Originally Posted by
bsieker
I think that point of view is exactly right. More importantly even than to know
what those flight crews were doing is to make a useful theory of
why they did what they did. After we figured out what they did, which should be relatively straightforward from the recordings.
The very few cases of suicide notwithstanding, it is practically always the case that to professional operators suffering an accident (pilots, ship captains, train drivers, excavator operators, chemical plant engineers, ...) what they were doing made sense at the time. Only with hindsight does it seem obvious that it was wrong, and once we know the "correct" solution it seems impossible to miss. But we cannot really evaluate the situation they were in at the time.
I hope Professor Dekker won't mind if I use a small picture from his highly recommended book
The Field Guide to Understanding "Human Error" (quotes original) to illustrate:
(2009 Sidney Dekker)
Bernd
Hi Bernd;
I'm sure Professor Dekker won't mind a bit!
As you'd know, he also states, "
What (you think) should've happened cannot explain people's behaviour", (
The Field Guide to Understanding "Human Error" - Dekker, Ashgate, 2006). In fact, rather than possessing pilot licences, this specific book among all of Dekker's excellent works should be required reading as a condition of PPRuNe participation! ;-)
BTW, I fully agree with you regarding your views on AoA. AoA is for downstream equipment to use. Even though it appears to be obvious, I don't think AoA is the magic bullet some make it out to be and I don't think the case has been demonstrated for it's inclusion in an already-crowded PFD. In fact, there are
no saves on record that occurred as a result of pilots knowing their AoA.
The question is, why did two AoA sensors, the one from the flight previous to the accident flight, and, (after having been changed), the accident flight AoA sensor have the same, identical incorrect AoA value? I've looked in the AMM - the installation is "keyed" so an incorrect install is unlikely, and the test procedures are thorough. Even if, hypothetically, not done, I am informed that these sensors are rarely wrong. Also, while poor operation of the loading bridge can possibly damage the left AoA, all such instances have been caught on the walkaround. (For those who don't know the aircraft, the AoA sensor is
well forward of the L1 door).
PJ2