l e c t r i c a l
load of aJ.l t h r e e generator buses plus t h e e s s e n t i a l bus on t h e No. 2
generator was instrumental i n t r i p p i n g t h a t generator o f f t h e l i n e .
I f t h e l i n e voltage dropped abruptly from normal t o zero, one possible
cause could have been a d i f f e r e n t i a l f a u l t . I f t h e problem were a
161
-
This switch i s normally selected t o t h e operating generator which has
t h e l e a s t amount of e l e c t r i c a l load on i t s bus. Of t h e t h r e e generators,
No. 3 has t h e smallest bus load, No. 1 t h e next l a r g e s t load, and No. 2
t h e l a r g e s t . Since No. 3 generator had been rendered inoperative, No. 1
would have been selected.
differential fault,
it might not have created t h e 30 t o b.0 amperes
d i f f e r e n t i a l required t o a c t i v a t e t h e d i f f e r e n t i a l protection c i r c u i t r y ,
u n t i l t h e l o s s of t h e No. 1 generator placed t h e f u l l e l e c t r i c a l load
on t h e No. 2 generator.
Another possible cause of t h e No. 2 generator's t r i p p i n g o f f t h e
l i n e could have been an overload o r under voltage condition. Such a
condition could have resulted from appropriate reductions i n t h e
e l e c t r i c a l load not being accomplished subsequent t o t h e l o s s of t h e
No. 1 generator. Single generator procedures prescribe that t h e g a l l e y
power switch and both air conditioning pack switches should be turned
OFF. One of t h e pack fans and t h e galley power switch should already
have been i n t h e OFF position a t t h e time t h e No. 1 generator was l o s t
since t h e f l a p s had not yet been retracted, 181 leaving only t h e remaining pack f a n switch t o be turned o f f t o r e a c h t h e prescribed load l e v e l .
Accordingly, it i s d i f f i c u l t t o believe t h a t crew mismanagement of t h e
e l e c t r i c a l system produced an overload condition. However, i f any one
of the various components turned o f f were not i n f a c t disengaged from
t h e e l e c t r i c a l power source, an overload could r e s u l t . Even i f t h e
e l e c t r i c a l load had been reduced t o t h e proper l e v e l , it i s possible
t h a t a n overload condition r e s u l t e d from t h e remaining generator
supplying a lower than normal amount of voltage.
I f an overload condition did i n f a c t occur, t h e s e v e r i t y of t h e
condition a s well as t h e manner i n which it was imposed may have been
significant. Extensive ground and f l i g h t t e s t i n g conducted a f t e r t h e
accident indicated t h a t during c e r t a i n extreme overload conditions,
s u f f i c i e n t induced interference may be present on some B-727 a i r c r a f t
t o i n h i b i t proper operation of t h e No. 2 time delay c i r c u i t of t h e prot e c t i o n panel. The expected a c t i o n of t h i s panel during such an overload
would be t o t r i p t h e bus t i e breaker (BTB), thereby i s o l a t i n g t h e generator
and i t s load bus from t h e r e s t of t h e system, which usually c l e a r s t h e
overload. However, i f t h e No. 2 time delay c i r c u i t i s disabled by t h e
induced interference, t h e No. 1 time delay c i r c u i t w i l l continue t o sense
t h e overload and, a f t e r 5 t o 9 seconds, w i l l t r i p t h e generator control
r e l a y and t h e generator c i r c u i t breaker, thus removing t h e generator from
A d i f f e r e n t i a l f a u l t e x i s t s when t h e r e i s a difference of a c e r t a i n
preset
anaunt l i n e current between t h e current transformers connected
on t h e n e u t r a l side of t h e generator and those connected on t h e l i n e
side.
181
-
Immediately p r i o r t o t h e sound of t h e f i r e warning b e l l , t h e crew
conversation indicates t h a t t h e first o f f i c e r moved t h e f l a p handle
f r o m t h e 5' t o t h e 2
' position.
t h e system. Applying t h i s theory t o Flight 266, it i s possible t h a t
t h e sudden s h i f t of t h e e n t i r e e l e c t r i c a l load t o t h e No. 2 generator
produced a shock load of s u f f i c i e n t dimensions t o t r i g g e r t h e sequence
described above. 19/
-
It i s remotely possible t h a t t h e apparently uncorrected problem
which existed i n t h e No. 3 generator system may have been a f a c t o r i n
the l o s s of t h e No. 2 generator. The No. 3 system was r e l a t i v e l y f r e e
of problems u n t i l t h e i n s t a l l a t i o n on January 13, 1969, of control panel
S/N 163, which had an extensive history of malfunctions f o r a v a r i e t y of
reasons.
Shortly t h e r e a f t e r , t h e No. 3 generator w a s replaced because
t h e f i e l d relay would not s t a y closed. Three and a half hours l a t e r a
similar discrepancy occurred, a f t e r which t h e No* 3 generator w a s rendered
inoperative. The occurrence of two similar problems within such a short
time a f t e r i n s t a l l a t i o n of a control panel, coupled with t h e f a c t t h a t t h e
generator which was removed functioned properly i n shop t e s t s , i n d i c a t e s
t h a t t h e problem was not corrected and probably was associated with t h e
control panel. A t t h e same time, however, it i s unlikely t h a t t h i s
problem could have affected t h e No. 2 generator system since t h e No. 3
system should have been e f f e c t i v e l y i s o l a t e d when it w a s rendered inoperative 3 days p r i o r t o t h e accident, assuming that t h e relays involved
i n i s o l a t i n g t h e No. 3 system c i r c u i t r y functioned properly.
SO/
Regardless of t h e cause of t h e No. 2 generator's t r i p p i n g off t h e
l i n e , t h e l o s s of all generator power should not i n i t s e l f have r e s u l t e d
i n l o s s of a l l e l e c t r i c a l power. The a i r c r a f t i s equipped with a standby
system, completely separate from t h e normal system powered by t h e genera t o r s , which supplies power from t h e b a t t e r y t o those instruments and
radios necessary t o allow t h e c a p t a i n ' t o make a safe approach and landing
under instrument conditions. The standby system i s activated, i f t h e
b a t t e r y switch i s on, by placing t h e e s s e n t i a l power s e l e c t o r switch i n
t h e standby position.
There i s evidence, however, t h a t t h e standby system was not i n
operation during t h e period subsequent t o l o s s of t h e No. 2 generator and
p r i o r t o t h e b r i e f r e s t o r a t i o n of e l e c t r i c a l power a t an indeterminate
l a t e r time. If t h e standby system had been activated, t h e crew would
-
191
-
a
A s discussed, hereinafter, t h e b a t t e r y switch may have been inadvertently
turned off p r i o r t o l o s s of t h e No. 2 generator. Flight t e s t s showed
that t h i s too could a f f e c t t h e normal sequence of t h e t r i p p i n g of t h e
various breakers.
