AIRCRAFT ACCIDENT REPORT OZARK AR I LINES, INC. FAIRCHILD HILLER FH-2276, N42l5 NEAR THE LAMBERT ST. LOUIS INTERNATIONAL AIRPORT ST. LOUIS, MISSOURI

-

JULY 23, 1973 Adopted: April 24, 1974

NATIONAL TRANSPORTATION SAFETY BOARD Washington, D.C. 20591 Rieport Number: NTSB-AAR-74-5

TECHNICAL REPORT STANDARD TITLE PAGE

. ReDort No. - - . T i t l e and S u b t l t i e

I 2.Government Accession No.

I 3.Reclpient's Catalog No. 5.Report Date April 24. 1974

ark Air Lines, Inc., F a i r c h i l d - H i l l e r FH-2276, ,215 Near the Lambert-St. Louis International St. I-uri. J u l v 23. 1973

1 '

6.Performing Organization Code

B.Performlng Organization

%or(s)

Report No.

. Performing Organization Name and Address National Transportation Safety Board Bureau o f Aviation Safety Washington, D.C. 20591

I

10.Work Unlt No. , 1233-C 11.Contract or Grant No. 13.Type of Report and

Perlod Covered Z.SDonsorina Aaencv Name and Address NATIONAL TRANSPORTATION SAFETY BOARD Washington, D. C. 20591

I t

A i r c r a f t Accident Report J u l y 23, 1973 14.Sponsoring Agency Code

I

I

5.Supplementary Notes

n i s report contains no new recomnendations 6.Abstract Ozark Air Lines F l i g h t 809, FH-227B(N4215) crashed 2.3 miles southeast ' the Lambert-St. Louis International A i r p o r t , i n S t . Louis, Missouri. about 1743 central daylight m ti e on July 23, 1973. O f the 44 persons on the a i r c r a f t , 38 were k i l l e d . The a i r c r a f t was destroyed by impact and f i r e . While F l i g h t 809 was making an ILs approach t o runway 30L a t Lambert-St. Louis a severe thunderstorm w i t h heavy rain, strong winds, and r o l l clouds moved across the approach end of the runway and the l o c a l i z e r course from the southwest. After passing the outer marker, the a i r c r a f t descended below the g l i d e Slope, entered an area o f heavy rain, was struck by lightning, and crashed. There was no i n - f l i g h t damage to, o r malfunction of. the a i r c r a f t ' s structure. powerplants, o r systems. There was no evidence t h a t l i g h t n i n g had Caused a malfunction o f an essential system o r s t r u c t u r a l damage. The National Transportation Safety Board determines t h a t the probable cause of the accident was the a i r c r a f t ' s encounter w i t h a downdraft following the captain's decision t o i n i t i a t e and continue an instrument approach i n t o a thunderstorm. The captain's decision probably was influenced by the lack Of a timely issuance of a Severe weather warning by the National Weather Service, and the improper assessmerit of the weather conditions i n the terminal area by the flightcrew and the f l i g h dispatcher.

1 7 . W Words

Aircraft

Accident. F a i r c h i l d - H i l l e r

Weather Service Severe S t o h Forecast Center 19.Security C l a s s i f i c a t i o n

(of t h i s report)

UNCLASSIFIED NTSB Form 1765.2 (11/70)

20.Security Classification (of t h i s page) UNCLASSIFIED

ii

3.

I

118.Dlstribution Statement

1

I

I

Information Service Springfield, Va. 22151 21.No. of Pages 22.Price

43

1. 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 2. 2.1 2.2

SY In

Hi

Ir

Dt 01

c1 A M, A

c

p F 1

I

.

I

TABLE OF CONTENTS

.

1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 1 11 1.12 1.13 1.14 1.15 1.16 1.17 2 2.1 2.2

.

.

3

.

...................... ................... ................. ................ ................ ................... .................. ................ ............. ................. ................... ........... .................. ...................... ........ ........................ .................. ................. .................. ............... ...................... ..................... ................... ................. ...................

Synopsis Investigation History o f F l i g h t I n j u r i e s t o Persons Damage t o A i r c r a f t Other Damage Crew Information A i r c r a f t Information Meteorological Information Aids t o Navigation Comnunications Aerodrome and Ground Faci 1it i e s F l i g h t Recorders Wreckage Medical and Pathological Information Fire Survival Aspects Tests and Research Other Information Analysis and Conclusions Analysis Conclusions (a) Findings (b) Probable Cause Recommendations Appendices Appendix A Appendix B Appendix C Appendix D Appendix E Appendix F

...... ......... ........

I n v e s t i g a t i o n and Hearing Airman Information A i r c r a f t Information Jeppesen Approach Chart National Weather Service Radar Photos Safety Recommendations

....... .......

iii

2 2

5 5

5 5 6 6 10 10 11 11 12 14 14 14 15 16 16 16 23 23 24 24 27 28 29 30 31 33

NATIONAL TRANSPORTATION SAFETY BOARD WASHINGTON. D.C. 20591

AIRCRAFT ACCIDENT REPORT Adopted:

A p r i l 24, 1974

OZARK A I R LINES, INC. FAIRCHILD HILLER FH-227B, FH-227B. N4215 NEAR THE LAMBERT ST OUIS INTERNATIONAL INTERNATIONAL AAIRPORT IRPORT ST.. L LOUIS ST. LOUIS, MISSOURI JULY 23. 1973

-

SYNOPSIS

About 1743 c'.d.t. on July 23, 1973, Ozark Air Lines F l i g h t 809, a FH-227B (N4215). crashed 2.3 miles southeast o f the Lambert-St. Louis International A i r p o r t , i n S t . Louis, Missouri. Forty-one passengers and three c r e w m b e r s were aboard the a i r c r a f t . Thirty-seven passengers and one crewmember received f a t a l i n j u r i e s . The a i r c r a f t was destroyed by impact and f i r e . While F l i g h t . 8 0 9 was making an instrument landing system (ILS) approach t o runway 30L on Lambert-St. Louis, a severe thunderstorm with heavy r a i n , strong winds, and r o l l clouds moved across the approach end o f the runway and l o c a l i z e r course from the southwest. A f t e r passing the outer marker, the a i r c r a f t descended below the g l i d e slope, entered an area o f heavy r a i n , was struck by l i g h t n i n g , and crashed. There was no i n - f l i g h t damage to, o r malfunction o f , the a i r c r a f t ' s structure, powerplants, o r systems. There was no evidence t h a t l i g h t n i n g caused any malfunction o f essential systems o r caused s t r u c t u r a l damage. The National Transportation Safety Board determines t h a t the probable casue o f the accident was the a i r c r a f t ' s encounter w i t h a downdraft following the captain's decision t o i n i t i a t e and continue an instrument approach i n t o a thunderstorm. The captain's decision probably was i n fluenced by the lack o f a t i m e l y issuance o f a severe weather warning by the National Weather Service, and the improper assessment o f the weather conditions i n the terminal area by the flightcrew and the f l i g h t dispatcher. As a r e s u l t o f the accident, the National Transportation Safety Board made s i x recomnendations t o the Federal Aviation Administration.

- 2 -

1.

1.1

INVESTIGATION

History o f F l i g h t

Ozark Air Lines F l i g h t 809, an FH-227B (N4215), was a regularly scheduled passenger f l i g h t between Nashville, Tennessee, and S t . Louis, Missouri. It made scheduled stops a t Clarksville, Tennessee, Paducah, Kentucky, Cape Girardeau, Missouri, and Marion, I l l i n o i s . The f l i g h t departed Marion, I l l i n o i s , a t 1705 Jl on July 23, 1973, with an instrument f l i g h t rules (IFR) f l i g h t plan t o Lambert-St. Louis International Airport. Forty-one passengers and three cremnembers were on board. The f l i g h t proceeded v i a the V-335 airway toward S t . Louis without d i f f i c u l t y . The f l i g h t was under the radar surveillance and control o f the Kansas City Air Route T r a f f i c Control Center (KCC). A t 1726:47.7. the KCC c o n t r o l l e r requested t h a t F l i g h t 809 make a 360' t u r n t o the r i g h t . He advised t h a t there would be about a 5-minute delay and t h a t the r i g h t t u r n would keep the f l i g h t clear o f the weather. The flightcrew indicated t h a t they would comply with the request.

The cockpit voice recorder (CVR) tape indicates t h a t imnediately a f t e r the c o n t r o l l e r ' s request, the f i r s t o f f i c e r said, "We're not going t o be able t o make it. I don't know, unless we follow it inbound." A f t e r the captain r e p l i e d "Okay," the first o f f i c e r asked "That's Okay?" The captain said "Yeah." The first o f f i c e r said, " I t ' s about 30 miles then from us, between us and the outer marker." The captain replied, "About over the outer marker," t o which the f i r s t o f f i c e r responded,, "That's r i g h t . " A t 1728:52.3,

the KCC c o n t r o l l e r cleared the f l i g h t t o proceed t o the A t 1729:47, the f i r s t o f f i c e r transmitted, "Approach, t h i s i s Ozark eight oh nine, seven thousand, w i t h Quebec." 2 The pertinent information i n the Quebec broadcast was: Estimated cei ing-4,000 f e e t broken, v i s i b i l i t y - 5 miles. haze and smoke, wind-120° a t 8 knots, temperat~re-92~,a1timeter-30.06. ILS runway 12R approaches i n use, landing and departing runways 12. The approach c o n t r o l l e r respond: "Orark e i g h t oh nine, Roger, maintain seven thousand and, continue toward the VOR, be vectors runway three zero l e f t ILS." The f i r s t o f f i c e r acknowledged w i t h "Roger." S t . Louis VOR and t o contact S t . Louis Approach Control

.

f

...

The first o f f i c e r then called Ozark operations personnel on the company radio frequency and reported t h a t the r i g h t engine f u e l boost pump and the main i n v e r t e r were inoperative. Then he called the S p i r i t o f S t . Louis A i r p o r t Unicorn and asked the operator t o inform a local general aviation company t h a t he would be 15 o r 20 minutes l a t e .

'

Unless otherwise specified, a l l times herein are.centra1 daylight, based on the 24-hour clock. J2 An Automatic Terminal Information Service (ATIS) broadcast of a i r p o r t t r a f f i c and weather conditions

.

Betw radar vec southeasl the f l i g l the f l i g l t h a t the

At tower 10 oh nine, The firs The con1 it's twt holding o f f icer At like a

now. 'I

transmi TI of the appear' prow was ab radar tried

the al

way

C'

A north execu conti then acCOI left a i rc1 d i sal

- 3 -

Between 1732:26 and 1739:22. the approach c o n t r o l l e r gave F l i g h t 809 radar vectors through an area o f thunderstorm c e l l s t h a t l a y south and southeast o f the S t . Louis A i r p o r t . A t 1740:12.9, the c o n t r o l l e r cleared the f l i g h t f o r an ILS approach t o runway 30L. A t 1740:42.6, he cleared the f l i g h t c r e w t o contact the S t . Louis Control Tower and informed them that the f l i g h t was 2 miles from Berkley. (See Appendix D.)

