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Aviation History
2004
2004-09 - 1556.PDF
AIR TRANSPORT INVESTIGATION DAVID LEARMOUNT / LONDON False warning cited in Kenya crash Blank data recorder hampers efforts to determine cause of January 2000 A310 accident, but CVR yields useful clues KENYA AIRWAYS AIRBUS A310 ACCIDENT SEQUENCE 6km A 00.00 Crew sets take-off power F 01.00 B 00.32 PNF: "V, and rotate" G 01.03 C 00.39 PF: "Positive rate of climb, gear up" H 01.05 D 00.41 Start of audible stall warning E 00.50 Radio altimeter: "300" I 01.06 PF: "Silence the horn" Radio altimeter: "50" Start of continuous repetitive chime (PNF: "Go up") First sound of impact Note: PF (pilot flying) PNF (pilot not flying) Time is elapsed since take-off power application 1min S) cation \J FLIGHT 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 air port's runway 21 see diagram). After a normal take-off roll with the flap lever set to 15°, 8s after rotation the audible stall warning and stick- shaker activated as the co-pilot - the pilot flying (PF) - called "posi tive rate of climb, gear up". Although the captain acknowl edged 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% N, (fan RPM). The aircraft gradually descended until impact with the sea, killing all 10 Teams led by BAE Systems, Nor throp Grumman and United Air lines will learn within weeks which of the three is to receive US govern ment contracts to begin flight test ing systems developed to protect air liners from missile attacks. The US Department of Homeland Security (DHS) was scheduled to announce the second phase in its Counter Manpads (man-portable air defence systems) programme by 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 gener ated by the radio altimeter was audi ble 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 spec trum analysis, and aircraft accelera tion 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 mid-August, with two teams likely to receive contracts to flight-test their systems. The DHS says the selection will be made before the end of this month, but says it does not have an exact date. Earlier this year, the DHS allotted each team $2 million to develop a plan to adapt military missile detection and countermea- sures technology for commercial aircraft under phase one of 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 Counter Manpads programme. Phase two, an 18-month pro gramme, requires the chosen team or teams to finalise designs, flight- test the systems, acquire US Federal Aviation Administration certifica tion, analyse costs and provide training requirements. The DHS is targeting a maximum per-flight cost of $500 for airlines to use the Counter Manpads device. The BAE-led team, comprising their failure to apply take-off/go around thrust (117% Nj) at the warning onset, and the lack of any recorded action from the captain, who was the pilot not flying (PNF), until Is before impact when he said "go up". Airbus says it modified the stall warning guidance in its flight- crew operations and training manu als by January 2002 in the light of report recommendations. Delta Air Lines and Honeywell, and the Northrop Grumman-led team, including FedEx Express and Northwest Airlines, are both offer ing laser-based directional infrared countermeasures systems derived from equipment already in produc tion for the US military. United leads a consortium that proposes using a decoy-based sys tem, whereby flares would be used to decoy infrared-guided missiles. COUNTERMEASURES MARY KIRBY / WASHINGTON DC US contracts for anti-Manpads to be decided More crew training urged The report recommends that all crews of transport aircraft should be exposed, during type conversion and recurrent training, to false stall warnings to "sensitise [them] to the possibility of false warnings", to train them to manage all stall warnings, and recog nise and manage false ones, especially in the case of warnings close to the ground. The investigators asked Air France for a record of false stall warnings to judge their frequency, and the air line provided details of one on an A310, five on Boeing 737s, and one on a 747, although it did not say over what period. None led to an accident or incident. Airbus says there have been "no false stall warnings of this kind" before. www.fliqhtinternational.com FLIGHT INTERNATIONAL 24-30 AUGUST 2004 13
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