Blank data recorder hampers efforts to determine cause of January 2000 A310 accident, but CVR yields useful clues
The crew's inappropriate reaction to a false stall warning was the probable cause of the 30 January 2000 Kenya Airways Airbus A310 crash off the coast of Abidjan in January 2000, says the Ivory Coast ministry of transport investigation team's report.
The probe was hampered by the fact that the virtually undamaged flight data recorder (FDR) failed to record any useful information, though the cockpit voice recorder (CVR) yielded strong clues.
The outcome of the investigation was predicted in transport ministry statements as early as August 2000, but the report itself, approved by the Ivory Coast investigation team in January 2002, has only just been made public by French accident investigation agency BEA, one of the parties to the inquiry.
The accident happened during a late night take-off from Abidjan airport's runway 21. After a normal take-off roll with the flap lever set to 15°, 8s after rotation the audible stall warning and stickshaker activated as the co-pilot - the pilot flying (PF) - called "positive rate of climb, gear up". Although the captain acknowledged the co-pilot's instruction, the gear was not retracted.
The aircraft had not yet reached 400ft (120m), but the PF's reaction was to lower the nose leaving the power at 97% N1 (fan RPM). The aircraft gradually descended until impact with the sea, killing all 10 crew and 159 of the 169 passengers.
The audible stall warning alert, which the investigators say was false because they estimated the aircraft was flying at a safe speed, continued until 5.5s before impact, when the PF ordered it cancelled. Meanwhile, the voice height countdown generated by the radio altimeter was audible from the 300ft call-out down to the 10ft call, just after which the flap overspeed alert sounded because the high power setting and descent had increased speed.
In the absence of any useful data on the undamaged FDR tape - read by the Transportation Safety Board of Canada (TSBC) - the investigators used wreckage study, sound spectrum analysis, and aircraft acceleration rates as calculated against crew speed call-outs to deduce that the aircraft did not approach the stall. They also calculated that the A310 was properly loaded and that the assumed weights and take-off speeds were correct. Apart from the false stall warning, for which no specific cause could be deduced, there appears to have been no fault with the aircraft or avionics, and the aircraft was correctly configured for take-off, says the report.
FDR manufacturer Honeywell and the TSBC say the recorder was probably working, but was blank because the data feed was faulty.
Criticisms of the crew included their failure to apply take-off/go around thrust (117% N1) at the warning onset, and the lack of any recorded action from the captain, who was the pilot not flying (PNF), until 1s before impact when he said "go up". Airbus says it modified the stall warning guidance in its flightcrew operations and training manuals by January 2002 in the light of report recommendations.
DAVID LEARMOUNT / LONDON
Source: Flight International