A t 1741:04.3, F l i g h t 809 established comnunications w i t h the S t . Louis tower l o c a l c o n t r o l l e r . A t 1742:00.9, the c o n t r o l l e r said, "...Ozark e i g h t oh nine, you're i n s i g h t and cleared t o land runway three zero l e f t . . .'I The f i r s t o f f i c e r acknowledged the clearance and asked f o r wind information. The c o n t r o l l e r responded: "Wind i s . i t ' s been gusting, i t ' s r i g h t now, i t ' s two two zero. I t ' s been around t o about three f o u r zero degrees, holding a t twenty b u t occasional gust up t o t h i r t y - f i v e . " The f i r s t o f f i c e r replied, "Roger."

...

A t 1742:31, the l o c a l c o n t r o l l e r said, "Ozark e i g h t oh nine, it looks l i k e a heavy r a i n shower moving r i g h t across the approach end o f the runway now." The f i r s t o f f i c e r r e p l i e d , "Roger, we see it." That was the l a s t transmission f r o m the f l i g h t . The CVR stopped a t 1743:24. The l o c a l c o n t r o l l e r stated t h a t he l o s t s i g h t o f the a i r c r a f t because o f the r a i n . U n t i l t h a t time, he had observed F l i g h t 809 executing what appeared t o be a normal ILS approach. He continued t o f o l l o w the f l i g h t ' s progress on the tower radar, b u t l o s t primary radar conta.ct when the f l i g h t was about 2 miles from the runway. When he observed the alpha-numeric radar t r a c k o f the a i r c r a f t move t o the l e f t o f the l o c a l i z e r course, he t r i e d unsuccessfully t o make r a d i o contact w i t h the f l i g h t . F l i g h t 809 crashed i n t o a r e s i d e n t i a l area about 2.3 miles southeast o f the approach end o f runway 30L and about 700 f e e t south o f the extended runway center1 ine. An aeronautically q u a l i f i e d witness, who was about 2,000 f e e t northnorthwest o f the accident s i t e , stated t h a t he had observed the a i r c r a f t executing what appeared t o be a normal ILS approach. As the a i r c r a f t continued the approach, it suddenly ascended about 400 t o 500 f e e t and then r a p l d l y descended t o 200 f e e t above the ground. Shortly thereafter, according t o the witness, l i g h t n i n g struck the wing j u s t outboard o f the l e f t engine. The l i g h t n i n g was followed by a r o l l i n g f l a s h o f f i r e . The a i r c r a f t again lost a l t i t u d e and, a f t e r several apparent "evasive maneuvers," disappeared i n t o the r a i n and trees.

- 4 -

Other witnesses, who were east-southeast o f the accident s i t e and a t various points along t h e f l i g h t p a t h o f F l i g h t 809, reported t h a t the a i r c r a f t ' s a1ti tude had appeared "much lower than normal .I' They stated t h a t it had been r a i n i n g heavily and t h a t the wind had been blowing very hard from t h e southwest. One witness, who was about 1.4 miles east-southeast o f the accident s i t e , said t h a t the a i r c r a f t had flowno w l over her house and had disappeared i n t o an area o f heavy r a i n west-northwest o f her position.

A Trans World A i r l i n e s Boeing 727, F l i g h t 244, approached runway 30L about 1.5 minutes before F l i g h t 809. The captain o f F l i g h t 244 stated t h a t because o f a strong u p d r a f t he had d i f f i c u l t y i n slowing h i s a i r c r a f t t o the proper f i n a l approach airspeed, Because he was unable t o e s t a b l i s h the desired landing configuration and airspeed, he executed a missed-approach. He said t h a t he had been c l e a r o f a l l clouds about 1.000 f e e t above the ground and 4 miles southeast o f the runway. About 1/4- t o 1/2-mile t o h i s l e f t , the captain o f F l i g h t 244 saw a "wall o f water" t h a t p a r a l l e l e d the l o c a l i z e r course and curved around the southwest corner o f the a i r p o r t . A l i g h t twin-engine a i r c r a f t t h a t preceded F l i g h t 244 on the same ILS approach landed on runway 30L a t 1740. The p i l o t stated t h a t he had d i f f i c u l t y c o n t r o l l i n g h i s a i r c r a f t a f t e r i n t e r c e p t i n g t h e l o c a l i z e r course about 4 miles southeast of the outer marker (OM), Because o f a strong updraft, he was unable t o descend f r o m 6,000 f e e t mean sea l e v e l (m.s.1.). A downdraft near the OM caused h i s a i r c r a f t t o drop 3,500 f e e t per minute, the maximum r a t e displayed on the instantaneous v e r t i c a l v e l o c i t y i n d i c a t o r . He flew the a i r c r a f t o u t o f the downdraft near glidepath a1ti tude several miles f r o m t h e end o f the runway, continued the approach, and landed. Several minutes l a t e r , a dark, heavy rainstorm, w i t h strong, gusty surface winds, moved across the a i r p o r t from the west and northwest. The captain o f F l i g h t 809 stated t h a t except f o r two minor malfunctions o f the a i r c r a f t ' s systems, the f l i g h t had been r o u t i n e u n t i l it a r r i v e d i n the S t . Louis terminal area. As the f l i g h t approached S t . Louis, the captain used the airborne weather radar, which was operating properly, t o i d e n t i f y thunderstorm c e l l s . The captain r e c a l l e d overshooting the l o c a l i z e r course and disconnecting the a u t o p i l o t t o make the necessary correction t o r e t u r n t o course. He could see the runway from outside the OM. A f t e r the tower c o n t r o l l e r had informed him o f the heavy r a i n shower which existed over the approach end o f the runway, he could still see the end o f the runway through the r a i n . As the f l i g h t proceeded inbound from the OM the captain noticed what appeared t o be a r o l l cloud below t o h i s l e f t , and p a r a l l e l t o the l o c a l i z e r course, and a "wall o f clouds" along the southern and western circumference o f the airport

.

.

l i k e hai applying consciot and atte ACC

scene at had beer the cap1 struck I had O C C ~ the acc 1.2

I" -I

1.3

0 T

1.4

C

1 sever1

1.5

!

- 5 -

The captain could r e c a l l nothing e l s e except: Hearing something l i k e h a i l h i t t i n g the airplane; pushing the t h r o t t l e s forward; and applying back pressure t o the control column. He r e c a l l e d becoming conscious i n the wreckage, f e e l i n g the i n j u r y t o h i s head, seeing f i r e , and attempting t o f r e e himself and the f i r s t o f f i c e r . According t o an Ozark Air Lines employee who had a r r i v e d a t the scene about 30 minutes a f t e r the accident, the captain said t h a t he had been struck by l i g h t n i n g . When he t e s t i f i e d a t the p u b l i c hearing, the captain could n o t r e c a l l having made the statement o r having been struck by l i g h t n i n g . The f i r s t o f f i c e r d i d n o t remember anything t h a t had occurred on the day o f the accident. The geographic coordinates o f the accident s i t e are 38' 43'07"N. l a t i t u d e and 90' 18'30"W. longitude. ~

~~

1.2

1.3

I n j u r i e s t o Persons Injuries

Crew -

Fatal

1

37

0

Nonfatal

2

4

0

None

0

0

Passengers

Other

Damage t o A i r c r a f t The a i r c r a f t was destroyed.

1.4

Other Damage

Trees and bushes were destroyed o r damaged, and a power l i n e was severed. Two residences were s l i g h t l y damaged. 1.5

Crew Information

The captain and f i r s t o f f i c e r were c e r t i f i c a t e d arkording t o regulations. A ll crewmembers received the t r a i n i n required by the company and by the Federal Aviation Administration (FAA

3.

The captain was upgraded from first o f f i c e r i n August 1971. He d i d not begin f l y i n g as captain, however, u n t i l March 22, 1973, when he received h i s captain's checkout i n the FH-227. From March 22, 1973, t o the day o f the accident, he acquired about 66 f l i g h t - h o u r s as p i l o t - i n cmnand o f FH-227 a i r c r a f t .

- 6

-

Because o f an employee s t r i k e , n e i t h e r the captain nor t h e f i r s t o f f i c e r flew w i t h Ozark Air Lines from A p r i l 19, 1973, t o J u l y 1, 1973. From J u l y 1 t o the day o f the accident, the captain and f i r s t o f f i c e r flew 30:25 and 59:30 hours, respectively, i n the FH-227. They both had been o f f duty about 19 hours before they reported f o r duty a t 1000 on the day o f the accident. (See Appendix B.) 1.6

.

A t them ite o f the accident, the gross weight o f N4215 was about 43,000 pounds. The center o f g r a v i t y and gross weight were w i t h i n prescribed m i l t is

.

The a i r c r a f t departed Paducah, Kentucky, w i t h a f u l l load o f J e t A kerosene f u e l aboard. About 4,830 pounds o f f u e l were aboard when the plane crashed. (See Appendix C.) Meteorological Information Synoptic S i t u a t i o n The surface weather c h a r t f o r 1600 on J u l y 23, 1973, showed a wave on a quasi- stationary f r o n t over northeastern Missouri. One p o r t i o n o f the f r o n t extended southwestward from the wave and another p o r t i o n extended east-southeastward. The c h a r t f o r 1900 showed a warm f r o n t which extended northeastward from southern Kansas t o northwestern I l l i n o i s , then southeastward t o northeastern Kentucky. A semicircular squall l i n e extended clockwise from c e n t r a l I l l i n o i s , about 60 miles east and 60 miles southeast o f S t . Louis, t o Kansas City. A meso-scale high-pressure system was centered near S t . Louis. Surface Weather Observations

st.

1725

a1t

1742

A i r c r a f t Information

Ozark Air Lines owned and operated the FH-227B, N4215. Except f o r the cabin attendant's seat, which d i d n o t meet FAA regulations, the a i r c r a f t was c e r t i f i c a t e d , equipped, and maintained according t o approved company procedures and FAA regulations

1.7

-- @ --

Louis

1654 - Estimated c e i l i n g 4,000

f e e t brokeg, 25,000 feetoovercast, v i s i b i l i t y - 6 miles, temperature-90 F., wind-130 12 knots, cumulonimbus northwest t o v i ng east-northgast , towering cumulus north, wind 090 v a r i a b l e t o 170

.

--

cas win inc eas Pre

1746

knc

17: Cl'

at 69

- 7 -

1725 - S ecial, 1,200 f e e t scattered, measured ceiling-2,500 f e e t k v i s i b i 1 i t y - 1 0 miles, wind-3200 22 knots, gusts 26 knots, a1timeter setting-30.09 inches, pressure unsteady. 1742 - Special , measured c e i l i n g 1,100 f e e t broken,2,800 f e e t overcast, v i s i b i l i t y - 1 0 miles, thunderstorm, heavy r a i n showers, wind 300" 29 knots, gusts 30 knots, a l t i m e t e r setting-30.15 inches. Thunderstorm began a t 1737, thunderstorm west, moving east, occasional l i g h t n i n g i n clouds and cloud t o ground, pressure r i s i n g r a p i d l y ; r a i n began a t 1732.

