BA038 (B777) Thread

[PETTIFOGGER]

SFLY

The report says that:

• The PF intended to disconnect the AP at 600 ft.
• He was distracted and omitted to do so (AP remained non-intentionally connected)
• He believed it was disconnected (not aware that it was until stick shaker)

I do not speak for the crew but ~
What you have written above is an interpretation of the AAIB report which is almost accurate, but not quite. I prefer to keep to the exact text of the report and its conclusions, neither adding to nor subtracting from it. For ease of reference, I should like to quote 6 of the conclusions from the AAIB report which seem to be the most relevant to your concerns.

Conclusion 15. “The co-pilot intended to disconnect the auto pilot at 600 ft but became distracted by the engine rollback, so the autopilot remained engaged.

16.The loss of engine power led to a reduction in airspeed as the autopilot attempted to follow the ILS glideslope, leading to a nose-high pitch attitude.

17. Thirty-four seconds before touchdown the flight crew became concerned about the reduction in airspeed below the target approach speed and attempted manually to increase engine thrust to compensate; there was no response from the engines.

18. At 240 ft agl the commander retracted the flap from FLAP 30 to FLAP 25 which increased the distance to touchdown by about 50 metres; if left at FLAP 30 the touchdown would have still been within the airfield boundary.

19. At 200 ft agl the stick shaker activated and as a touchdown short of the runway was inevitable the commander transmitted a ‘MAYDAY’ call three seconds before touchdown.

20. At the operation of the stick shaker, the co-pilot pushed forward on the control column and the autopilot disconnected."

There is a subtle but important difference between these 6 AAIB conclusions and your three. In my opinion, they allow more insight of the causal processes of this accident as it developed than do yours. One could argue that the delay in disconnecting the autopilot was a consequence of the engine rollback, which began at 720 ft agl but only became known to the crew at 430 agl. Even then, they cannot have been sure that they would not get the power back. There is no big red flag that pops out and says ‘sorry chaps, that’s it for today.’ So it was entirely reasonable to continue to follow the ILS glidescope, whether assisted by the autopilot or not. There is no suggestion in the report that the PF was not monitoring the approach with hands on the yoke.

SFLY My understanding is that:

• Keeping the AP was not intentional
• The PF wasn't aware that he wasn't actually controlling the aircraft between 600 and 175 ft (what about the PNF?)

Wasn't there a crew awareness problem between 600 and 175 ft with nobody knowing who/what was actually controlling the aircraft for almost one minute?

Your first point above is answered by Conclusion 15.
Concerning your second point, I choose to believe that he was aware that he was in control because he would have had his hands on the yoke if he thought he had disconnected the AP. The fact that he had not disconnected it is irrelevant because any firm input leads to immediate disconnection, as happened at 200 ft agl. This answer also covers your third question.