A340 AIRPROX - pitch-up
Quote from me, commenting on A340 AIRPROX of 2001:
"... although the overspeed was also a factor in the pitch-up."
Reply from HN39:
"Was it ? ...."
I'm rather hoping you can answer that, HN39. After the overspeed of Mach triggered the disengagement of the AP, was the peak Mach of M0.882 corrected by EFCS overspeed protection, involving a pitch-up with neutral sidesticks?
There are obstacles facing many of us when reading the AAIB Bulletin.
(1) After AP disengagement, the precise timings of the increase in speed from M0.855 to M0.882, and the rate of speed decay thereafter, are not included in the narrative.
(2) The absence of a trace of the Mach parameter in their DFDR presentation. Many of us are unable to apply the necessary parameters of SAT and FL to calculate Mach from the CAS trace. So we cannot observe the changes of Pitch alongside Mach. An associated, perhaps minor, difficulty is the unclear annotations on their time scale.
(3) We do not have the overspeed-protection criteria pertaining to the a/c at that time. Was an overspeed of about M0.02 sufficient to trigger it?
On the other hand, did the rise of CAS in itself cause or contribute aerodynamically to the pitch-up? And what effect would such a rise of pitch have on the AoA, and its rate-of-change?
Last edited by Chris Scott; 10th Nov 2013 at 14:48.
Reason: Last paragraph added.