1746 - S e c i a l , measured ceil.ing 1,100 f e e t overcast, v i s i b i l i t y - 1 mile, un erstorm. bheavy r a i n showers, wind-2200 20 knots, gusts 33 knots, a1timeter setting-30.22 inches. Thunderstorm began a t 1737, thunderstorm overhead, moving east, frequent l i g h t n i n g i n clouds and cloud t o ground, pressure r i s i n g r a p i d l y , r a i n began a t 1732, runway 24 visual range-2,400 f e e t v a r i a b l e t o more than 6,000 feet. 1755 - Record S e c i a l , i n d e f i n i t e c e i l i n g 200 f e e t obscured, v i s i b i l i t y -.storm, heavy r a i n showers , sea l e v e l pressure1,023.7 m i l l i b a r s , temperature-72' F., dew point-720 F., wind-

I

1,

220" 24 knots, gusts 33 knots, a l t i m e t e r setting-30.24 inches. Thunderstorm began 1737, thunderstorm overhead, moving east, frequent l i g h t n i n g i n clouds and cloud t o ground, pressure unsteady, peak wind 190" 33 knots a t 1745; r a i n began a t 1732, runway 24 visual range-1,400 f e e t variable t o more than 6,000 feet, p r e c i p i t a t i o n 1.03 inches

.

The r a i n f a l l record i n the National Weather Service Forecast Office (NWSFO) a t the a i r p o r t showed t h a t heavy p r e c i p i t a t i o n began about 1740; about 1.55 inches o f r a i n f e l l i n the following 45 minutes. A r a i n f a l l recorder which was located about 1 m i l e southeast o f the ap roach end o f runway 30L, recorded about 1.75 inches o f r a i n f a l l between 740 and 1800.

!

National Weather Service

(NS)Forecasts

Part o f the a v i a t i o n terminal forecast issued by the S t . Louis NWSFO a t 1140, v a l i d from 1200 on J u l y 23, 1973.to 1200 on July 24, 1973, was as follows: S t . Louis, 1500-0100: C e i l i n g 3,000 feet broken, 10,000 f e e t broken, wind-1800 a t 8 knots, occasional ceiling-3,000 f e e t overcast.,visibility6 miles, thunderstorm, moderate r a i n showers. This forecast was n o t changed u n t i l 1740.

~

I

i I

I i

- 8 -

The a v i a t i o n area forecast issued a t 1340 by the NWSFO a t Chicago, I l l i n o i s , v a l i d from 1400 on J u l y 23, 1973, t o 0200 on J u l y 24, 1973, predicted widely scattered showers and thunderstorms over Missouri. There was no SIGMET o r AIRMET advisory i n e f f e c t f o r any p a r t o f Missouri o r I l l i n o i s a t the time o f the accident. Radar Weather Observations The NWSFO a t S t . Louis was equipped w i t h a WSR-57 weather radar u n i t on the day o f the accident. The WSR-57 i s an S-band radar w i t h an e f f e c t i v e range o f 250 miles. The elevation o f weather echoes i s displayed on a range height i n d i c a t o r and the p o s i t i o n o f weather echoes i s displayed on a plan p o s i t i o n i n d i c a t o r (PPI). Measurements o f elevation 100 miles from the antenna and beyond are subjest t o increasing error, and the 45O m i l t i of antenna tilt precludes measurements above 55,000 feet w i t h i n 10 miles of the antenna. Photographs o f the PPI display a t p e r t i n e n t time i n t e r v a l s are included i n Appendix E. The NWS radar observer records observations a t l e a s t once an hour when weather echoes e x i s t and more frequently when conditions require them. The observer codes the weather radar data and transmits them t o the National Severe Storms Forecast Center (NSSFC) a t Kansas City, Missouri. The data were scheduled t o be sent v i a teletype a t 40 minutes past the hour. A t NSSFC, the data are plotted, analyzed, and developed i n t o radar sumnary charts o f the United States. The charts are transm i t t e d t o various organizations v i a f a c s i m i l e c i r c u i t s 14 times every 24 hours. The NSSFC also issues tornado and severe storm watches t o a f f e c t e d geographic areas. The radar summary charts issued by NSSFC a t 1640 and 1738 on J u l y 23 showed scattered thunderstorms i n the S t . Louis area. Portions o f the S t . Louis n a r r a t i v e weather radar sumnaries prepared by the forecast o f f i c e a t S t . Louis f o r the times indicated were as follows :

1640 -

...

“Thunderstorms continue over eastern Missouri eastern edge from 30 miles west o f Springfield, I l l i n o i s , southward t o j u s t west o f S t . Louis t o 100 miles southeast o f S t . Louis i n the southern t i p o f I l l i n o i s . p r e c i p i t a t i o n i s moving i s o l a t e d storms are extoward the northeast a t 20 mph. pected t o produce heavy r a i n . strong, gusty winds and possibly h a i l as they move northeastward during the next few hours, ’’

..

.. ..

1738 - “Conditions were s i m i l a r t o those described i n the 1640 sumnary, except f o r the l i n e o f thunderstorms which was positioned over S t . Louis, . . . w i t h the most intense storms i n a l i n e 10 miles wide centered over S t . Louis and extending 20 miles north and south o f S t . Louis. . .”

- 9 -

Dissemination o f Weather Information The S t . Louis surface weather observations were transmitted through TelAutograph 4 J t o ,the FAA c o n t r o l tower cab and IFR room, the FAA Flight Service Station, Ozark Air Line F l i g h t Dispatch Center, and various other subscriber organizations a t the a i r p o r t . Information was transmitted several minutes a f t e r the observation had been made. The coded, b u t n o t the narrative, weather radar sumnaries were also transmitted through TelAutograph. A severe thunderstorm warning was so transmitted about 1748 on July 23. NWS personnel also broadcast weather information by FM r a d i o located i n the S t . Louis f a c i l i t y . The broadcasts include surface observations, n a r r a t i v e weather radar sumnaries, and severe weather warnings. Subscribers t o t h i s service can use muted receivers t h a t are activated automatically by the broadcast signal. A t 1742 on J u l y 23, NWS personnel broadcast a severe thunderstorm warning which n e i t h e r Ozark Air Lines nor the FAA heard, since they d i d n o t subscribe t o the service

.

Local surface weather observations and forecasts were also disseminated over Service A teletype f a c i l i t i e s t o various organizations, one o f which was the Ozark Air Lines F l i g h t Dispatch Center. Postaccident Observations Trees surrounding the accident s i t e were damaged by wind. The heaviest damage was i n an area which extended from a short distance northwest t o about 1 m i l e southeast o f the accident s i t e and approximately % m i l e on both sides o f the l o c a l i z e r course. A NWS expert estimated t h a t winds o f 65-70 mph would have been required t o cause such damage. Witnesses, who were ldcated about 5 miles south-southeast o f the accident s i t e , saw a mass o f debris r o t a t i n g counterclockwise near the ground. The time was between 1735 and 1745 on the day o f the accident. The wind damaged trees i n an area 450 f e e t wide and 1,500 f e e t long. The wind blew the r o o f o f a l a r g e b u i l d i n g a distance o f about 300 feet. Special Weather Study The National Weather Service prepared a special study o f the weather conditions i n the S t . Louis area. The study showed t h a t two d i s t i n c t squall l i n e s which contained thunderstorms had converged near the S t . Louis airport about the time of the accident. One l i n e was oriented nearly north-south (N-S) while the other was oriented east-southeast-west-northwest (ESE-WNW). Both l i n e s were moving i n a northeasterly d i r e c t i o n a t 30 knots. A machine on which the sender can w r i t e words, symbols, and numbers. This information i s then transmitted e l e c t r o n i c a l l y and reproduced graphically on a receiver.

- 10 A f t e r considering the temperature and humidity a t 1700, the NWS determined t h a t a parcel of a i r would become saturated a f t e r i t was l i f t e d a d i a b a t i c a l l y t o t h e 760-1nillibar l e v e l . I f it were l i f t e d t o the -500-1nillibar l e v e l , the parcel would be 3.50 C,.warmer than the surrounding a i r , and thereby would generate a h i g h l y a c t i v e thunderstorm c e l l . The r e s u l t i n g downrush of a i r w i t h i n the c e l l could produce surface winds w i t h gusts t o 60 knots and 1/2- to 3/4-inch h a i l a t o r near the surface Since the ESE-WNW squall l i n e was moving northeast a t 30 knots, downrush v e l o c i t i e s w i t h i n one o f the c e l l s would be added along the northern edge and subtracted along t h e southern edge. Consequently, strong, southerly surface winds o f 60-90 knots might have existed along the northern edge o f the l i n e as i t moved northeastward and perpendicular t o the l o c a l i z e r course, An a i r c r a f t north o f the l i n e would be f l y i n g i n an area o f strong updrafts. However, ifthe a i r c r a f t f l e w i n t o the l i n e , the a i r c r a f t would encounter strong downdrafts. The accident occurred during d a y l i g h t hours b u t i n heavy r a i n under dark overcast skies. 1.8

Aids t o Navigation

The S t . Louis a i r p o r t i s equipped w i t h approach surveillance radar and ILS f a c i l i t i e s . (See Appendix D.) A f t e r the accident, the radar and ILS equipment were ground-tested and the ILS was f l i g h t - t e s t e d . A ll components operated w i t h i n prescribed tolerances.

1.9

Conunications

Tests indicated t h a t p e r t i n e n t radios i n the S t . Louis tower were operational. The captain's transceiver was damaged s l i g h t l y . When tested, i t operated according t o manufacturer's specifications. The f i r s t o f f i c e r ' s transceiver sustained moderate compression damage t o the synthesizer assembly. A f t e r a serviceable synthesizer assembly was i n s t a l led, the transceiver operated properly. The FAA's tape of recorded a i r t r a f f i c c o n t r o l comnunications and the CVR tape indicated t h a t the a i r c r a f t ' s radios were functioning before impact. Under e x i s t i n g a i r t r a f f i c control procedures, neither the approach c o n t r o l l e r nor the t w e r c o n t r o l l e r has a u t h o r i t y t o deny a p i l o t ' s request t o make an approach o r landing, except when a i r c r a f t cannot otherwise be safely separated or controlled. The p i l o t i s responsible f o r adhering t o r u l e s and regulations which govern approaches and landings.

