REPUBLIC OF KENYA
MINISTRY OF TRANSPORT
CIVIL AIRCRAFT ACCIDENT REPORT
CAV/ACC /8/99
REGISTRATION MARK:
N733YU
AIRCRAFT TYPE:
CESSNA TU 206 G
OPERATOR/OWNER:
AFRICAN INLAND MISSION INTERNATIONAL
(AIM) AIR SERVICES.
LOCATION:
NGEI ESTATE, NAIROBI ON APPROACH TO
WILSON AIRPORT RUNWAY 07.
DATE:
26TH AUGUST 1999
TIME:
1042 HOURS
ALL TIMES IN THIS REPORT ARE UTC
ACCIDENT INVESTIGATION BRANCH
P.O. BOX 52692 NAIROBI
TELEPHONE: 254-20-2729200
FAX: 254-20-2737320
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1
2
3
4
FACTUAL INFORMATION ................................................................................................. 5
1.1.
HISTORY OF THE FLIGHT ....................................................................................... 5
1.2.
INJURIES TO PERSONS ........................................................................................... 6
1.3.
DAMAGE TO AIRCRAFT ........................................................................................... 6
1.4.
OTHER DAMAGE ........................................................................................................ 7
1.5.
PERSONNEL INFORMATION .................................................................................. 8
1.6.
AIRCRAFT INFORMATION ....................................................................................... 9
1.7.
METEOROLOGICAL INFORMATION ..................................................................... 9
1.8.
AIDS TO NAVIGATION .............................................................................................. 9
1.9.
COMMUNICATION .................................................................................................... 10
1.10.
AERODROME ........................................................................................................ 10
1.11.
FLIGHT RECORDERS ......................................................................................... 10
1.12.
WRECKAGE AND IMPACT INFORMATION .................................................... 11
1.13.
MEDICAL AND PATHOLOGICAL INFORMATION ......................................... 11
1.14.
FIRE ......................................................................................................................... 11
1.15.
SURVIVAL .............................................................................................................. 11
1.16.
TEST AND RESEARCH ....................................................................................... 12
1.17.
ADDITIONAL INFORMATION ............................................................................. 12
1.18.
NEW INVESTIGATION TECHNIQUES .............................................................. 12
ANALYSIS........................................................................................................................... 13
2.1.
CIRCUMSTANCES.................................................................................................... 13
2.2.
LOADING .................................................................................................................... 14
CONCLUSION.................................................................................................................... 15
3.1.
FINDINGS ................................................................................................................... 15
3.2.
PROBABLE CAUSE ................................................................................................. 15
SAFETY RECOMMENDATIONS .................................................................................... 17
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SYNOPSIS
The accident to Cessna TU 206 G registered N733YU, was notified to the
Accident Investigation Branch at 1055 hrs on 26 th August 1999 by Nairobi’s
Wilson Airport Control Tower. At 1300 hrs field investigations began.
The National Transportation Safety Board of the USA was informed of the
accident. The aircraft operator/owner was African Inland Mission International
(AIM) Air Services based at Wilson Airport, Nairobi.
When aircraft was on approach to Wilson Airport on a flight from Mwanza
Airport, Tanzania, the pilot reported to Nairobi Wilson Air Traffic Control (ATC)
that he had an engine problem. Shortly thereafter, the aircraft crashed into a
one storey building adjacent to the flight path as it approached Runway 07.
Both the aircraft and building were extensively damaged. There was one
fatality, three serious and one minor injury.
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1 FACTUAL INFORMATION
1.1. HISTORY OF THE FLIGHT
On August 26th 1999, the Cessna TU 206 G aircraft departed Wilson
Airport, Nairobi in the morning for Mwanza Airport, Tanzania and was to
return to Wilson on the same day. The flight to Mwanza was uneventful.
The aircraft took-off from Mwanza on a Visual Flight Rules (VFR) flight at
0915 hrs with five persons on board and fuel endurance of four (4) hours.
The Estimated Time of Arrival (ETA) at the final approach point to Wilson
Airport (normally called “Monastery”) was 1041 hrs, landing Wilson at 1043
hrs. A Company aircraft had departed a few minutes ahead of the accident
aircraft from Mwanza to Wilson flying on the same route and on a VFR
flight.
The aircraft contacted Wilson Airport Control Tower at 1023 hrs and was
instructed to report at the “Monastery” for landing Runway 07. The revised
ETA for Wilson was 1041 hrs as reported by the pilot.
