Chris &Dozy
Some more thoughts on the A340 incident:
The report states “ The over speed warning(“OVERSPEED”) was triggered(3) andthe “Master Warning” warning light came on. The crew stated that they were very surprised by this warning. Mach reached 0.87.” The warning is set to trigger at MMO+.006 i.e.M.866 and it triggered correctly why was the crew surprised? The report says “during the event the high speed protection was not activated”. This is surprising as it should have activated and according to A340 FCOM “The autopilot disconnects when high speed protection goes active”.
The report says” F-GLZU recorded data showed that the AP would have remained connected if it had not been manually disengaged”.I don’t see any guarantee of this as high speed protection should have activated or was about to activate and that would have disconnected the AP.
Then the PF disconnected the AP and applied ¾ back stick which put the aircraft in high AOA protection.
“From the start of thepitch-up input until point n°9, the high angle of attack protection was activated several times”. This statement has been misunderstood by some bloggers as automation causing unnecessary pitch up to Valpha MAX. This is not what happens in AOA protection rather it only can cause pitch down to Valpha prot with stick neutral. However if AOA is left at Valpha prot then the mode of pitch control may keep changing from load factor to AOA mode as the AOA changes due to disturbances. That is not same as pitching up and down. The only thing is if left alone, in AOA mode it will stabilize at alpha prot speed. In any case Pilot’s action should have been to push the nose down and recover the speed. So automation has not played any adverse role in this.
Last edited by vilas; 9th Nov 2013 at 09:21.