The Singapore Airlines jumbo jet which crashed in Taiwan on Tuesday tried to take off from a runway closed for maintenance and ran straight into two excavators, according to a prosecutor investigating the accident.
"We can be sure that the plane took off from the wrong runway. It hit the construction equipment while taking off. It had not left the ground," said a senior Taoyuan county prosecutor, Mr Song Kuo-yeh.
The finding is a setback for Singapore Airlines, which had hoped that the inquiry would exonerate the pilot and show that the crash occurred because of outside events over which it had no control.
The Boeing 747-400 with 179 people aboard crashed in flames while taking off for Los Angeles in a typhoon, killing 81 people and injuring 82. There had been speculation that the aircraft was forced to ditch by a severe gust of wind, or had collided with an object blown into its path by the storm.
While the driving rain would have made vision difficult, the key question now is whether the runway lights were on, and if not why the captain used an unlit runway. Some of the surviving passengers, including an Irishwoman, Dr Deborah Brosnan, do not recall seeing runway lights as the aircraft gathered speed for take-off.
A Singapore Airlines spokesman, Mr Rick Clements, said yesterday: "When the possibility of a runway mix-up was suggested two days ago, we said at that time that it was unlikely an experienced captain could have taxied his aircraft on to a darkened runway that was out of use. But the aircraft was on the wrong runway, and we want to understand now how could this have happened."
Both taxi lights and centre lights, running the length of the two runways, were on, said Mr Yong Kay, managing director of the Aviation Safety Council conducting the investigation.
But it was not clear if the takeoff lights, running along the sides of the closed runway, were on, he said. The take-off lights are spaced at different intervals so the runways can be distinguished more easily.
Mr Song said the aircraft took off on runway 5R (right), which was closed for repairs, and struck two excavators. The control tower had given clearance to the pilot to take off on runway 5L (left) which was operating normally.
The pilot had acknowledged the clearance, saying: "Confirm runway five left," Mr Song said, "but that may or may not necessarily mean that he was on which runway. He is merely repeating that he heard the clearance from the tower and repeating that back."
The recording of the conversation with the control tower has been downloaded from the black box, officials said. Most of the wreckage was on the closed runway, and the flight data recorder indicated flight SQ006 had maintained the same direction during the attempted take-off.
Dr Brosnan, originally from Limerick, and her British husband, Mr Steven Courtney, are expected to leave Taiwan today or tomorrow for the United States. Mr Courtney received burns over 20 per cent of his body and will require specialised treatment in a US hospital.
The aircraft's captain, Mr C.K. Foong of Malaysia, was also unhurt.