The aircraft reported “Monastery” and commenced the final approach to
Runway 07. Air Traffic Control cleared the aircraft to report next at short
final (normally position called “Army Camp”). After reporting overhead
“Army Camp”, the pilot reported to have experienced a power loss. The
aircraft was seen by the Tower veering to the left of extended centerline
and descending over a residential area. It went through some branches of
a gum tree on the descent path before finally crashing into a one storey
building located beyond a school football pitch. A trailing aircraft pilot saw
the accident aircraft making side to side maneuver as it descended into the
residential area.
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Immediately, ATC advised the Wilson Airport Crash Fire Services to
proceed to the accident site. A passenger who was seated on the front
seat was fatally injured while the pilot and two passengers were seriously
injured. One passenger received minor injuries.
1.2. INJURIES TO PERSONS
INJURIES
CREW
PASSENGERS
OTHERS
FATAL
-
1
-
SERIOUS
1
2
-
MINOR / NONE
-
1
-
1.3. DAMAGE TO AIRCRAFT
The aircraft descended at a high forward speed in a fairly steep nose-down
attitude and crashed past balcony of a one-storey residential building. The
impact made the aircraft break through the house wall and was completely
destroyed.
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1.4. OTHER DAMAGE
The roof and the wall including all household items in the top floor of the
residential house were extensively damaged. Nobody in the building was
injured.
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1.5. PERSONNEL INFORMATION
The pilot was a male adult aged thirty-eight (38) years. He was a
holder of Federal Aviation Authority (FAA) Airline Transport Licence
number 344762424 issued on 27th June 1997. He also had a Kenya
Commercial Pilot licence number YK 44 26 CL issued on 10th May
1999, valid to 22nd April 2001 based on the strength of the FAA
licence.
The pilot was licenced to fly Cessna 206 and 210 aircraft. At the time
of accident, he had a total of 1632.5 hours of which 283.8 hours were
on the Cessna 206 type. In the last 28 days and 90 days he had
flown a total of 16.8 hrs and 60.2 hours respectively. The crew rest
period was in accordance with the approved flight operations manual
requirements.
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1.6. AIRCRAFT INFORMATION
The aircraft registered N733YU was manufactured by Cessna Aircraft
Company of Wichita Kansas in the USA in 1979 under construction
serial number U20604810. The aircraft had valid certificates of
registration and airworthiness. At the time of accident, the registered
owner was African Inland Mission (AIM) International Air Services.
It was classified in the transport (passenger) category and had been
maintained to an approved maintenance schedule.
1.7. METEOROLOGICAL INFORMATION
The meteorological routine report for 1300 hrs at Wilson Airport was:Wind direction and speed
060 at 7 knots
Visibility
more than 10 km
Clouds
Scattered at 10,000 feet
Temperature
24C
QNH
1021 Hpa
1.8. AIDS TO NAVIGATION
At the time of accident the following were the conditions of the aids to
navigation for the non-instrument Runway 07:
 Serviceable Precision Approach Path Indicator (PAPI) on
runway 07.
 Serviceable runway lights.
 Conspicuous and unobstructed runway markings.
 A windsock in good condition.
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1.9. COMMUNICATION
There was normal two-way radio telephony communication between
the aircraft and Wilson Control Tower.
The Air Traffic Controller activated the crash alarm bell immediately
the aircraft was seen sinking into a residential area after reporting an
engine problem. ATC also alerted the Crash Fire Services
immediately the accident occurred. The fire trucks left immediately for
the site at 1045 hrs.
1.10. AERODROME
Wilson Airport has two intersecting runways with the following
parameters:
RUNWAY
14/32
07/25
Length(meters)
1558
1463
Width(meters)
24
24
PAPI
Runway14
Runway 07
Type
bitumen
bitumen
1.11. FLIGHT RECORDERS
No flight recorders were fitted and none were required by regulations
for the type or classification of aircraft.
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1.12. WRECKAGE AND IMPACT INFORMATION
The whole aircraft wreckage remained hanging on the roof except the
right landing gear, which broke off and settled onto the balcony of the
building. The front seats were damaged and detached from the seat
tracks. The co-pilot control yoke was broken, port door detached,
engine mountings broken and the wing leading edges smashed. The
force of impact damaged the avionics with most lying broken. The
aircraft belly pod was smashed and detached from the aircraft.
