Saturday, August 04, 2007

Update on TAM crash in Sao Paulo

TAM Airlines tailOver the past few days, there has been a lot of speculation in the press that pilot error was to blame for the crash of TAM Airlines Flight 3054 at São Paulo's Congonhas airport last month. The speculation began after it was revealed that the crew retarded the thrust lever for the number one engine during touchdown, but left the throttle for the number two engine in its forward position.

Some news media not specialized in aviation matters seem to have concluded that this was an illustration of pilot error. Aviation industry insiders are not so quick to assume that pilot error was the reason that a throttle was in the wrong position, noting that it was possible the pilots had shifted the throttle lever correctly but that the plane's computer had failed to respond due to a mechanical failure.

According to a report on Flight that quotes industry sources:
For reasons yet to be explained, the pilot, in the final moments before touchdown, retarded only the thrust lever for the left-hand engine – first into the ‘idle’ position, then into ‘reverse’. This action disconnected the auto-thrust, as per its design. The failure to move the right-hand engine’s thrust lever to the reverse position runs contrary to the standard operating procedure which calls for both levers to be set to ‘idle’ and then 'reverse' – even with a thruster reverser inoperative.

It is unclear why the right-hand engine thrust lever was left in position. Newly-released cockpit-voice transcripts have notably highlighted the crew’s awareness that only the left-hand engine had an operable thrust-reverser; the right-hand reverser had been deactivated. This, however, should not have made a difference to the thrust retardation procedure.

As the aircraft began to slow after touchdown the thrust being produced by the right-hand engine remained at the level it was at when the auto-thrust had disconnected. With the thrust lever forward the spoilers would not have deployed, and the auto-brake would have similarly been inhibited.

In the cockpit transcript the co-pilot appears to state that the A320’s spoilers did not activate on touchdown and, as the situation develops, the pilots are heard to say that they cannot slow the aircraft. Flight-data recorder information indicates that the pilots repeatedly pressed on the brakes in a bid to stop the jet but did not retard the right-hand thrust lever.
Officials at Brazil's aviation accident investigation agency, CENIPA, have pledged to keep an open mind about the cause of the accident, saying that the investigation will cover mechanical or system failures and pilot error as well as airport infrastructure.

An English translation of the TAM Flight 3054 CVR transcript has been posted on the website, along with an interpretation of the clues to possible causes of the crash that the transcript provides.

Related: Click here to view all posts on this blog about the TAM Flt 3054 accident.