But he advanced no new theory about what had caused the crash. Jim Hall was releasing preliminary information from the flight data recorder, recovered from the ocean bed 36 hours before.
He said data from this first "black box" showed the flight proceeding normally, with the plane at an altitude of 33,000 ft, when the autopilot was disconnected. Eight seconds later the plane began what appeared to be a controlled descent.
It was tracked as far down as 19,000 ft, which was consistent with available radar data. Mr Hall said that, contrary to some reports, it did not appear to have reached supersonic speed.
Mr Hall said there remained another 5-10 seconds on the tape still to be analysed. But he went a long way towards ruling out a faulty thrust reverser as the cause of the crash, saying: "There is no evidence of thrust- reverser deployment in the data we have." Faulty deployment of the mechanism was blamed for the crash of an Air Lauda Boeing 767 over Thailand in 1991 and was an early theory in the EgyptAir crash. Mr Hall declined to draw any conclusions, but expressed confidence that the second black box, the cockpit voice recorder, would be found.
t A DC-9 jet crashed in central Mexico on Tuesday, killing all 18 people on board.