These problems may have been caused by t h e f a c t that Westinghouse
Service Bulletin 66-103 (~eptember1966), which recommended t h e
replacement of a s i l i c o n e controlled r e c t i f i e r i n order t o prevent
nuisance t r i p p i n g of t h e d i f f e r e n t i a l protection c i r c u i t r y , had not
been accomplished on panel S/N 163. This replacement had been accomplished on t h e panels i n s t a l l e d i n t h e Nos. 1 and 2 generating
systems on IT7434U.
have had available t h e No. 1 VHF transmitter and receiver and, therefore,
wouldhave been able t o communicate with Departure Control. The f l i g h t ,
however, not only f a i l e d t o respond t o Departure Controlts repeated c a l l s ,
but a l s o reacted t o t h e heading instruction of 060' by turning i n t h e
opposite direction. It thus appears t h a t t h e VHF communications system
and, by t h e same token, t h e standby system were not functioning. Furthermore, i f t h e standby system had i n f a c t been a c t i v a t e d and had operated
properly, t h e r e would have been no reason t o switch the e s s e n t i a l power
back t o t h e No. 2 generator, which was t h e s e t t i n g when power was restored
and t h e a i r c r a f t apparently went out of control. In view of t h e foregoing,
t h e Board concludes t h a t t h e standby system was not activated o r f a i l e d t o
function.
I n regard t o t h e f a c t t h a t t h e a i r c r a f t was flown on a s t r a i g h t course
a f t e r losing t h e No. 2 generator, without having reference t o a t t i t u d e
instruments, it should be noted t h a t t h e captain would have had adequate
time between t h e f i r e warning and t h e l o s s of t h e No. 2 generator t o l e v e l
the a i r c r a f t and t r i m it up f o r two-engine f l i g h t . Unless he had consciously
attempted t o change heading, t h e trimmed condition would have kept t h e airc r a f t on a r e l a t i v e l y s t r a i g h t course, at l e a s t f o r t h e b r i e f period of
time involved. Moreover, when t h e a i r c r a f t l o s t power and t h e cockpit
became darkened, the captain may have had some outside reference, even i f
only t o a cloud layer.
Although t h e available evidence does not permit a conclusive determination as t o why t h e standby system was not activated o r why it f a i l e d t o
function, one l o g i c a l explanation therefor involves t h e r e l a t i v e positions
of t h e b a t t e r y and galley power switches. N'7434U was a QC model a i r c r a f t ,
and due t o t h e requirements f o r i n s t a l l a t i o n of a cargo smoke detector,
the b a t t e r y panel had been moved and t h e b a t t e r y switch relocated just
above and s l i g h t l y t o t h e l e f t of t h e galley power switch. Both a r e ON-OFF
toggle switches. When t h e No. 1 generator w a s shirt down, one of t h e f i r s t
actions of t h e second o f f i c e r would have'been t o reduce t h e e l e c t r i c a l
load. One of t h e c ~ p o n e n t swhich should be off when operating on one genera t o r i s t h e galley power. Accordingly, even though galley power should
have been o f f since p r i o r t o takeoff, t h e second o f f i c e r may have ins t i n c t i v e l y brushed t h e galley power switch with h i s hand t o make c e r t a i n
it was off and h i t t h e b a t t e r y switch instead. I f t h e b a t t e r y switch had
been inadvertently turned off i n t h e above manner, t h e r e would have been
no indication of i t s being o f f i n t h e cockpit at t h a t time. Thereafter,
when the' No. 2 generator was l o s t , an attempt t o a c t i v a t e t h e standby system
would have been unavailing with t h e b a t t e r y turned off.
I f t h e b a t t e r y switch had not been turned off, there a r e several other
possible explanations why t h e standby system was not activated. The f i r s t
involves t h e UAL emergency procedures f o r l o s s of all generators. A s
constituted a t t h e time of t h e accident, these procedures included no
mention of switching t o standby, but r a t h e r prescribed t h a t any generator
f i e l d relay should be closed and t h e e s s e n t i a l power s e l e c t o r placed on
t h e operating generator. It i s therefore possible t h a t , following l o s s
of t h e No. 2 generator, t h e first o f f i c e r , e i t h e r d i r e c t l y r e f e r r i n g t o
t h e checklist o r with it i n mind, repeatedly attempted t o b r i n g t h e No. 2
generator back on t h e l i n e . On t h e other hand, a U&L i n s t r u c t o r t r a i n e d
t h e second o f f i c e r t o r e s t o r e generator power only once before switching t o
standby. Furthermore, i f t h e second o f f i c e r had not attempted t o switch t o
standby reasonably soon a f t e r t h e No. 2 generator was l o s t , e i t h e r t h e
captain o r t h e first o f f i c e r probably would have reminded him t o do so. %/
A second possible reason t h a t t h e standby system was not activated, if
the b a t t e r y switch was on, involves t h e e s s e n t i a l power s e l e c t o r switch
i t s e l f . This switch must pass through a gate i n order t o be moved i n t o t h e
detented standby position.
Although t h e second o f f i c e r should have been
familiar with t h i s c h a r a c t e r i s t i c of t h e switch, it i s possible that when t h e
cockpit became suddenly and unexpectedly darkened upon l o s s of t h e No. 2
generator, he moved t h i s switch counterclockwise u n t i l he encountered t h e
obstruction and assumed it was i n t h e standby position. I n f a c t , it would
have then been i n t h e APU position, which i s a dead c i r c u i t i n f l i g h t .
It i s a l s o possible t h a t t h e standby system f a i l e d t o function because of a malfunction i n t h e b a t t e r y o r b a t t e r y charger. This could
a l s o explain why t h e crew eventually switchedthe e s s e n t i a l power switch
from standby back t o t h e No. 2 generator, even though t h a t generator was
supplying low voltage. A b a t t e r y malfunction could a l s o c o n s t i t u t e a
d i f f e r e n t i a l f a u l t which might have been t h e cause of t h e No. 2 generator
i n i t i a l l y t r i p p i n g off t h e l i n e .
When all generator power was l o s t , and assuming t h e standby system
was not activated o r f a i l e d t o function, t h e only l i g h t i n g available,
apart from t h a t which might have been provided by f l a s h l i g h t s , would
have been t h e emergency e x i t l i g h t s over t h e door leading t o t h e passenger
compartment. 23/ If t h a t happened, it can be assumed t h a t t h e second
o f f i c e r was attempting e i t h e r t o a c t i v a t e t h e standby system o r t o bring
t h e No. 2 generator back on t h e l i n e , while t h e p i l o t s were doing t h e i r
best t o control t h e a i r c r a f t i n a semi-darkened cockpit with no a t t i t u d e
J
l
2
I n t h i s connection, it should be noted that a red l i g h t on t h e second
o f f i c e r ' s instrument p e l becanes illuminated when e s s e n t i a l power i s
l o s t . This l i g h t w i l l remain on a f t e r t h e e s s e n t i a l power s e l e c t o r
switch i s moved t o standby, assuming that t h e b a t t e r y switch i s on,
and thus does not c o n s t i t u t e an indication t h a t t h e standby system
i s not operating.