- 11 -

Controllers are responsible f o r providing the p i l o t w i t h the l a t e s t i o f f i c i a l weather observations. I n a d d i t i o n t o t h e i r primary function o f air t r a f f i c control, c o n t r o l l e r s also provide advisory service. This f advisory service includes advice and information provided t o p i l o t s t o a s s i s t them i n the safe conduct o f f l i g h t and a i r c r a f t movement. FAA tower c o n t r o l l e r s who are c e r t i f i e d weather observers are authorized : to make o f f i c i a l weather observations. However, i f a NWS weather ' s t a t i o n i s located a t the a i r p o r t , FAA c o n t r o l l e r s make o f f i c i a l observations only when the p r e v a i l i n g v i s i b i l i t y i s less than 4 miles. These c o n t r o l l e r s i may disseminate general weather information, such as, "large breaks i n the overcast," " v i s i b i l i t y lowering t o the south." o r s i m i l a r statements : which do not include s p e c i f i c values. Also, they may transmit t o p i l o t s or other ATC f a c i l i t i e s any weather observations derived. d i r e c t l y from instruments, p i l o t reports, o r radar without consulting the weather station. Otherwise, s p e c i f i c values f o r elements such as c e i l i n g and v i s i b i l i t y may be transmitted only i f they are obtained from a c e r t i f i e d observer o r from a r e p o r t composed o r v e r i f i e d by the o f f i c i a l weather station.

:.

1.10 Aerodrome and Ground F a c i l i t i e s The St. Louis

-

Lambert International A i r p o r t i s about 9 miles northThe a i r p o r t elevation i s 589 feet. It contains one set o f p a r a l l e l runways and two single runways. Three runways, 30L. 12R, and 24. are equipped w i t h ILS f a c i l i t i e s .

west o f downtown S t . Louis.

1.11

F l i q h t Recorders

N4215 was equi ped w i t h a F a i r c h i l d H i l l e r f l i g h t ~ d a t arecorder (FDR) model F-5424, s e r i a No. 2675, and a United Control cockpit voice recorder (CVR) model V-557, s e r i a l No. 1940.

P

The outer case o f the FDR was n o t damaged and the recording f o i l was i n good condition. The a l t i t u d e and airspeed traces were abnormal, a condition t h a t had existed during the preceding 77 f l i g h t s . The recorder was found i n the wreckage w i t h the s t a t i c pressure l i n e disconnected. The heading and v e r t i c a l acceleration traces operated properly. The CVR case and recording tape were n o t damaged. The q u a l i t y o f the information recorded on the captain's and first o f f i c e r ' s r a d i o channels was fair. The recording o f the cockpit area microphone (CAM) channel was poor. The i n p u t signal t o t h i s channel was derived from a single, omnidirectional, dynamic microphone which was mounted on the center overhead instrument panel. The CAM channel o f the tape operated i n t e r m i t t e n t l y for about 6 seconds, beginning 2 minutes before the end o f the recording. After t h i s i n t e r m i t t e n t operation, the sound l e v e l returned t o normal, and : one o f the crewembers said, "What was t h a t ? " About 13 seconds l a t e r , the i sound l e v e l dropped t o a low volume l e v e l f o r 1 second, returned t o normal

-

12

-

f o r 2 seconds, and dropped again t o a low volume l e v e l . It remained w l l e v e l u n t i l the end o f recording, 97 seconds l a t e r . a t t h a to The CVR, the CAM, and the microphone monitor u n i t were tested. The system operated w i t h i n specified tolerances. 1.1 2 Wreckage F i r s t , the a i r c r a f t struck t r e e tops about 55 f e e t above the ground. About 280 f e e t f a r t h e r west along the f l i g h t p a t h , the l e f t wing struck trees; 200 f e e t still f a r t h e r west, the a i r c r a f t struck a l a r g e sycamore tree. The a i r c r a f t continued i n a westerly d i r e c t i o n f o r about 140 feet, where it struck the ground. I t stopped on a h i l l s i d e near Lowen Drive i n Normandy, Missouri--a suburb o f S t . Louis. Damage t o the a i r c r a f t and the sycamore t r e e indicated t h a t the a i r c r a f t was i n a high noseup a t t i t u d e when i t struck the tree. On impact, both wings separated from the center wing section, j u s t outboard o f the engine nacelles. The r i g h t wing was damaged s l i g h t l y by f i r e near i t s separation p o i n t . F i r e also damaged the l e f t wing stub o f the center wing section, near the l e f t engine nacelle area. The center wing section separated from the a i r c r a f t , which created a large hole i n the fuselage. Portions o f ailerons and wing f l a p s remained attached t o both wing structures. Wing-flap-jackscrew measurements indicated t h a t the f l a p s were extended 27

.

Both main landing gears broke o f f . The nose gear was i n t a c t but severely damaged. The condition o f the down-lock assemblies and actuating cylinders indicated t h a t the landing gear had been i n the extended p o s i t i o n , The fuselage was found l y i n g on i t s l e f t side. The area where the l e f t wing j o i n s the fuselage was severely damaged. The area from the cockp i t a f t t o the p o i n t a t which the r i g h t wing j o i n s the fuselage was also extensively damaged. The fuselage broke open c i r c u m f e r e n t i a l l y j u s t a f t o f the cockpit. The cockpit section was found on Lowen Drive. The empennage section remained attached t o the a f t fuselage. The l e f t horizontal s t a b i l i z e r was broken chordwise by overload forces. The v e r t i c a l and r i g h t h o r t i z o n t a l s t a b i l i z e r s remained i n t a c t . The a i r c r a f t was examined f o r evidence o f l i g h t n i n g damage. About 75 randomly spacedpits,which ranged from 1/32- t o 1/8-inch i n diameter, were found on the e n t i r e length o f the underside o f the fuse'lage. Several s i m i l a r p i t s were found on the top surface o f the l e f t aileron. There was no other evidence o f e l e c t r i c a l arcing o r burning.

-

13

-

The ten p r e c i p i t a t i o n s t a t i c eliminators showed no evidence o f lightning damage. Antennae, waveguides, navigation and conspicuity l i g h t systems, c i r c u i t boards, t r a n s i s t o r s , and other e l e c t r o n i c components i n the c m u n i c a t i o n s and navigation equipment were examined f o r evidence 'of a high flow o f e l e c t r i c a l current; none was found. Both engines and p r o p e l l e r assemblies were recovered from the wreckage. Although the l e f t engine was only s l i g h t l y damaged, the r i g h t engine was extensively damaged. The turbine-to-reduction-gear torque shafts i n both engines were fractured. The condition o f the reduction gear components indicated that the propellers had stopped suddenly, while under power. The propeller blade angles were commensurate w i t h a f i n a l approach airspeed and power s e t t i n g . There was no evidence o f i n - f l i g h t malfunction o r f a i l u r e o f e i t h e r powerpl ant. The captain's and f i r s t o f f i c e r ' s altimeters were recovered i n t a c t . The barometric s e t t i n g was 30.04 inches on the captain's a l t i m e t e r and 30.02 inches on the f i r s t o f f i c e r ' s a l t i m e t e r . The f l i g h t c r e w was n o t aware t h a t the S t . Louis a l t i m e t e r s e t t i n g a t 1739 was 30.15 inches. The i n t e r n a l sector gear counterweight, mounting screw, and a compensator p i n were loose i n the instrument case o f the captain's a l t i m e t e r . The a l t i m e t e r contains two compensator pins, one behind the rocking s h a f t and the other behind the balance assembly support. The i d e n t i t y o f the loose compensator p i n was n o t established before i t s r e i n s t a l l a t i o n . Therefore, the a l t i m e t e r was tested first w i t h one and then w i t h the other compensator p i n removed. The a l t i m e t e r functioned w i t h i n tolerances a f t e r removal o f the p i n behind the rocking shaft. A f t e r removal o f the p i n behind the balance support assembly, however, an e r r o r o f +530 f e e t and e r r a t i c movement o f the pointer were recorded a t a pressure a l t i t u d e o f 1,000 f e e t . ViBration t e s t i n g d i d n o t cause e i t h e r p i n t o come loose from i t s normal p o s i t i o n . The sector gear counterweight was removed from the a l t i m e t e r and the instrument was tested. Tests showed t h a t a l t i m e t e r accuracy and performance were not s i g n i f i c a n t l y affected. Because the sector gear pivots and the f i r s t o f f i c e r ' s a l t i m e t e r were broken, the a l t i m e t e r could n o t be f u n c t i o n a l l y tested. There was no i n t e r n a l evidence o f preimpact damage.

- 14 1.13 Medical and Pathological Information Pathologists from the S t . Louis County Coroner's O f f i c e examined a l l the deceased passengers and the cabin attendant. They also conducted t o x i c o l o g i c a l studies o f blood samples from t h e deceased. Typical i n j u r i e s included compound f r a c t u r e s of the extremities, s k u l l fractures, crushed chests, dismemberment, f o u r t h degree burns, massive i n t e r n a l i n j u r i e s , and other traumatic i n j u r i e s . The cabin attendant's i n j u r i e s included a s k u l l fracture, crushed chest, and massive i n t e r n a l i n j u r i e s . Toxicological t e s t s indicated no evidence o f carbon monoxide o r hydrogen cyanide i n the deceased. Four passengers, who were seriously i n j u r e d i n the accident, were thrown c l e a r o f the fuselage during the crash sequence. Their i n j u r i e s included compound fractures t o t h e i r extremities ,vertebra fractures, r i b fractures, m u l t i p l e contusions, and severe lacerations t o the head and body. The captain received serious head, chest, and l e g i n j u r i e s . The f i r s t o f f i c e r received massive f a c i a l i n j u r i e s . The a i r c r a f t was n o t equipped w i t h crewmember shoulder harnesses, nor were they required. 1.14 Several smal 1 f i r e s broke o u t i n various portions o f the wreckage a f t e r f i n a l impact. A t 1746, the Normandy F i r e Protection D i s t r i c t Dispatcher was n o t i f i e d t h a t a house on Lwen Drive was on f i r e . F i r e and rescue equipment were dispatched imnediately and a r r i v e d a t the scene about 1749. The f i r e s were q u i c k l y extinguished. Rescue operations began immediately upon a r r i v a l o f the equipment. Several residents o f the area assisted.

1.15 Survival Aspects When the f i r e c h i e f r e a l i z e d the s e v e r i t y o f the accident, he requested f i v e more rescue u n i t s and a l l a v a i l a b l e ambulances. The rescue e f f o r t s were hampered by heavy r a i n , high winds, and some f l o o d i n g i n the area. The l a s t passenger was removed from the wreckage about 2215. T h i r t y - f o u r police departments p a r t i c i p a t e d i n the rescue and salvage a c t i v i t i e s ; 9 f i r e departments and 16 ambulances were dispatched. The Inspector o f the S t . Louis County Police a r r i v e d a t the scene about 1808. He established a communications comnand post and began coordinat i n g the dispatch and r o u t i n g o f ambulances and other rescue vehicles. He also directed. the control o f t r a f f i c t h a t began t o congest the accident area.

-

15

-

The seats i n the f i r s t three rows and i n rows 8 through 11 f a i l e d

i n a l e f t , forward d i r e c t i o n ; t h e seats i n rows 4 through 7 f a i l e d i n a right, forward d i r e c t i o n . 1.16 Tests and Research

When the captain's f l i g h t d i r e c t o r instrument ( C o l l i n s FD-108) was found i n the wreckage, i t displayed a comnand bar i n d i c a t i o n o f p i t c h down 10' and bank r i g h t . The instrument case was pressed i n t o the comnand bar gears, which were n o t movable. After the dent i n the case was removed, the comnand bars functioned normally during testing, as d i d other f l i g h t d i r e c t o r components. The captain's f l i g h t d i r e c t o r system, which consisted o f the f l i g h t d i r e c t o r instrument, f l i g h t c o n t r o l computer, and a m p l i f i e r , was tested t o determine what caused the pitch-down display.

