CONF iture;
That's the main purpose of the forum; glad it was of help.
Re "experimenting", in Line Indoc instructing, under appropriate circumstances I would encourage moving between fully automatic flight into fully manual flight and back again. That means disconnecting the a/p, then the autothrust, then the f/d's and then reconnecting them again.
Disconnecting the a/t's especially; I noticed that when it was the F/O's leg and I indicated that they were free to hand-fly the airplane to from takeoff to cruise and from top of descent to touchdown, most refused because I think they were uncomfortable. Good reaction in the immediate sense but I didn't think much of the lack of willingness to learn. There are a few circumstances where hand flying and manual thrust are required by the MEL and one had better know the numbers.
The other 'gotcha' which I used to emphasize and when appropriate, demonstrate so that the candidate knew what it looked like and knew what to do, is the THRUST IDLE/OPEN DESCENT mode when hand-flying and for whatever reason, not following the flight directors. Leveling off before ALT* will leave the F/Ds (and the engines) in the Open Descent mode. Since there is no capture, the power does not increase and the speed begins to bleed back for no apparent reason, (no warnings, nothing apparently wrong) and the engines remain at IDLE thrust.
This is what occurred in the accident at Madras. Airbus has since addressed this by causing the Thrust mode to revert to SPEED from THRUST IDLE at Vls + 4kts (if I recall). The sudden increase in thrust to re-capture the managed speed is very surprising, and tells the passengers that something happened up front. Deadheading Airbus guys will know. The key is to either turn off BOTH Flight Directors which causes the THRUST mode to revert to SPEED, or to disconnect the autothrust and increase the power manually.
The opposite problem occurs if one tries to control a speed problem by "disconnecting" the autothrust while leaving the thrust levers in the CLB detent. Can you imagine what would happen?!
Not activating the approach would be one more item of interest. Since this must be done manually on the FMGC, forgetting to do it means that a rapid thrust increase will occur when landing flap (Conf 3 or Conf FULL) is selected because the FMGC no longer has a speed reference for the approach, (it is still in the DESCENT mode) and so will go for the last speed it "knows"....250kts! I'm sure this was demonstrated in the sim, but if not, a swift retarding of the thrust levers to prevent an overspeed of the flaps and destabilization of the approach may rescue the situation and you can re-engage once things settle down and the approach is activated. Likely the best response is to go around but on the Quiet Bridge at SFO or the Visual onto 31 at LGA and other places, it may be a long time before you get on the ground. A go-around and a normal circuit and approach usually cost 400kg. At these places and others, it can cost more.
Sorry to drone on...this probably belongs on Tech Log forum, CONF iture.
Re recommendations to Airbus...I can say that FOQA information is invaluable in determining if there were any cases where A320 thrust levers were "split" at touchdown and if so, by how much and for how long. I would think that most airlines modified their SOPs to ensure that BOTH thrust levers were closed by touchdown and that no RETARD calls should be heard by the crew. There may even be a "SPOILERS UP" call now required, (was never called before).
As to why to high-time professionals left one thrust lever in the CLB position, that is a disturbing mystery - disturbing because by all accounts these guys were highly experienced, competent pilots with loads of time on the Airbus. In the time they had to analyze what was wrong, I'm not sure any warning would have been able to help.
Last edited by PJ2; 2nd Nov 2009 at 01:00.
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