22/
-
The purpose of t h e detent i s apparently t o assure t h a t t h e operator
i s aware t h a t he i s switching t o an emergency operation.
231
-
These l i g h t s a r e powered by a separate b a t t e r y and a r e activated
automatically when e l e c t r i c a l power i s l o s t .
instruments. If t h e b a t t e r y switch were o f f , thus making it impossible
t o a c t i v a t e t h e standby system, it i s d i f f i c u l t t o comprehend why one
of t h e crewnembers did not t h i n k of t h i s p o s s i b i l i t y and check t h e switch.
The only explanation i s t h a t t h e cockpit was i n a s t a t e of confusion and
each of t h e crew was b u s i l y engaged with h i s own immediate problems, with
t h e consequence t h a t a switch such as t h e battery, which i s presumed t o be
on at all time, was overlooked.
a
A s r e f l e c t e d by t h e reactivation of t h e f l i g h t data recorder and t h e
cockpit voice recorder f o r 15 and 9 seconds,respectively, t h e No. 2
generator came back on t h e l i n e at some l a t e r indeterminate time. Although
t h e precise point i n time when t h e two recorders became reactivated, o r
whether they were reactivated simultaneously cannot be determined, some
rough approximations i n t h i s regard can be made. The radar c o n t r o l l e r
who was handling Flight 266 estimated t h a t t h e primary t a r g e t of t h e a i r c r a f t disappeared from t h e radarscope within two sweeps, o r 5 t o 11
seconds, a f t e r he directed t h e f l i g h t t o t u r n r i g h t t o 060'.
The cont r o l l e r made two successive transmissions containing t h i s heading direction,
t h e f i r s t of which ended at 1820:33, while t h e second terminated a t 1820:U.
Primary t a r g e t disappearance, based on f l i g h t t e s t s , should have occurred
as t h e a i r c r a f t was descending through TOO f e e t and thus can be c l o s e l y
r e l a t e d t o t h e f i n a l remarks a t t h e end of t h e CVR. Three seconds p r i o r
t o CVR termination, t h e f i r s t o f f i c e r s a i d t o t h e captain "Keep it going
up Arnie, you're a thousand f e e t " and 2 seconds l a t e r said, "Pull it up."
It therefore appears t h a t t h e CVR ceased operating a t about t h e same time
t h e primary t a r g e t disappeared.
I n view of t h e absence on t h e CVR of
t h e Departure Control transmissions at 1820:30 t o 1820:33 and 1820:kO t o
1820:44, it can be f u r t h e r approximated t h a t t h e CVR terminated 10 o r 11
seconds a f t e r completion of t h e second of these transmissions and had
resumed operation at 1820: 45 o r 1820: 46.
a
The approximate time when t h e f l i g h t data recorder ceased operation
following t h e reactivation period of 1 5 seconds can be deduced only i f
t h e f i n a l t r a c e indications can be considered reasonably valid. Thus, i f
t h e f i n a l a l t i t u d e t r a c e of 630 f e e t i s accepted a s a reasonably accurate
r e f l e c t i o n of t h e a i r c r a f t a l t i t u d e at t h a t point, it could be concluded
t h a t both recorders ceased operation at t h e same time. It would then
follow t h a t t h e f l i g h t recorder resumed operation 6 seconds p r i o r t o t h e CVR.
"241
-
The only indication t h a t t h e b a t t e r y switch was not on, apart from t h e
i n a b i l i t y t o a c t i v a t e t h e standby system, would have been t h e absence
of c e r t a i n l i g h t s i n t h e cockpit. Under t h e circumstances, however,
t h e i r absence might not be recognized.
The conclusion that t h e CVR terminated p r i o r t o impact, while t h e airc r a f t was s t i l l airborne, i s substantiated by t h e absence of impact
sounds on t h e recording.
The reasons underlying r e s t o r a t i o n of t h e No. 2 generator a r e diffic u l t t o assess, again due t o t h e lack of physical evidence. The f a c t t h a t
components powered by t h e e s s e n t i a l bus (CVB) t h e No. 2 bus ( f l i g h t recorder), and t h e No. 1bus ( a i r data computer) 26/ indicates t h a t t h e No. 2
f i e l d relay, c i r c u i t breaker, and bus t i e breaker were a l l closed and t h a t
t h e e s s e n t i a l power s e l e c t o r switch was positioned t o t h e No. 2 generator.
I n t h i s connection, t h e remark by one of t h e crew, following r e s t o r a t i o n of
power, t h a t t h e " f i e l d ' s o u t " undoubtedly was a reference t o t h e f i e l d r e l a y
l i g h t being off, as it should have been since t h e generator was operating.
a
Tests based on t h e power l e v e l r e f l e c t e d by t h e CVR showed t h a t a low
voltage condition of approximately 50 v o l t s (as opposed t o normal voltage
of 115 v o l t s ) existed when power was restored on Flight 266. This power
l e v e l was simulated by s t a r t i n g one generator with normal a i r c r a f t loading
f o r two generators applied. If t h e problem which caused t h e No. 2 generator
t o t r i p off t h e l i n e s t i l l existed, it i s possible t h a t t h e second o f f i c e r
on Flight 266, i n a last desperate attempt t o r e s t o r e power, manually closed
t h e No. 2 f i e l d r e l a y and held it closed t o keep t h e protection c i r c u i t r y
from t r i p p i n g it. Seconds l a t e r , as t h e a i r c r a f t entered an abnormal
a t t i t u d e , t h e second o f f i c e r ' s hand may have been thrown away from t h e panel,
thus causing the'complete l o s s of t h e remaining generator power available.
It i s a l s o possible t h a t power was restored as a r e s u l t of t h e clearing
of t h e d i f f e r e n t i a l f a u l t , i f one caused t h e i n i t i a l l o s s of No. 2 generator.
I f t h i s happened, t h e low voltage condition should have activated t h e prot e c t i v e c i r c u i t r y which, i n turn, would have t r i p p e d t h e bus t i e breaker and
t h e generator breaker. However, if t h e b a t t e r y switch were s t i l l o f f , t h e
sequence and t h i n g of t h e t r i p p i n g of these breakers would again have been
disrupted. 281
-
The f a c t t h a t t h e two recorders operated f o r e f f e r e n t lengths of time
i s d i f f i c u l t t o r a t i o n a l i z e . The most plausible explanation i s t h a t these
u n i t s require d i f f e r e n t l e v e l s of voltage f o r t h e i r operation and, therefore,
a s t h e voltage output of t h e No. 2 generator b u i l t up and then receded, t h e
CVR e i t h e r became activated l a t e r , o r deactivated sooner, than t h e f l i g h t
recorder.