I n n o m 1 ILS mode operation, the c o m n d bars i n the f l i g h t d i r e c t o r instrument i n d i c a t e t o the p i l o t the d i r e c t i o n i n which t o f l y the a i r c r a f t to intercept the ILS g l i d e slope and l o c a l i z e r course. When the a i r c r a f t i s d i r e c t l y on course and g l i d e slope, the command bars w l i be centered appropriately i n the instrument case. If the a i r c r a f t descends below the l i move toward the top o f the instrument glide slope, the c m n d bars w case, displaying a f l y - u p i n d i c a t i o n t o the p i l o t . A reverse i n d i c a t i o n i s displayed i f the a i r c r a f t i s above the g l i d e slope beam. Hwever, the system i s designed so t h a t when t h e a i r c r a f t exceeds

a 9.80 noseup a t t i t u d e , t h e v e r t i c a l gyro i n the f l i g h t control computer signals a comnand bar pitch-down display, regardless o f t h e a i r c r a f t ' s

p s i t i o n w i t h respect t o the ILS g l i d e slope beam. The gyro signal i s proportional t o the a i r c r a f t p i t c h angle when the angle exceeds 9.8' noseup. For instance, i f the a i r c r a f t i s positioned i n a 19.8' noseup a t t i t u d e , the v e r t i c a l gyro w i l.signal a comnand bar display o f 10' nosedown.

-

16

-

M e t a l l u r g i c a l t e s t s were made o f two sections o f the a i r c r a f t fuselage s k i n which contained p i t s believed t o have been caused b y l i g h t n i n g . These p i t s were s i m i l a r t o those produced by an e l e c t r i c a l arc when it contacts the surface o f the skin. The p i t s appeared t o have been f r e s h l y made, since they contained l i t t l e o r no d i r t and soot deposits

.

1.17 Other Information The Ozark Air Lines Operations Manual contained procedures f o r thunderstorm recognition and avoidance. The company's general p o l i c y was t o suspend operations over a route o r a p a r t i c u l a r area ifthunderstorms generated an unacceptable l e v e l o f turbulence. Also,, the compqny advised against penetrating any known thunderstorm c e l l which had been detected v i s u a l l y o r by airborne weather radar. The avoidance c r i t e r i a specified were: (1) The p i l o t should attempt t o av0i.d thunderstorms which are suspected t o be severe, by 20 miles a t a11 levels, and (2) he should attempt t o avoid a l l other thunderstorms by 10 miles a t a l l l e v e l s . With reference t o operations i n t o terminals with high- density t r a f f i c , l i t t l e space i s available the manual cautioned p i l o t s as follows: t o permit deviations; therefore, you must evaluate the weather s i t u a t i o n i n the terminal area well p r i o r t o a r r i v a l and inform ATC of your i n t e n t i o n s so t h a t the area and approach c o n t r o l l e r s can take appropriate a c t i o n t o avoid c o n f l i c t . "

". . .

2. ANALYSIS AND CONCLUSIONS 2.1

Analvsis

General--Except f o r the cabin attendant's seat, the a i r c r a f t was equipped, c e r t i f i c a t e d , and maintained according t o company procedures and FAA requirements. The cabin attendant's seat d i d n o t conform t o FAA regulations, and i t should n o t have been c e r t i f i c a t e d f o r use. E f f e c t i v e August 27, 1973, the c a r r i e r discontinued use o f t h i s seat. (See Appendix F.) There was no evidence o f any f a i l u r e o r malfunction o f the a i r c r a f t ' s s t r u c t q e , powerplants, o r systems t h a t would have affected the a i r c r a f t ' s performance before impact w i t h trees. There was no evidence o f a f i r e in flight. The crewmembers were q u a l i f i e d and c e r t i f i c a t e d . They received the t r a i n i n g prescribed i n the company t r a i n i n g programs, which were approved by the FAA. Both p i l o t s had received the crew r e s t period required by FAA regulations.

-

17

-

The thunderstorms which moved across the S t . Louis A i r p o r t and the surrounding area were severe. The s t o m were more intense i n a small area along the l o c a l i z e r caurse, where the accident occurred, than they were a t the a i r p o r t . '?.

.,

~.

w l barometric s e t t i n g s on the p i l o t ' s altimeters would have Theo caused the altimeters t o i n d i c a t e an a l t i t u d e lower than the actual a l t i t u d e o f the a i r c r a f t .

However, during v i b r a t i o n t e s t s , the p i n could n o t be removed, which indicates t h a t the p i n was probably displaced by impact. Although the first o f f i c e r made a number o f references t o a1t i t u d e during the approach, the f l i g h t c r e w d i d n o t mention a difference i n altitude indications between the two altimeters. A difference o f 500 f e e t would have been detected and challenged. F i n a l l y , no record o f a l t i m e t e r malfunction appeared on the a i r c r a f t f l i g h t logs. Therefore, a l t i m e t e r error was not a f a c t o r i n the accident.

- 18 The captain's f l i g h t d i r e c t o r system was believed t o be functioning properly u n t i l the case o f the f l i g h t d i r e c t o r instrument was dented, which locked the command bars i n a pitch-down display. The a i r c r a f t was i n a nosehigh a t t i t u d e about midway through the crash sequence. This conclusion i s supported by the captain's r e c o l l e c t i o n s and the impact damage t o the sycamore tree. Consequently, it i s possible t h a t the a t t i t u d e was near 200 , which caused the comand bars t o display a p i tch-down i n d i c a t i o n o f about loo

.

The f l i g h t was r o u t i n e u n t i l i t approached the S t . Louis terminal area. A t t h a t m i t e , the f l i g h t c r e w was aware t h a t thunderstorms which existed near the a i r p o r t might block the f l i g h t ' s approach. A f t e r receiving information "Quebec" on the ATIS, the f l i g h t c r e w would have expected t o receive radar vectors f o r an ILS approach t o runway 12R. Consequently, when the first o f f i c e r said, " I t ' s about 30 miles then from us, between us and the outer marker," and the captain replied, "About over the outer marker," they were t a l k i n g about a p r e c i p i t a t i o n r e t u r n (thunderstorm) displayed on the a i r c r a f t . weather radar, which indicated t h a t the storm was near the OM f o r runway 12R. M e d i a t e l y preceding these remarks, the flightcrew, i n a n t i c i p a t i o n o f an eastward movement o f the storm, apparently had elected t o f o l l o w the thunderstorm t o the a i r p o r t ( F i r s t O f f i c e r : 'I. I d o n ' t know, unless we f o l l o w i t i n bound." Captain: "Okay.!' F l r s t O f f i c e r : "That's Okay?" Captain: "Yeah" )

..

.

'

However. a f t e r the approach c o n t r o l l e r had informed the f l i g h t c r e w t h a t he would give them radar vectors f o r an ILS approach t o runway 30L. the captain apparently elected t o accept those vectors, b e l i e v i n g t h a t he would be able t o land a t the a i r p o r t i n f r o n t o f the thunderstorm. The captain continued the approach through the area o f thunderstorm c e l l s which were located south and southeast o f the a i r p o r t , and the a i r c r a f t emerged from the clouds about 6 miles southeast of the OM f o r runway 30L. The f l i g h t was e s s e n t i a l l y i n visual conditions from t h a t p o i n t u n t i l i t passed the OM, Shortly a f t e r passing the O M , the a i r c r a f t descended below the glidepath. The Board was n o t able t o determine the reason f o r the descent, b u t believes t h a t it was a r e s u l t o f strong downdrafts and severe thunderstorms near the l o c a l i z e r course. Witnesses' accounts o f the a i r c r a f t ' s behavior and an analysis o f the weather conditions support th.is b e l i e f . It i s also possible t h a t the captain descended i n order t o remain below clouds and t o maintain visual reference w i t h the ground as he continued the approach.

r

-

19

-

by the captain-of the a v a i l a b l e weather i n f o n a t i o n .

. .

The Board d i d not f i n d any conclusive evidence o f undue company pressure on p i l o t s t o adhere t o published f l i g h t schedules. Additionally, the captain denied t h a t such pressure would have affected h i s decision . t o continue the approach. The Board's review o f Ozark Air Line's t r a i n i n g program and company policies concerning thunderstorm avoidance and the operations manual indicated t h a t the material on thunderstorm avoidance was comprehensive with one, exception encounters w i t h thunderstorms i n the terminal area.

--

The manual stiDulated t h a t thunderstorms were t o be avoided bv 10 t o 20 miles depending on t h e i r severity. No exceptions were listd. The captain d i d n o t maintain 10- t o 20-mile separation from observed thunderstorms a f t e r coming under control o f the approach c o n t r o l l e r . However, Ozark management personnel and p i l o t s applied these provisions t o en route operations. I n terminal area operations the p i l o t should have evaluated the weather i n the terminal area, made a decision regarding h i s intentions, and kept ATC advised o f h i s i n t e n t i o n s so t h a t the c o n t r o l l e r could take appropriate action. I n t h i s instance, the p i l o t d i d evaluate the weather and decided t o continue t o accept the approach clearances issued by the controller. The Board believes t h a t more d e f i n i t i v e c r i t e r i a should be i n cluded i n the operations manual f o r operations i n the terminal area when thunderstorms e x i s t i n t h a t area. I n addition, more information regarding the low- altitude hazards associated w i t h thunderstorms should be provided t o the flightcrews. The captain o f F l i g h t 809 and other Ozark p i l o t s who t e s t i f i e d a t the public hearing d i d n o t appear t o be familiar w i t h p e r t i n e n t portions of the operations manual. The Board believes t h a t additional company emphasis i s required t o assure t h a t a l l p i l o t s are thoroughly f a m i l i a r with the company operating p o l i c i e s and procedures. There was an adequate amount o f weather information available t o the captain v i s u a l l y and through use o f the a i r c r a f t ' s weather radar. The fact t h a t the captain could see the runway l i g h t s through the r a i n may have misled him i n evaluating the i n t e n s i t y o f the thunderstorm. However, other cues regarding the i n t e n s i t y o f the storm should have been as v i s i b l e t o him as they were t o other p i l o t s on the approach.

