David Learmount/LONDON
Initial evaluation of the crashed EgyptAir Boeing 767-300ER cockpit voice recorder (CVR) and flight data recorder (FDR) has failed to confirm the causes of the dive which began the fatal manoeuvre sequence, says US National Transportation Safety Board chairman Jim Hall.
On 17 November, Hall released a statement headed Factual update on EgyptAir investigation, which gave the following sequence of events on the flight:
• In the cruise at 33,000ft (10,000m), the autopilot cut off. Eight seconds later, the elevator moved into the nose-down position and the throttle was pulled back;
• 14s after the nose-down, the aircraft reached Mach 0.86 and the master warning sounded;
• 13s later, the engine start lever went to the off position;
• 14s after that, the FDR, CVR and transponder shut off. From autopilot cut off to the end of data was about 50s;
• the last registered altitude was 16,400ft, at which time the aircraft was flying at 574kt (1,062km/h) true air speed.
In the last few seconds of FDR recording, pitch attitude moved from 40° nose down to 10° nose down and the speed brake handle moved from stowed to deployed. Radar data show that the aircraft pulled up from 16,700ft to about 24,000ft before descending into the sea, with primary radar returns indicating aircraft break-up.
About 15s before FDR cutout, at the pull-up after the initial descent, the FDR indicates a 2.5g pull up and a 7° split in pitch angle between the left and right elevator. The left (captain's) elevator was selected nose-up, the other nose-down.
There is design provision for elevator split only if one elevator control system has jammed, when a 22kg (50lb) pitch force applied on the other control column will cause independent operation of its corresponding elevator.
The CVR reveals that the standby co-pilot, who took control shortly before the autopilot disconnected, had muttered a short Islamic prayer. It has not been determined whether this was a personal custom, a reaction to something which went wrong or, as an unofficial Federal Bureau of Investigation leak has implied, presaged a pilot suicide attempt. The recording has not indicated a problem before the descent or conflict between the pilots.
One pilot enters the cockpit shortly after the descent began, however, and says: "What's going on?", adding: "Pull up, pull up!" Hall says that a CVR transcript is expected to be ready this week.
Source: Flight International