261
-
The f l i g h t recorder t r a c e s would have been s t r a i g h t horizontal l i n e s
i f power t o t h e a i r data computer had not a l s o been restored.
a
The transponder did not come back on because it has an &second
protective time delay c i r c u i t .
28/
The time delay c i r c u i t r y , if functioning properly, should have tripped
t h e generator o f f t h e l i n e 5 t o 9 seconds a f t e r power was restored a t
an undervoltage l e v e l . Based on t h e f l i g h t recorder, however, some
generator power was available f o r 1 5 seconds.
Regardless of t h e reasons underlying r e s t o r a t i o n of power, it appears
that t h e second o f f i c e r was aware t h a t t h e predicament of t h e f l i g h t was
not yet remedied. This conclusion i s based on h i s remark, several seconds
a f t e r power was restored, t h a t "We're gonna get screwed up," followed by
"I don't know (what's going on)
."
The remaining question concerns t h e causal r e l a t i o n s h i p between t h e
e l e c t r i c a l system problems discussed above and t h e eventual crash. F l i g h t
t e s t s indicated that e l e c t r i c a l power outages would not have a s u b s t a n t i a l
impact on t h e f l i g h t control system. It therefore appears t h a t t h e most
s i g n i f i c a n t adverse e f f e c t of t h e e l e c t r i c a l power l o s s on t h e c a p a b i l i t y
of t h e p i l o t s t o f l y t h e a i r c r a f t would have involved t h e a t t i t u d e reference
instruments, which a r e so c r i t i c a l t o t h e operation of an a i r c r a f t under
instrument conditions.
The b a s i c instrument i n t h e cockpit from which a p i l o t i n a B-727
derives a t t i t u d e information i s t h e a t t i t u d e indicator, which i n t u r n
receives data from an e l e c t r i c a l l y powered v e r t i c a l gyro. When MT434U was
i n i t i a l l y s t a r t e d up, t h i s v e r t i c a l gyro would have established a v e r t i c a l
plane with reference t o t h e ground. When e l e c t r i c a l power was l o s t i n
f l i g h t , a f l a g l a b e l l e d "gyro" would have appeared i n t h e lower f a c e of
t h e a t t i t u d e i n d i c a t o r instrument and t h e i n d i c a t o r would have r o l l e d t o
a 90' pitchup a t t i t u d e . 291 The gyro i t s e l f would then have s t a r t e d t o
coast down, although a c e r t a i n amount of s t a b i l i t y would have been retained
i n t h e gyro assembly. However, i f t h e a i r c r a f t a t t i t u d e were a l t e r e d from
t h e l e v e l p o s i t i o n by climbing o r descending, o r banking l e f t o r r i g h t ,
precession of t h e gyro gimbals would have occurred.
Upon r e s t o r a t i o n of power, t h e a t t i t u d e i n d i c a t o r presentation of 90'
pitchup would have r o l l e d back toward t h e a t t i t u d e of t h e v e r t i c a l gyro.
I n addition, t h e v e r t i c a l gyro would have gone i n t o t h e f a s t erection cycle.
However, i f t h e gyro had precessed during t h e period e l e c t r i c a l power was
l o s t , o r i f t h e a i r c r a f t were i n a position other than l e v e l when power was
restored, t h e gyro would not be referenced t o t h e ground, but r a t h e r would
be sensing and erecting toward a f a l s e v e r t i c a l plane. Accordingly, i f t h e
captain had attempted t o change t h e a t t i t u d e of t h e a i r c r a f t toward an
instrument i n d i c a t i o n of l e v e l f l i g h t under t h e above conditions, he would
have been maneuvering t h e a i r c r a f t with reference t o a f a l s e "horizon,"
which would have served t o aggravate f u r t h e r an already serious o r i e n t a t i o n
problem.
a
The only o t h e r instrument i n t h e cockpit which provides a t t i t u d e infornation, t h e t u r n needle, i s controlled by an e l e c t r i c a l s i g n a l and
t h e r e f o r e would a l s o have been rendered inoperative. When t h e e l e c t r i c a l signal t o t h i s instrument was removed, t h e needle would have remaine?
centered, t h u s indicating l e v e l f l i g h t .
The gyro warning f l a g should have remained i n view during t h e b r i e f
period power was restored. 301 Nevertheless, when t h e cockpit l i g h t s
suddenly came on upon r e s t o r a t i o n of power, causing t h e l o s s of whatever
outside reference may have been available, t h e captain might have turned
t o t h e gyro horizon a s a last r e s o r t i n attempting t o e s t a b l i s h t h e a t t i t u d e
of t h e a i r c r a f t . On t h e other hand, t h e i n t e n s i t y of t h e cockpit l i g h t s , i n
view of t h e low voltage conditions, may not have been bright enough t o allow
t h e p i l o t s t o view t h e instruments. I n e i t h e r event, t h e p i l o t s would have
been without a r e l i a b l e a t t i t u d e reference, e i t h e r inside o r outside t h e
a i r c r a f t . 3-/l
The reasons underlying t h e l e f t t u r n commenced by Flight 266 p r i o r
t o disappearing from t h e radarscope cannot be conclusively determined.
The captain may have been attempting t o t u r n back toward t h e a i r p o r t ,
and elected t o do so t o t h e l e f t i n view of h i l l y coastline which l a y
t o t h e north, o r r i g h t , of t h e a i r c r a f t at t h a t time. It i s a l s o possible
t h a t t h e t u r n represented t h e e a r l y stages of disorientation with regard
t o t h e a t t i t u d e of t h e a i r c r a f t . I n any event, once t h e t u r n was i n i t i a t e d ,
t h e d i f f i c u l t y of t h e captain i n determining t h e a t t i t u d e of t h e a i r c r a f t
would have accelerated. This conclusion i s substantiated by t h e remarks of
t h e f i r s t o f f i c e r during t h e f i n a l moments ( " ~ e e pit going up
.I'
"Pull
it up"), which apparently were prompted by h i s concern about t h e rapid l o s s
of a l t i t u d e . Even i f t h e captain had pulled back on t h e yoke i n response
t o those remarks, t h e descent would not have been a r r e s t e d unless t h e wings
were levelled. Without any a t t i t u d e reference, t h e captain may have held
t h e yoke as nearly centered as possible, thus causing t h e l e f t t u r n t o
t i g h t e n a s t h e a i r c r a f t descended t o impact.
