Originally Posted by
takata
Hi sensor_validation, bekolblockage, everybody,
A340 AIRPROX;
Full thrust was not from protection. The report messed up stuff.
Alpha_floor (as quoted in report) is inhibited above Mach 0.53 if I remember correctly.
Autothrust was disconnected by the crew: they should have received a THRUST LOCK signal (no ALPHA LOCK as reported).
Thrust increased from under 70% N1 (where the autothrust settled it because of the overspeed event before manual disconnection: overspeed protection is first managed by the autothrust) to 100% N1 in a short while. It is unclear if it was due to manual action (I guess it was because N1 was previously stable around 90% before turbulence encounter).
In this case, the climb (and pitch increase) is related to this sharp thrust increase (4 engines at 100% N1), being not countered by nose down imput from the PF.
Autopilot was first disconnected due to overspeed (it was not due to Alpha prot).
This TCAS event just added to the confusion.
Stick pitch axis data on the graph seems also inverted (or alpha_prot kicked at the top of the climb, but it is hard to see it without any AoA data track pictured on the graph - quite disturbing as to suport the AAIB comments).
Hi takata,
As discussed earlier, there was no fault found with the controls at the time, the issue investigated was the near-miss. What is clear is that the pitch up in the A340 was after A/P and A/T disconnect, and before any sidestick input, but curiously I now see the stab was moving. The pilot inputs to Mach Speed setpoint before A/T disconnect or manual throttle after are not shown. If the pitch up caused by manual throttle change (CAS had fallen significantly) - is it not true a twin engine A330 has more excess thrust than a four engine A340 (both are certified to take-off with loss of one engine)?