These cues, w i t h h i s extensive p i l o t experience, should have been s u f f i c i e n t t o a l e r t him t o t h e p o s s i b i l i t y o f turbulence and downd r a f t s i n the v i c i n i t y o f the heavy r a i n and the r o l l cloud. An experienced p i l o t should have been aware o f the u p d r a f t and downdraft hazards associated w i t h r o l l clouds t h a t precede thunderstorm a c t i v i t y . These clouds are a d i r e c t i n d i c a t i o n o f the extreme s e v e r i t y o f the associated thunderstorm a c t i v i t y , and they should be avoided by a substantial distance. A d d i t i o n a l l y , the surface wind information and the heavy r a i n observation provided by the l o c a l c o n t r o l l e r should have a l e r t e d the captain t h a t he was continuing h i s approach i n t o d i f f i c u l t conditions. He was faced w i t h landing the a i r c r a f t i n heavy r a i n on a wet runway i n a strong crosswind. Considering these factors, the Board believes there were s u f f i c i e n t cues a v a i l a b l e t o the captain t o a l e r t him t o the p o s s i b i l i t y o f turbulence, downdrafts, and l i m i t e d v i s i b i l i t y i f he continued the approach through the r a i n area on the f i n a l approach. Because he could see the runeay through the r a i n the captain continued the approach i n t o the area of severe downdrafts and r e s t r i c t e d v i s i b i l i t y . Had the 'captain been b e t t e r i n f o m d regarding the hazards associated w i t h low-level turbulence i n thunderstorms, h i s decision might have been t o execute a missed approach and hold u n t i l the weather improved o r t o ' d i v e r t t o an a l t e r n a t e airport The captain's experience as a pilot-in-comnand was l i m i t e d . Although he was upgraded t o captain i n August 1971, he d i d n o t Perform d u t i e s as pilot-in-comnand u n t i l March 22, 1973. From March 22, t o the day Of the accident he flow about 66 hours as pilot-in-comnand of FH-227B aircraft.. About half of t h a t time was flown i n 23 days preceding the accident. The remainder was flown during t h e l a t t e r p a r t of March and e a r l y A p r i l 1973. The captain's opportunity t o develop the judgment required t o make an appropriate decision i n the circumstances he faced on t h i s f l i g h t was l i m i t e d t o h i s experience as a first O f f i c e r .

.

--

Weather Analysis The captain derived v i r t u a l l y a l l h i s information about the l o c a t i o n and s e v e r i t y o f the thunderstorm a c t i v i t y from visual observations and the airborne weather radar. The area and terminal a v i a t i o n weather forecasts d i d n o t provide s i g n i f i c a n t informati.on about the l o c a t i o n o r s e v e r i t y o f the storms. The n a r r a t i v e radar sumnary issued a t 1640 and the a v i a t i o n terminal forecast f o r S t . Louis are d i f f i c u l t t o reconcile. The l a t t e r , lssued a t 1140, remained unchanged u n t i l 1740, which was s h o r t l y before the accident. It predicted nothing worse than occasional c e i l i n g s o f 3,000 feet overcast, w i t h 6-mile v i s i b i l i t y i n thunderstorm and moderate r a i n showers. This forecast should have been amended t o r e f l e c t the conditions i d e n t i f i e d i n the radar summaries. I f the forecasts were amended, the a v i a t i o n community would l i k e l y have been a l e r t e d t o the p o t e n t i a l s e v e r i t y o f the thunderstorms t h a t were moving i n t o the area from. the west and south.

- 21 -

Additionally, it i s d i f f i c u l t t o reconcile the NWS's f a i l u r e t o issue

Severe weather warnings mean more t o a p i l o t than j u s t a warning potential hazards. They also stimulate him t o t h i n k o f a l t e r n a t i v e rses o f a c t i o n i f severe conditions materialize. Also, such warnings confirm'what the p i l o t suspects b u t i s unable t o v e r i f y , because equipment l i m i t a t i o n s , cockpit workload, h i s p o s i t i o n r e l a t i v e t o severe weather, and e x i s t i n g f l i g h t conditions. To be e f f e c t i v e , ever, these-warnings must be timely.

,

The weather radar sumnary charts issued a t 1640 and 1740 by the NSSFC a t Kansas City showed scattered thunderstorm a c t i v i t y i n the St. Louis area. However, l o c a l weather radar sumnaries showed moderate t o severe a c t i v i t y from 40 t o 60 miles west o f S t . Louis as e a r l y as 1530. The severe a c t i v i t y was moving eastward a t 20 knots. The Board was unable t o determine why the NSSFC had f a i l e d t o locate and i d e n t i f y the thunderstorm a c t i v i t y near S t . Louis, except t h a t e a r l i e r i n the day, the NSSFC had determined t h a t a l l the meteorological conditions required for severe thunderstorm a c t i v i t y d i d n o t e x i s t . The Ozark f l i g h t dispatch center a t S t . Louis had l i t t l e o f f i c i a l

patch center t o expect thunderstorm a c t i v i t y i n the imnediate area. Also, the f l i g h t dispatch center should have t r i e d t o determine more precisely the l o c a t i o n and s e v e r i t y o f the thunderstorm a c t i v i t y . Such an endeavor, however, was n o t made u n t i l s h o r t l y before the thunderstorms moved across the a i r p o r t . By then, i n s u f f i c i e n t m ti e remained f o r the dispatcher t o warn F l i g h t 809.

'.~

severe thunderstorm warning. The Board believes t h a t the information contained i n these sumnaries should have received wider dissemination, because i t was t h e best analysis o f the l o c a l weather s i t u a t i o n .

- 22 As a r e s u l t o f t h i s and several other accidents which have occurred during thunderstorms i n terminal areas, the question arises whether FAA c o n t r o l l e r s should be authorized t o refuse p i l o t s ' r e quests f o r an approach, landing, o r takeoff, when the weather conditions a t the a i r p o r t are too severe, i n the c o n t r o l l e r ' s opinion, for safe terminal area operations. (See Appendix F. ) Under e x i s t i n g procedures, c o n t r o l l e r s may provide only o f f i c i a l weather data, general observations without s p e c i f i c values, and i n f o r mation derived from instruments, radar, o r p i l o t reports, which i s generally adequate under most circumstances. However, when the c o n t r o l l e r i s able t o observe severe weather a c t i v i t y a f f e c t i n g the a i r p o r t o r the approach o r departure paths, the Board believes t h a t he should .have a u t h o r i t y t o refuse approach, landing, and t a k e o f f requests except upon the declaration o f an emergency by the p i l o t .

--

Survivability The accident was nonsurvivable w i t h respect t o the passengers because the decelerative forces approached the l i m i t s o f human tolerance, the r e s t r a i n t mechanisms f a i l e d , and the occupiable area d i d n o t remain i n t a c t . The f a t a l and nonfatal i n j u r i e s a l i k e indicated t h a t the decelerative forces had been near the l i m i t s o f human tolerance. A ll but one o f the passenger seats f a i l e d during the crash sequence. The passenger cabin was t o r n open by impact w i t h trees, and the unrestrained occupants were ejected w i t h s u f f i c i e n t force t o produce f a t a l i n j u r i e s upon c o l l i s i o n w i t h unyielding objects. Four passengers survived because they were thrown clear, without c o l l i d i n g w i t h any objects t h a t could i n f l i c t more serious i n j u r i e s . Both and t h e i r ficantly, had t h e i r

p i l o t s survived because the cockpit remained r e l a t i v e l y i n t a c t r e s t r a i n t mechanisms (seats and seatbelts) d i d n o t f a i l . Signiboth p i l o t s probably would have received only minor i n j u r i e s , upper torsos been restrained by shoulder harnesses.

The cabin attendant received f a t a l i n j u r i e s when she was struck by cargo a f t e r the f a i l u r e o f the a f t cargo compartment r e s t r a i n t net. The f a i l u r e indicated t h a t the decelerative forces were q u i t e high i n the a f t section o f the a i r c r a f t . The rescue was conducted i n a timely and f a i r l y o r d e r l y fashion. I n i t i a l l y , because o f a l a c k o f centralized control, more f i r e and p o l i c e u n i t s responded than were needed. Although the presence o f too many people and the adverse weather conditions probably contributed some confusion, the speed w i t h which the rescue was accomplished was n o t a f a c t o r i n the s u r v i v a b i l i t y o f the accident. However, the Board's experience indicates t h a t i n the event o f an accident i n v o l v i n g a s u b s t a n t i a l l y higher number of i n j u r i e s , a more coordinated response i s required t o care f o r survivors

- 23 .2 Conclusions

1.

The accident was nonsurvivable.

2.

The cabin attendant's seat was n o t properly c e r t i f i c a t e d , because i t d i d n o t meet FAA regulations.

3.

The captain's and f i r s t o f f i c e r ' s i n j u r i e s would have been much less severe, had these crewmenhers been restrained by shoulder harnesses.

4.

The thunderstorm t h a t moved across the a i r p o r t and the l o c a l i z e r course s h o r t l y a f t e r 1740 was severe; the storm was more severe i n a small area along the l o c a l i z e r course where the accident occurred.

5.

The s e v e r i t y o f the storm was n o t r e f l e c t e d i n the o f f i c i a l NWS weather data available t o the flightcrew, company dispatchers, o r a i r t r a f f i c c o n t r o l l e r s .

6.

The NWS a v i a t i o n terminal forecast v a l i d a t the time o f the accident f o r S t . Louis d i d n o t p r e d i c t accurately the weather conditions t h a t could have been expected t o a f f e c t the area, and an amended forecast was n o t issued.

7.

The NUS n a r r a t i v e radar sumnaries accurately r e f l e c t e d the weather conditions moving i n t o the S t . Louis area.

8.

The n a r r a t i v e weather radar sumnaries were not available t o e i t h e r the FAA a i r t r a f f i c control f a c i l i t i e s , the Ozark Air Lines F l i g h t Dispatch Center, o r the f l i g h t c r e w .

9.

Orark Air Lines d i d n o t provide i t s flightcrews w i t h s p e c i f i c thunderstorm avoidance c r i t e r i a f o r terminal area operations.

10.

The airborne weather radar on N4215 functioned properly, and the f l i g h t c r e w used the radar t o locate the thunderstorms i n the S t . Louis area.

11.

Between the OM and the accident s i t e , the a i r c r a f t was struck by one o r more b o l t s o f l i g h t n i n g .

12.

There was no evidence t h a t l i g h t n i n g adversely a f f e c t e d any o f the v i t a l systems o r components o f the a i r c r a f t .

- 24 -

14.

(b)

The captain decided t o continue h i s approach i n t o weather conditions associated w i t h a ' thunderstorm; the s e v e r i t y o f these conditions should have been apparent t o him.

Probable. Cause

The National Transportation Safety Board determines t h a t the probable cause o f the accident was t h e a i r c r a f t ' s encounter w i t h a downdraft following the captain's decision t o i n i t i a t e and continue an instrument approach i n t o a thunderstorm. The captain's decision probably was i n fluenced by the lack o f a t i m e l y issuance o f a severe weather warning by the National Weather Service, and the improper assessment o f the weather conditions i n the terminal area by the f l i g h t c r e w and the f l i g h t dispatcher. 3. RECOMMENDATIONS The Safety Board made three recomnendations (A-73-66 and A-73-105 and 106) t o the Federal Aviation Administration on September 6 , 1973, and October 25, 1973, respectively. These recommendations involved the cabin attendant's seat i n F-27 and FH-227 a i r c r a f t and the a d d i t i o n o f crewmember shoulder harnesses i n a l l transport category a i r c r a f t t h a t were c e r t i f i c a t e d before January 1, 1958. The Safety Board made three additional recommendations (A-74-12, 13, and 14) on A p r i l 18, 1974. These recomnendations involved r e v i s i o n of a i r t r a f f i c control procedures i n the terminal area, new a i r t r a f f i c cont r o l radar for terminal areas, and a system t o improve the dissemination o f severe weather information. (See Appendix F.)

i

- 25 BY THE NATIONAL TRANSPORTATION SAFETY BOARD

Is1

.-*, *t

..,,

JOHN

H.