..
One f i n a l matter which warrants comment concerns t h e f a c t t h a t t h e
captain on Flight 266 had been f l y i n g only DC-8's since December 2, 1968.
Apparently, t h e r e i s no difference between t h e B-727 and t h e DC-8 i n terms
of cockpit configuration and instrument location t h a t could have s i g n i f i cantly affected t h e captain's reactions under emergency conditions, other
than t h e f a c t t h a t t h e DO-8 has no standby e l e c t r i c a l system. Nevertheless,
t h e r e l a t i v e lack of f a m i l i a r i t y i n i t s e l f , r e s u l t i n g from 7 weekst absence
from t h e a i r c r a f t , nay have posed problems, a l b e i t minor. For example,
t h e f l i g h t controls on t h e DC-8 require g r e a t e r pressure t o move than those
on t h e B-727. That such a difference i s noticeable t o p i l o t s i s demons t r a t e d by t h e captain's comment t o t h e first o f f i c e r , shortly a f t e r takeo f f , "You handle these things l i g h t on t h e controls,'' t o which t h e f i r s t
o f f i c e r responded "Yeah."
30/
311
-
Under t h e low voltage conditions prevailing a f t e r power restoration,
there would have been no power supplied t o t h e f l a g r e t r a c t i o n c i r c u i t r y .
The t u r n needle may a l s o have been affected by t h e deficiency i n t h e
restored power l e v e l .
On balance, t h e r e i s i n s u f f i c i e n t evidence t o support a conclusion
t h a t t h e captain's having flown only DC-8's i n t h e 7 weeks preceding t h e
accident was a contributing f a c t o r . Nevertheless, t h e Board, believes
t h a t t h i s type of scheduling could p o t e n t i a l l y lead t o a compromise i n
safety. Accordingly, we note with approval t h a t United Air Lines has
adopted a procedure whereby p i l o t s who have completed t r a n s i t i o n a l
t r a i n i n g i n a p a r t i c u l a r a i r c r a f t a r e afforded t h e opportunity t o refamiliarize themselves i n another a i r c r a f t , i n which they had previously
been checked out, p r i o r t o being assigned f l i g h t s i n t h e l a t t e r a i r c r a f t
2.2
Conclusions
(a)
Findings
The flightcrew was properly c e r t i f i c a t e d and q u a l i f i e d t o
conduct t h e f l i g h t .
The captain had been t r a n s i t i o n i n g t o t h e DC-8 during t h e
period p r i o r t o t h e accident and had not flown i n a E727
since December 2, 1968.
The a i r c r a f t was properly c e r t i f i c a t e d and airworthy.
The a i r c r a f t had been operating f o r 42 f l i g h t hours p r i o r
t o t h e accident with t h e No. 3 generator inoperative, a s
d o w e d by t h e Minimum Equipnent List.
The discrepancy which caused t h e No. 3 generator t o be
rendered inoperative had not been corrected and probably
was associated with i t s e l e c t r i c a l control panel.
The f l i g h t experienced a f i r e warning on t h e No. 1 engine
during climbout and t h e engine w a s shut down.
There was no physical evidence i n t h e recovered wreckage
indicating t h a t an i n - f l i g h t f i r e had occurred.
Shortly a f t e r shutdown of t h e No. 1 engine, e l e c t r i c a l
power from t h e remaining generator (No. 2) was l o s t .
The available evidence does not permit a determination a s
t o t h e exact cause of t h e l o s s of all generator power,
other than associating t h i s l o s s with t h e sudden placement
of aJ.l t h r e e generator bus loads, a s well as t h e e s s e n t i a l
bus, on t h e No. 2 generator.
Following l o s s of all generator power, t h e standby e l e c t r i c a l
system e i t h e r was not activated o r f a i l e d t o function.
E l e c t r i c a l power a t a voltage l e v e l of approximately 50 v o l t s
was restored approximately a minute and a half a f t e r l o s s of
t h e No. 2 generator.
The duration of power r e s t o r a t i o n was 9 t o 15 seconds,
following which power was again l o s t at some indeterminate
point p r i o r t o impact.
The a i r c r a f t w a s i n an abnormal a t t i t u d e at impact.
The No. 2 and No. 3 engines were developing power at impact.
There was no evidence of a malfunction i n t h e f l i g h t control
system.
The f l i g h t was conducted under night, instrument conditions.
The p i l o t s would have been without a r e l i a b l e a t t i t u d e
reference, e i t h e r inside o r outside t h e a i r c r a f t , from
t h e point i n time t h e No. 2 generator was l o s t u n t i l
impact.
(b)
Probable Cause
The Board determines t h a t t h e probable cause of t h i s accident was
l o s s of a t t i t u d e o r i e n t a t i o n during a night, instrument departure i n which
t h e a t t i t u d e instruments were disabled by l o s s of e l e c t r i c a l power. The
Board has been unable t o determine ( a ) why a U generator power was l o s t o r
( b ) why t h e standby e l e c t r i c a l -power system e i t h e r was not activated o r
f a i l e d t o function.
3.
RECCMMENDA.TIONS AMD COBEECTIVE MEASURES
By l e t t e r dated J u l y 11, 1969, t h e Chairman of t h e Safety Board
recommended t o t h e Administrator of t h e FAA t h a t t h e automatic switching
of e s s e n t i a l power t o standby power upon l o s s of a l l generators be made
a mandatory requirement f o r all turbine-powered a i r c r a f t . It was f u r t h e r
recommended t h a t u n t i l such time as t h e above requirement could be implemented throughout t h e industry, t h e emergency checklists f o r a l l a i r l i n e s
pertaining t o "Loss of a l l Generators" require t h a t t h e second o f f i c e r ,
o r captain i f appropriate, check t o assure t h a t t h e b a t t e r y switch i s ON,
then immediately switch e s s e n t i a l power t o t h e standby o r emergency position.
It was t h e Safety Board's view t h a t t h i s would give t h e captain t h e
instruments and l i g h t s necessary t o f l y t h e a i r c r a f t while t h e second
o f f i c e r could "troubleshoot" t h e e l e c t r i c a l system.
