Conspiracies and FCU Handling
Quote from CONF iture:
And next time you go from flight idle to TOGA tell me if you really have to wait 8 seconds before feeling a kick in your ***
[Unquote]
These insinuations are becoming more and more cryptic; less and less transparent to the normal reader. Can we open up this discussion for normal mortals? In the interests of clarity, and particularly for the benefit of those forumites - unlike ourselves - for whom the events of 1988-90 had little significance, could you please explain precisely your conspiracy theory?
I have no doubt that even half the certificated 8 seconds would have seemed a near-eternity in the situation that M. Asseline and his unfortunate copilot found themselves at Habsheim; one entirely of their own design (not M. Ziegler's). Speaking personally, the video itself told the tale long before the flawed investigation. The fact that the report confirmed what we had already tentatively concluded meant it was of limited interest.
As for the topic this thread is supposed to be addressing − the entirely unrelated accident at Mont St Odile (on a VOR/DME approach to Strasbourg) − the best theory exonerated neither Airbus nor the crew; useful changes were made to the FCU, and significant changes were made to the FPV (flight-path vector) FD presentation and, on the PFD (ADI), the selected values of VS or FPA were added.
The fact is, though, that had the crew been using the FCU-FD interface correctly − that is, by observing the effects of their FCU selections step by step on the PFD, instead of the FCU alone − they could not possibly have failed to notice that they were in VS, not FPA (flight-path angle), mode. [For the uninitiated, they seem to have selected a VS of -3000ft/min (unhelpfully represented on the FCU selection window as –30), in the belief they were selecting a flight-path angle of -3·0°.] Even putting that to one side, the FPA Flight Director command bars on the PFD were and are unmistakeably different from the conventional command bars that would have been presented. Assuming they had rushed the FCU selections in high workload, their apparent failure to notice they had ended up in the wrong flight-director mode cannot simply be attributed to A320 cockpit ergonomics.
Hence, my second question to Monsieur CONF iture: do you have a conspiracy theory on this accident too?
It seems likely that the simple technique I describe was not fully emphasised in their training. We pilots are creatures of habit, and the A320 was the first type to incorporate so much FD information on the PFD. It was only the second civil type to offer the flight-path vector; the first being the A310 of 1983. Other types, including all Boeings and McDonnell Douglases, not to mention BAC 1-11s and Mercures, forced the pilot handling the FCU (whether the PF, or the PNF by command of the PF) to focus attention on the FCU alone while selections were being made.
We all looked at our own habits after Strasbourg; well − the thoughtful among us, anyway. As a specialist line-checker on the A320 for 12 years, the most consistent mishandling I was able to observe (from the relaxed perspective of the jump seat) was the tendency of nearly all ex-B757 and ex-B737 pilots to turn the various FCU knobs and, meanwhile, monitor the changing parameter on the FCU − instead of the PFD. If you think I am exaggerating, let me assure you that it is possible to watch people’s eyeball movements to the point of obsession, but only if you are not personally responsible for the conduct of the flight…
Trust my successors are still taking this matter seriously. It is a practice that MUST be hammered home until it becomes second nature to all pilots of aircraft with sophisticated auto-flight systems and proper PFD displays. Otherwise, Strasbourg may go sadly on to my list of “lessons (not always) handed down”.
Last edited by Chris Scott; 29th Mar 2008 at 09:29.
Reason: Syntax improvements. Spelling changed to disassociate MD from hamburger production...