REED

Chai man

/SI

FRANCIS H . McADAMS henber

JsJ

LOUIS M. THAYER Member

JsJ

ISABEL A. BURGESS Member

Is1

WILLIAM R . HALEY Member

- 27 Appendix A INVESTIGATION AND HEARING

. .Investigation vestigative groups f o r operations, a i r t r a f f i c control , witnesses, ather, human f a c t o r s , structures, powerplants , systems , maintenance cords, f l i g h t data recorder, and cockpit voice recorder. Representatives o f the Federal Aviation Administration, Ozark Air

.

Hearing and Deposition

A 3-day p u b l i c hearing was held i n the Sheraton Jefferson Hotel, St. Louis, Missouri, beginning August 28, 1973.

- 28 -

I

Appendix B

AIRMAN INFORMATION Captain A r v i d L. Linke Captain Linke, 37. has been employed by Ozark Air Lines since A p r i l 1, 1965. He holds A i r l i n e Transport P i l o t C e r t i f i c a t e No. 1349358, w i t h a type r a t i n g i n FH-227 a i r c r a f t . He was advanced from f i r s t o f f i c e r t o captain i n August 1971, b u t d i d n o t assume comnand r e s p o n s i b i l i t i e s u n t i l he received h i s captain's checkout i n the FH-227 on March 22, 1973. He successfully completed a p r o f i c i e n c y check i n the FH-227 on March 19, 1973, and a recurrent ground t r a i n i n g on March 16, 1973. He was l a s t issued a f i r s t - c l a s s medical c e r t i f i c a t e , without l i m i t a t i o n s , on February 14, 1973. During h i s f l y i n g career, Captain Linke has accumulated 9,170:05 hours o f f l y i n g time, o f which 4,382:03 hours were flown i n F-27 and FH-227 a i r c r a f t . He has flown 65:55 hours as pilot-in-comnand o f FH-227, and during the 30-day period preceding the accident, he flew 30:25 hours.

F i r s t O f f i c e r Michael D. Williams F i r s t O f f i c e r Williams, 28, was employed by Ozark Air Lines on January 31, 1972. He holds Air1i n e Transport P i ~ l o tC e r t i f i c a t e No. 1744164 w i t h a type r a t i n g i n DC-3 a i r c r a f t . : . He also has a f l i g h t i n s t r u c t o r c e r t i f i c a t e f o r airplane and instruments. He passed h i s i n i t i a l second-in-conand check on February 26, 1972, h i s l a s t l i n e check on J u l y 14, 1972, and h i s l a s t second-in-conand check on December 28, 1972. He was l a s t issued a f i r s t - c l a s s medical c e r t i f i c a t e , without l i m i t a t i o n s , on December 13, 1972. F i r s t O f f i c e r Williams has accumulated about 3,921 hours o f f l y i n g time during h i s career t o the date o f the accident. He has flown about 989 hours i n the FH-227, o f which 59.5 hours were flown i n the 30-day period preceding the accident. Cabin Attendant Beth A. Williams Cabin attendant Williams, 23, was employed by Ozark Air Lines on J u l y 13, 1970. She completed cabin attendant t r a i n i n g on August 7, 1970. She passed a check-ride i n the FH-227 on March 19, 1973. Her l a s t recurrent t r a i n i n g i n FH-227 and DC-9 a i r c r a f t was completed on July 4, 1973.

Appendix C AIRCRAFT INFORMATION Aircraft N4215, an FH-227B, was manufactured by the Fairchild-

The aircraft total time i n service and the time since overhaul

The No. 1 propeller had a total time of 10,936 hours, including 236 hours since overhaul. The No. 2 propeller had a total time of ,785 hours, including 4,890 since overhaul. All airworthiness directives and service bulletins on the a i r c r a f t d powerplants were complied w i t h .

-

31

-

APPENDIX E tional Weather Service Radar Photos 1 of 2. 1715 CDT, July 23, 1973. ge 50 NM. Hatch marks represent approximate area where ground cluttex urn can be expected.

-

32

-

Appendix E National Weather Service Radar Photos 2 of 2. 1744 CDT, July 23, 1973. Range 50 NM. Hatch marks represent approximate area where ground clutter return can be expected.

DEPARTMENT OF TRANSPORTATION FEDERAL AVIATION ADMINISTRATION

-

33

-

SEP 19 1973 Honorable John H. Reed Chairman, National Transportation Safety Board Department o f Transportation Washington, O.C. 20B1

Dear John: This r e p l i e s to your Safety Recornnerdation A-73-66 requesting the use o f a l l f l i g h t attendant seats i n F-27 and FH-227 a i r c r a f t be prohibited u n t i l modifications are accomplished. There are many d i f f e r e n t seat designs. locations and positions o f the f g i lh t attendant i n t h i s series o f airplanes. I n maw a i r l i n e configurations, the attendant occupies a s p e c i f i c passenger seat designated exclusively f o r the attendant. This seat does n o t resenble the seats you mentioned on M a w k and Ozark Airlines' airplanes. Due to these differences. we have assessed these s e a t s on an i n d i v i d u a l basis. Our AD 72-7-12 d e a l t w h ti the Mohawk A i r l i n e s it e o f issuance. was the only seat considered i n s t a l l a t i o n which, a t them hazardous due to i t s p a r t i c u l a r location.

W h ti respect t o p r o h i b i t i n g f u r t h e r use o f the seat i n s t a l l e d on Ozark's FH-227B airplanes, action along these l i n e s began a month prior t o the accident i n St. Louis, Missouri. We were advised on August 20 t h a t Ozark i s i n i t i a t i n g action to relocate the fli#t attendant to a forward f a c i n g type seat i n the rear o f the cabin. The new l o c a t i o n and seat configuration w l i be subject to FAA evaluation h ti a l l requtrements. As an i n t e r i m action. a n o t i c e f o r conpliance w was issued by Ozark, e f f e c t i v e August 27, t o require f l i @ t attendants t o occupy the r e a r m s t passenger seat. on the l e f t side, a t the aisle. u n t i l f i n a l seat r e l o c a t i o n modifications are accomplished. We believe the present Ozark i n t e r i m seat l o c a t i o n and f i n a l seat location, both o f which are presently used by other a i r l i n e s f o r l i meet the objective o f your recom locating t h e i r attendants. w inendation as i t applies to the Ozark configuration. This type o f passenger-cargo conbination does n o t e x i s t amng other domestic a i r c a r r i e r operators o f the F-27 and FH-227 airplanes. Sincerely,

WASHINGTON,

D.C.

Adopted by the NATIONAL TRANSPORTATION SAFETY BOARD a t i t s o f f i c e i n Washington, D. C . on the 22nd day o f August 1973

FORWARDED TO:

1

Honorable Alexander P. Butterfield )

After the Mohawk Airllnes FH-227B accident at Albany, New York, on March 3, 1972, the Federal Aviation Administration issued an Airworthiness Mrective prohibiting the further use of the aft-facing stewardess' crew seat mwnted against the lavatory wall i n all F-27 and FK-227 a i r c r a f t . This prohibition wa6 t o continue i n effect u n t i l the seat was m o d i f i e d t o comply with t h e provisions of section 4b.358 of the C i v i l Aeronautics

Manual (CAM). The prohibition against use of the f l i g h t attendant seat was made because the proximity of the occupant's head t o the entry door actuating mechanism did not conform t o the provisions of CAM &.358(b). This provision s t a t e s that passengers and crew shall be afforded protection from head injuries by one of the following means:

1

j

1. Safety b e l t and shoulder harness.

2. Safety b e l t and elimination of a l l injurious objects within striking radius of the head.

3. Safety b e l t and a cushioned r e s t which will support

arms, shoulders, head, and spine.

Additionally, the proximity and orientation of the carry-on luggage rack directly opposite t h i s f l i g h t attendant seat was cited i n the Airworthiness Mrective.

?

-

35 Honorable Alexander P. Butterfield (2)

Appendix F

During our investigation of the recent accident involving an Ozark A i r Lines FH-221 at S t . Louis, Missouri, our investigators examined the flight attendant crew seat attached t o the aft galley structure next t o the cargo loading door. Because of the many similarities with respect t o the impact parameters of this and the previously mentioned ”Mohawk” accident, they assessed the hazard potential of this seat as compared t o the previous seat i n s t a l l a t i o n which had been restricted. I n our view, the Ozark installation aoes not conform t o the provisions of CAM 4b.358 i n that the occupant‘s head i s 18 inches from the actuating mechanism and upper t r a c k of the cargo door. Moreover, there i s no protective padding provided at this location. The flight attendant station i s not equipped with a shoulder harness. There are no cushioned supports f o r the shoulders or head which might prevent lateral movement. Also, the seat location i s directly opposite the passage t o the cargo compartment. Although this passageway i s blocked by cargo netting, the openings i n the netting are large enough (8 inches by 8 inches) t o allow smaller cargo parcels t o pass through. Additionally, the top of this netting is located approximately 8 t o 11 inches from the ceiling, allowing passage of a r t i c l e s i n turbulence or emergency conditions.

finally, the design of this f l i g h t attendant seat is such that, i n our view, it does not meet the requirements of CAM 4b.362(g) and CAM 4b.362-6(a). The seat pan folds downward against the bulkhead i n the stared position. When i n use, the seat i s supported by an over-center retraction mechanism and a bar, which i s attached t o the side of the seat pan with a keyhole arrangement. I n this position, the seat reduces the passageway width of the cargo door e x i t t o 12 inches. The semipermanent support of this flight attendant seat, therefore, i s not i n conformance with FAA policy as it applies t o CAM 4b.362(g), since it is not springloaded f o r automatic retraction when the seat i s vacated t o allow a 20-inch passageway leading t o this exit. I n view of the above, the National Transportation Safety Board reccaumends that the Federal Aviation Aaministration: Issue an inmediate Airworthiness Directive prohibiting the use of a l l f l i g h t attendant seats i n F-27 and FH-227 a i r c r a f t until these stations are modified t o comply with the applicable regulations. McAdamS, Thayer, and Haley, Members, concurred i n the above reccnmnendations. Reed, Chairman, and Burgess, Member, were absent, not voting.