I n h i s response of J u l y 28, 1969, t h e Administrator s t a t e d t h a t t h e
FAA had been investigating e l e c t r i c a l emergency operating procedures f o r
sane time and a c t i o n was being taken t o prescribe procedures f o r t h e B-727
consistent with Safety Board recommendations. 321 With regard t o automatic
switching f o r e s s e n t i a l f l i g h t instruments, t h e ~ d m i n i s t r a t o'rs l e t t e r
referred t o Sections 25.1309 and 25.1333 of Notice of Proposed Rule Making
(HIRM) 68-18, which provide f o r t h e immediate a v a i l a b i l i t y of e s s e n t i a l
instruments a f t e r e l e c t r i c a l f a i l u r e s and which apply t o a i r c r a f t with a
date of application f o r type c e r t i f i c a t i o n a f t e r adoption of t h e proposed
rule. For inservice a i r c r a f t , t h e FAA had issued IiPFZM 69-26 which provides
f o r t h e i n s t a l l a t i o n i n l a r g e turbojet-powered airplanes used i n t h e a i r
c a r r i e r service of a t h i r d independently powered a t t i t u d e indicator. 331
The Administrator expressed t h e b e l i e f t h a t t h i s action, combined w i t h
specified a i r p l a n e f l i g h t manual emergency procedures, w i l l provide f o r
a s a t i s f a c t o r y l e v e l of s a f e t y f o r inservice a i r c r a f t .
I n order t o remove any doubt as t o t h e s t a t u s of t h e standby system
during a "Loss of all Generators" emergency, it i s f u r t h e r recommended t h a t
t h e second o f f i c e r on a B-727 be provided with a positive indication on
321
-
a
The FAA issued an Airworthiness Directive, e f f e c t i v e August 1, 1969,
requiring revision of t h e Boeing 727 Airplane Flight Manual, Bnergency
Procedures Section, Loss of all Generators paragraph, t o include procedures which would d i r e c t t h e flightcrew t o switch t o t h e standby
power system, insure t h e b a t t e r y switch i s "ON", and reduce loads.
The proposal embodied i n NEW 69-26 was adopted on January 8, 1970,
and became e f f e c t i v e on February 5, 1970, a s Section 121.305(j)
of t h e FAR, which requires t h a t t h e additional a t t i t u d e indicator
be i n s t a l l e d on a l l l a r g e turbojet a i r c r a f t a f t e r August 5, 1971.
h i s panel when t h e standby system i s being powered from t h e battery.
Such an indication could take t h e form of a l i g h t , such as t h a t i n s t a l l e d
on t h e B- 747 a i r c r a f t f o r t h e sane purpose. The l i g h t would become illuminated when t h e standby system i s activated. Another a l t e r a t i o n which
might be considered i n connection with t h e foregoing recommendation would
be t h e t r a n s f e r of t h e standby feature from t h e e s s e n t i a l power s e l e c t o r
switch t o a separate OK-OFF toggle switch, which again i s t h e arrangement
on t h e B-747. The addition of such a switch would not only serve t o
simplify a c t i v a t i o n of t h e standby system, but would a l s o f a c i l i t a t e
troubleshooting t h e generators when t h e standby system i s on:
The FAA a l s o took several other actions r e l a t i n g t o t h e subject
accident. A s a r e s u l t of information developed during t h e e a r l y stages
of t h e investigation, t h e FAA issued an Airworthiness Directive by
telegram on January 31, 1969, requiring B-727 operators t o provide a
means t o prevent inadvertent operation of t h e b a t t e r y switch i n those
a i r c r a f t i n which t h e b a t t e r y switch i s located within 10 inches of t h e
galley power switch.
On August 1, 1969, t h e FAA proposed an Airworthiness Directive
requiring t h e i n s t a l l a t i o n of a capacitor i n accordance with b e i n g
Service Bulletin No. 24-47 (March 3, 1969), f o r t h e purpose of f i l t e r i n g
out e l e c t r i c a l interference which may be present t o a s u f f i c i e n t extent
on some B-727 a i r c r a f t t h a t , under an overloaded condition, t h e generator
control panel may disable t h e generator before opening t h e bus t i e c i r c u i t
breaker.
On September 10, 1969, t h e FAA proposed an Airworthiness Directive
which would require replacement of both s i l i c o n controlled switches CR 10
and CR 28 with a t r a n s i s t o r i z e d amplifier and a miniature two-pole r e l a y
on B-727 airplanes, i n accordance with Westinghouse Service W e t i n 103,
dated September 15, 1966. A s a reason f o r t h i s replacement, t h e FAA c i t e d
f a i l u r e s of t h e generator overload protection c i r c u i t s i l i c o n controlled
r e c t i f i e r s , causing a single generator system lockout on B-727 a i r c r a f t .
During t h e investigation, a considerable amount of a t t e n t i o n was
focused on t h e Minimum Equipnent List (MEL) and, more s p e c i f i c a l l y , on
t h e question of whether t h e MEL, with regard t o t h e required number of
operative generators, was adequate i n l i g h t of t h e subject accident.
The MEL f o r t h e B-727 was established through extensive ground and f l i g h t
t e s t i n g , a f t e r which it w a s agreed through meetings with t h e involved
p a r t i e s , including t h e FAA, Boeing, and United, t h a t t h e a i r c r a f t would
be airworthy with two generators. An additional margin of s a f e t y was provided by t h e standby system, through which e l e c t r i c a l power could be
supplied from t h e b a t t e r y t o those instruments and components necessary
t o enable t h e p i l o t t o make an approach and landing under instrument
conditions. The t h i r d generator was included on t h e &-727, not as a
matter of safety, but r a t h e r t o enhance schedule dependability. For
example, i f one of t h e t h r e e generators should become disabled, t h e
a i r c r a f t would s t i l l be able t o operate without delay through small
f i e l d s which lack t h e maintenance capability t o r e p a i r an inoperative
generator.
Subsequent t o c e r t i f i c a t i o n , the B-727 e l e c t r i c a l system has been
a l t e r e d i n minor respects only, which primarily involved changes i n
procedures r a t h e r than increases i n loading. Furthermore, t h e f l i g h t
t e s t s conducted a f t e r t h e accident substantiated t h e a b i l i t y of t h e a i r c r a f t t o carry design loads during one and two generator operation.
FinaUy, and perhaps most i m p r t a n t l y , t h e f a c t t h a t Flight 266 departed
with one generator.inoperative cannot be c l a s s i f i e d as a causal f a c t o r i n
t h e accident. The shutdown of t h e No. 1 engine, t h e l o s s of t h e No. 2
generator, and t h e nonactivation of t h e standby system a r e all unrelated
t o t h e No. 3 generator i n t e r n s of cause.
I n view of t h e foregoing, t h e Board believes there i s no b a s i s upon
which t o recommend t h a t t h e MEL f o r t h e B-727 be revised t o require t h a t all t h r e e generators be operative. A t t h e sane time, we believe t h a t
repairing components beyond those required by t h e MEL, as soon as p r a c t i cable,is consistent with sound maintenance and engineering practices.
Furthermore, it can even be s a i d t h a t maintaining such components i n
operating condition has t h e added e f f e c t of enhancing safety, inasmuch
as it increases t h e available degree of redundancy.