1.13. MEDICAL AND PATHOLOGICAL INFORMATION
The Chief Government Pathologist performed an autopsy on the
fatally injured passenger under case number 2296/99. He concluded
that cause of death was as a result of chest injuries suffered in the
accident.
1.14. FIRE
There were no signs of in-flight or post crash fire.
1.15. SURVIVAL
The accident was survivable; however, the passenger sitting on copilot’s seat was subjected to massive impact and forward g-forces as
it crashed into the building.
The fact that the accident occurred within sight of the Wilson Airport
ATC Tower, made it possible for rescue personnel to get to the
accident site quickly.
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1.16. TEST AND RESEARCH
The magnetos and fuel system of the aircraft were removed, bench tested
and found to be working within normal parameters.
The engine was also prepared for a bench test without the exhaust and
turbocharger and ran on a McCauley propeller. A rig was set up including a
boost pump, fuel supply, battery and starter. The engine started
immediately on cranking and ran well on different power settings.
Metallurgical examination was carried out on the throttle cable which had
been recovered from aircraft wreckage with a fracture. The examination
revealed the following:
The rod end fitting at the carburetor had separated and was mechanically
damaged. There was a lot of deformation and bending. The fracture
surface texture, cupping of the fracture and the bending of the shank were
typical of a bending overstress separation.
ii)
The outer tube of the assembly had a large indentation on one side
and was flattened on the opposite side as if the tube were trapped and
pinched between two objects.
No indications of pre-existing cracking or corrosion were found on the
throttle cable.
1.17. ADDITIONAL INFORMATION
None.
1.18. NEW INVESTIGATION TECHNIQUES
None.
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2 ANALYSIS
2.1. CIRCUMSTANCES
The aircraft was on a VFR flight from Mwanza Airport to Wilson
Airport. According to the pilot, the aircraft engine experienced a total
power loss between the “Army Camp” and “Monastery” approximately
one and half (1.5) nautical miles from threshold Runway 07.
The pilot reported to have had no engine failure indication or warning
before the total engine power loss.
The aircraft was on a descent profile for a non-instrument approach to
the runway. The runway elevation is 1675 meters (5494 feet) and the
accident site elevation was 1739 meters (5704 feet), a difference of
64 meters (210 feet) above the runway level. With a normal descent
slope of 3, at approximately the 1.5 nautical miles from touchdown,
the aircraft would be flying at a height of about 477 feet above the
runway level. Considering that the elevation of the accident site was
5704 ft, it was 210 ft above Wilson Airport. With a flight altitude of 477
above Wilson, the aircraft would therefore have been flying at an
altitude of 267 ft above the ground level. There were some trees of
about 30 meters (98 feet) in the neighborhood of the point where the
aircraft was reported to have the power loss; hence the aircraft had
about 169 feet above the trees and 1.5 nautical miles to glide to the
runway threshold.
The pilot could not remember the procedure he had followed on
experiencing the engine failure. He had two options available to him
following the engine failure. He could have glided on and attempted to
get to the runway, or make an immediate landing at any suitable
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ground in the vicinity. With the high ground, trees and houses, and
the possibility of failing to glide to the airport, he elected to make an
emergency landing at a school football field adjacent to the runway
extended centerline on the left. Unfortunately, the aircraft flew past
the football field and crashed into a residential house.
2.2. LOADING
The loading of the aircraft was within its maximum permissible weight
and the center of gravity (CG) within the prescribed limits. Hence, the
aircraft certificated weight was in accordance with the approved flight
manual and had not been infringed. Fuel loading was considered to
be adequate for the flight and there was no evidence of a leakage.
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3 CONCLUSION
3.1.
FINDINGS
1.
The pilot was properly licensed.
2.
The aircraft was properly maintained and had a current
certificate of airworthiness.
3.
Aircraft was loaded within C of G limits.
4.
Fuel was sufficient for the flight.
5.
Aircraft could not have glided to Wilson Airport Runway 07.
6.
The aircraft engine and its components test did not reveal any
malfunctions.
3.2. PROBABLE CAUSE
The probable cause of the accident was an engine failure leading to
power loss and subsequent off-field landing due to high ground on the
final approach. The probable cause of the engine failure could not be
determined.
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4 SAFETY RECOMMENDATIONS
1. In order to limit high impact forces to the occupants of the front
seats, both the pilot and passenger of one crew general aviation
aircraft should utilize five-point harness belts.
CIA
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