David Learmount/LONDON
Any remaining doubt about whether the crew of the stricken Swissair Boeing MD-11 was attempting a ditching has now been eliminated by examination of wreckage on the seabed. Investigators have found that the aircraft, when it hit the water at night off Nova Scotia, Canada, on 2 September, was definitely in a nose-down attitude, but the angle of impact has not yet been determined and no estimate of the speed has yet been offered.
The Canadian Transportation Safety Board (CASB) says the cockpit voice recorder (CVR) did not reveal any fire alert despite the crew distress call reporting smoke in the cockpit, and that the pilots' conversation has not revealed any significant clues. The CVR is now being studied in detail, however, for background noises to determine what was occurring.
The investigators have also suggested a possible cause for the CVR and flight data recorder (FDR) turning off simultaneously about 6min before impact. This could have happened, they say, at about the stage when the crew, going through the checklist for fire, reached the card on "smoke/fumes of unknown origin". The checklist actions include switching off power to the busbars which supply the CVR/FDR.
The CASB, meanwhile, has issued a strong denial of press reports implying evidence that the pilots may have been driven from the flightdeck by heat before the impact, insisting that there is no such evidence. Hope is emerging, however, that although the investigation will be "painstaking", the wreckage and data will yield the essential information to pinpoint the cause of the accident.
The wreckage on the seabed is confined to a small area measuring about 70 x 30m (230 x 100ft), the CASB says, with more extensive fragmentation at the front than at the rear of the fuselage. The full authority digital engine control (FADEC) for the starboard engine has been recovered and is known to hold some data. The FADEC is being examined by manufacturers Pratt & Whitney and Hamilton Standard, and the data will be correlated with air traffic control tapes, radar records, and the information from the CVR and FDR.
Source: Flight International