FinaUy, a b r i e f coment i s warranted concerning t h e o v e r a l l e l e c t r i c a l system on t h e B-727. Recommendations have been made and corrective
measures adopted, as described hereinabove, t o correct those discrepancies
and procedures uncovered during t h e investigation which might have
contributed t o the accident. The Board believes t h a t these steps should
go a long way toward preventing t h e occurrence of a similar accident. A t
t h e same time, we recognize that e f f e c t i v e prevention i s l i m i t e d by t h e
f a c t t h a t t h e lack of physical evidence has not allowed a conclusive
determination of why t h e No. 2 generator was l o s t and why t h e standby
system w a s not activated o r f a i l e d t o function. Our concern i n t h i s
instance i s increased by t h e several incidents subsequent t o t h e accident
involving l o s s of all t h r e e generators on B-727 a i r c r a f t . Despite t h e
generally excellent performance history- of t h e B-'727' e l e c t r i c a l system,
t h e p x s i b i l i t y remains, unless and u n t i l t h e reasons u n d e r w n g these
- 33 power l o s s e s a r e determined, that a camon problem within t h e system
i s responsible. Accordingly, t h e Board urges all B-727 operators t o
be p r t i c u l a r l y thorough i n investigating any incidents of a s h i l a r
nature i n order t h a t every possible e f f o r t be made t o uncover t h i s
problem, should one e x i s t .
BY THE NATIONAL TRANS PORTATION SAFETY BOARD :
JOHN H. REED
Chairman
OSCAR M. LAUREL
Member
FRANCIS H. McAEfeMS
Member
LOUIS M.
Member
THAYER
ISABEL A. BURGESS
Member
March 18, 1970
Intentionally Left Blank
in Original Document
Appendix A
INVESTIGATION AND HEARING
1. Investigation
The Board received o f f i c i a l n o t i f i c a t i o n of t h e accident a t approximately 2200 e.s.t., on January 18, 1969. An investigating team was
dispatched from Washington, D. C., several hours t h e r e a f t e r and arrived
i n Los Angeles i n t h e e a r l y morning hours of January 19. Upon a r r i v a l ,
working groups were established f o r Operations, Witnesses, Air T r a f f i c
Control, Human Factors, Weather, Structures, Powerplants, Systems,
Maintenance Records, Cockpit Voice Recorder, and Flight Recorder. P a r t i e s
of I n t e r e s t p a r t i c i p a t i n g i n t h e investigation included t h e Federal
Aviation Administration, United Air Lines, t h e Boeing Company, Air Line
P i l o t s Association, P r a t t & Whitney Division of United Aircraft Corporation, and Professional Air Traffic Controllers Organization. Due t o
t h e d i f f i c u l t i e s involved i n locating and recovering t h e wreckage, t h e
on-scene investigation was not completed u n t i l March 19, 1969.
The on-site i n v e s t i g a t i o n consisted b a s i c a l l y of four phases: ( a )
search f o r t h e wreckage, (b) i d e n t i f i c a t i o n and p l o t t i n g of wreckage, ( c )
recovery of p r i o r i t y items, and (d) recovery of remaining p a r t s of t h e
wreckage. The wreckage w a s located on January 31, 1969, i n approximately
1,000 f e e t of water by a vessel equipped with side-looking sonar
,
The p l o t t i n g and i d e n t i f i c a t i o n of t h e wreckage was acequipnent.
complished by t h i s same vessel u t i l i z i n g "J-Star" equipnent, which has
both t e l e v i s i o n and sonar capability. The t h r e e engines were recovered
on February 11, 1969, with t h e a s s i s t a n c e of t h i s equipnent o u t f i t t e d
with a s p e c i a l clamp. The voice recorder, f l i g h t recorder,. smal1,engine
components and some e l e c t r i c a l parts were recovered during t h e period
February 21, 1969, through March 4, 1969, by a submersible vehicle. The
f i n a l gross recovery phase was c a r r i e d out during t h e period March 6,
1969, through March 19, 1969,by means of a trawler, which involves dragging
a net over t h e ocean f l o o r .
2.
Hearing
A public hearing was held at t h e Miramar Hotel i n Santa Monica,
California, on August 13 t o 15, 1969.
A preliminary aircraf't accident r e ~ r summarizing
t
t h e f a c t s disclosed
by t h e investigation was published by t h e Board on June 9, 1969. A
summary of t h e testimony which was taken at t h e public hearing w a s released
on September 5, 1969.
S a a z (sound navigation ranging) i s an apparatus which transmits highfrequency sound waves i n water and r e g i s t e r s t h e vibrations r e f l e c t e d
back from an object
.
CREW IBFOBMATION
Captain
Leonard A. Leverson
2036 Victoria Drive
Santa Ana, Calif.
First Officer
Walter R. Schlemmer
3131 Old Coach Drive
Camarrillo, Calif.
Second Officer
Keith R. Ostrander
506 Dena Drive
Newbury Bark, Calif.
Certificates
Held :
ATR 470722
Class I Medical
Dated 11/26/68
F/E
Commercial 1582882
1601250
Class 11 1/29/68
F/E(S/O)
Limitations:
None
None
None
Pilot
Eatings :
ASEL & MES &
Instrument
AMEL
Total
Time ( T.T.):
13,665 hours
6642 Pilot, 889 S/O
T. T. in Type:
1,908 hours
1842 Pilot,
T. T. Last 90
78 hours
200 hours
40 hours
T. T. Last 90
Days in Type:
61 hours
200 hours
40 hours
Rest Period 24
Hours Prior to
Accident :
22.6 hours
22.6 hours
Duty Time
Last 24
Hours:
1.4 hours
1.4 hours
1.4 hours
Time This
Flight:
.3 hours
.3 hours
.3 hours
Address :
Age:
Hire kte:
-
-
&
Instrument
Commercial 1711270
1812272
Class 11 9/13/68
-
ASEL
DC-6, B-727
174 Pilot, 460 S/O
543 S/O
Days :
APPENDIX
c
TRANSCFUFTION OF VOICE COMMOHICATIONS RECORDED OH THE LAST 2 MUTOTES
AND 25 SECONDS OF THE CAM AND COPILOT'S RADIO CIRCUITS OF THE COCKPIT
VOICE RECORDER TAPE FRCM UNITED AIR LIHES FLIGHT 266, N7434~,B-727,
WHICH CRASHED INTO THE SEA. SHORTLY AFTER lAKEOFF FROM LOS ANGELES
IHTERMATIONAL AIRPORT, LOS ANGELES, CALIPORHIA, ON J A I T O ' 18, 1969.
