Originally Posted by
CONF iture
MFS,
My position is that everybody has to learn something from an accident, and the Manufacturer is not to be excluded.
It takes absolutely nothing to trigger an AOA DISCREPANCY ECAM MSG meaning :
"Eh guys, our AoA probes disagree, the probabilities are on our side, we believe the faulty probe has been identified and you can resume normal operation. In the meantime, as we have been proved wrong a few times already ... if your intention was to test the system today, don’t do it, and if by adventure you was unlucky to need maximum performance of the system, don’t rely too much on our protections today, but simply use your own abilities a bit like if you were flying a 737"
Don’t you agree such message could positively influence a crew and therefore improve the level of awareness and safety ?
In circumstances where a single discrepant probe has been discarded and the system now relies on two, I doubt such a message helps. The aircraft I am most familiar with only has two AOA probes to start with, and we need those at least as much as airbus does theirs. And except in this very odd case where the functional probe has been dropped, if the message has no crew action required, why post it? It certainly shouldn't be an amber Caution, as you colouring would suggest. At most it'd be a white/blue advisory, and I really wonder why we post those, since we are allowed no credit for them in considering crew response.
I agree 100% that the manufacturer needs to learn from every action; none of us take accidents or incidents to our products lightly. In this case, though, and as I alluded earlier, its unfortunate that Ab don't appear to have a scheme to determine that a probe value is valid - in the sense that there is no known fault with that sensor - but still likely erroneous. In this case, anyone looking at the DFDR trace sees those completely static AOA values with changes in speed and configuration and a big red light goes off in your mind. The system monitoring the AOA data could have done the same thing. "Before I vote out bad data, let's see if any of the data hasn't moved in, say, the last minute. hmm. zero change, at the hundredths of a degree level, in a minute. AOAs don't do that. Lets discard those ones instead ..."
With the amount of redundancy in modern systems, posting a message every time you lose redundancy would overwhelm the crew. Its only merited, in my opinion, if it brings you to a point where you are a single failure away from trouble. In this case, they were not supposed to be that close to trouble.
To address the issue of a message stopping a test - that's why some aircraft have test-specific configurations and strappings, to ensure that stuff you need for test is available, but does not clutter up the normal displays.