By:

John H. Reed Chairman

NATIONAL TRANSPORTATION SAFETY BOARD

Honorabile

WASHINGTON, DL. I n 1

Jtr7y

ISSUED:

October 25, 1973

Adopted by the NATIONAL TRANSPORTATION SAFETY BOARD a t i t s o f f i c e i n Washington, 0. C. on the 10th day o f October 1973

2-33

i njuries. serious h The capts control I The requiremt

Federal J aircraft accident i n these provisio

In Board re SAFETY RECOMMENDATIONS A-73-105 & 106 A significant advance toward improved crew protection has been made by recent rulemaking requirements that crewmembers of transport-category a i r c r a f t operating under 14 CFFi 121 wear t h e i r shoulder harnesses during takeoff and landing. Similarly, the recently issued Notice of Proposed Rule Making 73-1, “Crashworthiness of Small Airplanes,” proposes t o provide f o r the i n s t a l l a t i o n and use of shoulder harnesses f o r occupants of small airplanes. The provisions of t h i s NPRM will afford a significant amount of additional protection t o v i r t u a l l y the e n t i r e aviation population.

m e National Transportation Safety Board i s encouraged by these steps, which are positive indications of the increased emphasis being placed on accident survivability. However, the Board believes that further Consideration is merited f o r including i n these shoulder-harness provisions the following two categories of aircraft: rans sport Category Aircraft Certificated Prior t o 1958

I n a l e t t e r dated January 29, 1973, t o the Administrator, Federal Aviation Administration, the Safety Board stated that Part 121 should be amended t o require t h a t all transport-category a i r c r a f t be equipped with shoulder harnesses a f t e r a reasonable date i n order t o encompass all a i r commerce segments, regardless of the type of equipment flm. We expressed t h i s opinion in light of tbe findings made during the investigation of a Mohawk Airlines FH-227 which crashed i n t o a residence a t Albany, New YOrk, on March 3, 1972, killing 14 passengers as well as the 2 crewmembers i n the cockpit. The Safety Board’s investigation revealed t h a t both p i l o t s probably could have survived if they had worn shoulder harnesses. Expert medical testimony corroborated our findings.

Corpora.

ou -rove the pra shoulde corpore o r pro1 operatj requirt not na

for, tl aircra: 0 Ypsila both c belts

that 8 aPPue also k the CI

Honorable Alexander P. Butterfield

37

-

Appendix F

- 2

,

In the recent Ozark FH-227 accident at St. Louis Missouri, on July 23, 1973, both p i l o t s survived the accident but s f l e r e d serious injuries. Our investigation-revealed that the copilot received a psnel. serious head injury because he was thrown against the inst-nt The captain sustained several r i b fractures when he w88 thrown into the control wheel. He also received serious head injuries.

FE-227 is now

exempted by 14 CFR 121 from the shoulder-harness requirement since it was type certificated prior t o January 1, 1958. Federal Aviation Administration s t a t i s t i c s show that approximately 268 a i r c r a f t are s t i l l i n use which are so exempted. The recent Ozark accident not only reemphasizes the need f o r shoulderharness protection i n these a i r c r a f t but a l s o focuses attention on the less stringent safety provisions f o r p i l o t s who fly older equipment. !The

,

In light of t h i s discussion, the National Transportation Safety Board recomuends that the Federal Aviation Administration: Amend 14 CFR 121 t o require that all transport-category a i r c r a f t certificated prior t o January 1, 1958, be equipped with shoulder harnesses at each crew station, after a reasonable date, t o allow operators t o r e t r o f i t their equipment. Corporate/Executive Aircraft Our review of the impact of FAA's recent rulemaking action t o @ r o v ethe safety of flightcrews disclosed that with implementation of the provisions of NHlM 73-1, v i r t u a l l y all p i l o t s w i l l benefit from shoulder-harness protection with the exception of p i l o t s who f l y large corporate and executive a i r c r a f t . The Board i s not ware of any existing o r proposed requirement f o r shoulder harnesses for this class of a i r c r e f t operating under the rules of 14 CFR 91. Specifically, although 14 CFR 25 requires provisions f o r shoulder harnesses i n such a i r c r a f t , Part 91does not now require, and the proposed changes of NPRM 73-1 would not provide for, the i n s t a l l a t i o n of such r e s t r a i n t i n large corporate and executive aircraft.

On February 21, 1973, a bar J e t crashed at Willow Run Airport, Ypsilanti, Michigan. Although the cockpit remained structurally intact, both crewmembers died as a result of loss of r e s t r a i n t when t h e i r seatbelts failed at the outboard attach points. Our investigation disclosed that shoulder harnesses not o n l y would have redistributed the forces applied t o the seatbelts, thereby reducing the possibility of failure, but also would have prevented violent upper torso movement, thereby alleviating the crewmembers' injuries.

- 36 -

Appendix P

Honorable Alexander P. Butterfield

-3-

I n order t o provide increased protection f o r crewmembers, and t o avoid a potential inconsistency i n the regulations, the Safety Board believes t h a t steps should be taken t o require the installation of shoulder harnesses i n large corporate and executive a i r c r a f t . Accordingly, the National !Cransportation Safety Board recommends that the Federal Aviation Administration:

--_For\

Amend 14 CFR 91 t o require the installation of shoulder harnesses a t f l i g h t deck stations on large a i r c r a f t which operate under this

part.

REED, Chairman, M c D !IAhS,T A IYER, and

the above recommendations.

fIAtEY, Habers, concurred i n BUIEGESS, Itember, was absent, not voting.

Hon A& Fed

Was

--01

Chairman

was in.

hanspl

three

~

F

at St. the t h final

the IC the cc the we

interc deem 1 approt over

1

clear or t h use o contr

- 39 Appendix F NATIONAL TRANSPORTATION SAFETY BOARD WASHINGTON, D.C.

........................................ Forwarded t o :

Honorable Alexander P. B u t t e r f i e l d Administrator Federal Aviation Administration Washington, D. C. 20591

SAFETY RECOMMENDAT ION (S)

A-74-22 thru 14

On J u l y 23, 1973, an Ozark A i r l i n e s Fairchild Hiller FH-22773 Was involved i n an accident a t St. Louis, Missouri. The National Transportation Safety Board's investigation of t h e accident revealed three safety items which warrant corrective action.

First, u n t i l j u s t before the accident, air traffic c o n t r o l l e r s a t S t . Louis issued clearances for approaches and.landings, despite t h e thunderstorms which were over the i n i t i a l approach path, t h e final. approach path, and t h e a i r p o r t . Inmediately before the accident, the l o c a l c o n t r o l l e r stopped issuing departure clearances. Althmgh the c o n t r o l l e r d i d n o t have a u t h o r i t y t o s t o p departures because of the weather, the Safety Board believes that he acted i n the best i n t e r e s t of safety. It further believes that, i n conditions they deem hazardous, c o n t r o l l e r s should be given the a u t h o r i t y t o deny (1) approach and landing clearances when thunderstorm a c t i v i t y e x i s t s over either the approach path or the a i r p o r t and (2) departure clearances when thunderstorm a c t i v i t y exists over eLther the a i r p o r t or t h e departure path. This new a u t h o r i t y would make more effective use of the wealth of terminal weather information available t o the controller, s p e c i f i c a l l y :

a.

His d i r e c t and continuing visual observation of l o c a l atmospheric conditions and associated a i r c r a f t behavior.

b.

H i s r e c e i p t and evaluation of p i l o t reports (PIREP'S) regarding f l i g h t conditione i n the terminal area.

c.

The informative capacity of ground-based radar.

a.

The direct links f o r transmission of terminal weather r e p o r t s between the National Weather Service and ATC.

Appendix F

- 40

Honorable Alexander P. B u t t e r f i e l d

(2)

Honorable I

Since 1963, accidents i n which thunderstorm a c t i v i t y yas a f a c t o r have caused over 100 deaths, 40 serious i n j u r i e s , and millions of d o l l a r s i n property damage. Among these accidents are the following: American Airlines, Knoxville, Tenn., 1962 Mohawk Airlines, Rochester, N.Y., 1963 American Airlines, New York, N.Y., 1964 DH-125, Paducah, Ky., 1966 Gnnnman TBM, Elko, Nev., 1966 Lockheed PV-1, Philadelphia, 1971 Eastern A i r Lines, lauderdale, Fla., 1972 National Airlines, New &leans, la,, 1972 Convair 990, Agana, Guam, 1973

Ft.

Pa.,

Second, j u s t before t h e accident i n St. Louis, through the use of radar incapable of displaying d i f f e r e n t l e v e l s of p r e c i p i t a t i o n echo i n t e n s i t y , c o n t r o l l e r s vectored several a i r c r a f t through a s o l i d s q u a l l l i n e which contained severe thunderstorm and tornado a c t i v i t y . The c o n t r o l l e r s vectored the a i r c r a f t through the narrowest portion of t h e p r e c i p i t a t i o n echo pattern displayed on the radarscope i n order t o g e t the a i r c r a f t t o a f i n a l approach c m s e . I n our opinion, t h i s was a very dangerous practice because the c o n t r o l l e r ' s radarscope display d i d not indicate whether the l i n e of echoes contained a severe thunderstom o r tornado. The Safety Board believes t h a t radar capable of locating severe weather and displaying convective turbulence should be developed for and used i n the terminal areas. Third, t h e Safety Board learned that t h e tower and apiproach control f a c i l i t y a t St. Louis has no system by which t o r e l a y severe thunderstorm warning b u l l e t i n s t o inbound and outbound f l i g h t s when the terminal area i s included i n such b u l l e t i n s . The lack of such a system was not a f a c t o r i n t h i s accident, because t h e severe thunderstorm warning b u l l e t i n which had been issued about 3 minutes before the accident by the National Weather Service, was not relayed t o the tower and approach control until after the accident. Nevestheless, t h e Safety Board believes that t h e information contained i n these b u l l e t i n s i s v i t a l t o every p i l o t who must decide whether t o f l y i n t o or out of a terminal area which is affected by thunderstom a c t i v i t y . We a l s o believe that these b u l l e t i n s should be relayed expeditiously. Accordingly, t h e National Transportation Safety Board recornends

that the Federal Aviation Administration: 1. Revise terminal air t r a f f i c control procedures t o authorize controllers, when they deem an operational hazard is present, t o deny (1) approach and landing clearances when thunderstorm

i

2.

3.

Mem' f o r cons FiEE concurre

-

41 -

Honorable Alexander P. Butterfield

Appendix F

(3)

a c t i v i t y exists over e i t h e r t h e approach path or t h e a i r p o r t , and ( 2 ) takeoff clearances when thunderstorm a c t i v i t y exists over e i t h e r t h e a i r p o r t o r t h e departure path. 2.

Develop and i n s t a l l terminal air t r a f f i c control radar capable of locating severe weather and displaying convective turbulence. This radar should be used t o vector a i r c r a f t around severe weather.

3.

Implement, i n cooperation w i t h t h e National Weather Service, a system t o r e l a y severe thunderstorm and tornado warning b u l l e t i n s expeditiously t o inbound and outbound f l i g h t s when such b u l l e t i n s include the terminal area.

Members of our Bureau of Aviation Safety will be available f o r consultation i f desired. REED, Chairman, M c A D W S , T H A Y E R , m E S S , and concurred i n the above recammendations.

HALFY, Members,

By :c(John H. Reed Chairman

GPO

877.725