Legend
CAM
-
Cockpit area microphone circuit
1
-
Voice identified as the Captain's
2
-
Voice identified as the Copilot's
KDO
-
TOE
-
Radio transmission from Los Angeles Tower's
Local Control Position
LAX DR
-
Radio transmission from Los Angeles Departure
Radar
%
-
Unrelated Radio Transmissions
#
Non-pertinent word or phrase
(1
-
---
-
3
Voice identified as the Engineer's
Radio transmission from UAL 266
Words enclosed within parentheses are not clearly
understood and are subject to interpretation. Those
shown represent the Interpretations of what the
speaker said.
Series of flashes indicates a pause in a transmission.
Transcript begins with flight's clearance for takeoff. When
clearance is received, the aircraft is holding position for takeoff
on Runway 24.
Intentionally Left Blank
in Original Document
TIME
-
CORPEBT
SOURCE
1816: 58
TWR
1817: 00
m
United two s i x t y s i x cleared f o r takeoff
2
United two s i x s i x r o l l i n g
:02
CAM1
last t h r e e items
:05
CAM3
Engine start switches
:06
CAM2
(Three on)
:07
CAM3
Anti skid
:10
CAM2
On (release)
1817:11
CAM?
(yeah t h a t 1s good)
CAM?
O i l cooler (comin) ground off
CAM?
(You kicked o f f Dick?)
CAM2
They're s t a b i l i z e d
CAM1
Take off t h r u s t
CAM2
Set
CAM2
Looks good
%%%
CAM2
One hundred
CAM2
One t e n
CAM2
One twenty
CAM2
VR
CAM2
V2
CAM 1.
Gear up
CAM2
Gear up
TWR
United two s i x t y s i x contact departure control
RDO2
Changing
%%$
1818: 09
CAM1
(YOUhandle t h e s e t h i n g s ) l i g h t on t h e c o n t r o l s
CAM 2
Yeah
CAM1
1818: 13
:1 5
CAM2
Five
RID2
United two s i x s i x on departure
LAXER
United two s i x t y s i x Los Angeles departure
c o n t r o l r a d a r contact, t u r n r i g h t heading
two seven zero r e p o r t l e a v i n g t h r e e thousand
EDO 2
Two seven zero wilco
CAM1
You have a green two
CAM2
Two
CAM
Sound of warning b e l l heard
CAM2
##
CAM1
What t h e h e l l was t h a t ?
CAM2
Number one f i r e warning, Arn
CAM1
OK, l e t s t a k e c a r e of t h e
CAM2
Pull it back f o r you?
CAM1
Yeah, p u l l it back
CAM 2
OK
CAM
Sound of warning horn heard
CAM2
That p u t s u s on one
CAM 1
Huh?
CAM2
T h a t ' l l put u s on one generator
CAM1
Yeah, watch t h a t e l e c t r i c a l loading
CAM2
Everything o f f ?
##
- - - - - warning
generator t o o
RDO 2
Ah-departure United two s i x s i x
IAX VS.
United two s i x t y s i x go ahead
m
Ah we've had a f i r e warning on number one engine,
we shut down we'd l i k e t o come back
2
LAX TS.
United two s i x t y s i x roger what i s your present
altitude?
CAM
CTE operation stopped
CAM
GVB resumed operation a t an indeterminate l a t e r
time
CAM?
Fields out
CAM
3
We're gonna get screwed up
CAM3
#,
CAM2
Keep it going up Arnie you're a thousand f e e t
CAM2
P u l l it up
CAM
End of recording. CVR ceased t o operate
I don't know (what I
s
going on)
Intentionally Left Blank
in Original Document
DarnDO CAM
. CVR OPERATION RESUMED A 1 AN INOETERMINATE 11ME
Darn.OO.5 CAM-? : FIELDS OUT
Darn
CAM 1
Darn
A
Darn-06
CAM-;
3
OOD008
CAM-2
OOOftOT
CAM
l n f f f , UA 266
WE'VE IIAO A FIRE WARNING ON
WE SHUT
NUMBER CUE EWINC
DOWN Wf'O LIKE TO COME BACK
Q SWEIPS 1 0 LOSS Of SICONDAtYl
WE'RE GOING TO GET SCREWED UP
. #,
I D O N 1 KNOW W K A I ' S GOING ON1
: KEEP 17 GOING UP ARNIE YOll'RE A THOUSAND FEET
PULL 1 1 U P
.
CVR OPtRAIIQN STOPPED 9 SECONDS AFTER RESUMPIION
CAM7
18i8W
C M ~ .
t VthH. WATCH IHhI ILECIRCChL LOAOING
1 8 1 8 - y
LOST PRIMARY TARGET--/
W
1818-48
CAM-?
:
THAT W I L L PUT US
: EVERYTHING
O M GENEHAIOR
OFf
lfll8.76.5
CAM I
YOU HAVE A GREEN TWO
181/55
LC ? CUMIACI O I P A R l l l R l CONTROI
E A R TURN RIGHI HEADING TWO
SIX 1111 ZERO SIX ZERO
Ã
WRECUAGE SITE
33"56'56" H.
na"39'30 w
IHREI THOUSAND FIVE HUNDRED
WHAT'S YOUR AIIITUDE NOW
1819-70 OS-7
8 : 5
!C-7
UNITED I W O SIXTY S I X CLIARIO
FOR TAKEOH
I f t l l E O TWO SIXTY SIX MAINTAIN
THREE 1HOUSAHD AND SAY YOUR
ALIITUDI
UA 7 W W I T 1 0 W O 5 1 1 5 t X R N L I N G
R18W
CAM 1
.
CAM 7
. VIA"
. FLAPS
. FIVI
I
1818%
CAM 7
. NUMBER O W FIRE WARNING, ARM
. OK. LETS 1AKT CARE 01 II#E . .
1818-36
CAM 1
I8iRdO
CAM 2
PULL IT BACK I O R YOU'
181842
CAM I
YEAH PUH I T BACK
CAM 2
OK
CAM2
WARMNG
(YOU HANOLE THESE [ I ( l N G S l
I I G h l ON THE CONTROLS
AH - F I V E .
. .,
8 1 8 11
UA 266 UNIlTO ?0 S I X I Y SIX ON O I P A R I ~ I R I
U M H D I W P SIXTY SIX tOS ANt.lE'i
OS-2
O!PARIURE CUNIROI RADAR COMHCT
181821
UA-766
IURK RICH! HEADING 1AO SEVEN ZERO
REPORI LEAVING THRTI THOUSAND
[WO SEVEN ZERO WlLCO
'
'
\
\
NATIONAL TRANSPORTATION SAFETY BOARD
DEPARTMENT OF TRANSPORTATIOH
Washington, D C ,
APPROXIMATE FLIGHT PATH CHART
UAL 266. B-727. N7434U
{BASED ON ATC ¥N CVR 0 A H I
ACCIDENT-APPRO< 11.3Ml WEST LOS ANGELES AIRPOR
Ian. 18. 1 9 6 9
Intentionally Left Blank
in Original Document