Originally Posted by CONF iture @ Post #357
I would not disagree as the altitude margin was confortable this time, but nevertheless, I see AF447 as a compulsory trigger to modify the UAS procedure to something that makes sense in any circumstances.
One way of perhaps making a change which retains the essential and necessary actions in the original drill is to modify the qualifying condition at the start of the memorized drill, which is, "
If the safe conduct of the flight impacted". There is little guidance on how to make this decision in a hurry. In some explanations, the "safety of the flight is impacted" if all three airspeed indications fail". While such an assessment is probably a wise and accurate one, I disagree that the automatic response to this qualifier in the drill should be a pitch-up to 5deg.
The drill was originally conceived to deal with pitot or static system failures close to the ground, the takeoff phase being the obvious and most critical phase. The memorized items, as I have argued, cater to the takeoff phase, and, I have argued, the "Above FL100" caters to the climb, perhaps even out of high altitude airports, but
not to cruise levels where the aircraft is already in stable, level flight. I submit that it is a mistake of interpretation and lack of clarity in the drill, to execute the 5deg pitch-up using this qualifier. This qualifier is followed by three items and the statement, "
When at, or above MSA or circuit altitude, level off for troubleshooting". Well, one is already well above MSA and is already levelled off. Why divert from that qualifying condition, only to return to it "quickly", as the "How to do this drill" notes require?
If the memorized items are to be correctly placed and the subjective, very individual assessment as to whether the "safety of the flight is impacted" avoided if the memory actions are qualified not by "the safety of the flight" but by flight phase and by altitude. Then the drill is much more clear as to what actions to take. Qualifying by flight phase and altitude are the first memory items after the "safety of flight" qualifier anyway.
So it might look like this:
DRAFT - DO NOT USE - FOR DISCUSSION ONLY:
As Clandestino has pointed out, these drills and checklists have been created carefully by test pilots and others who know this work thoroughly. The suggestion for change will have implications not imagined or considered and clearly needs examination by many others. But the basic notion is removing the initial qualifier to define more precisely, where different behaviours, (crew responses) will occur. I think that confusion and the training resulting from this confusion is at the heart of the initial pitch-up - what cannot be explained in this view is the immediacy of the response and the absence of SOPs and CRM.
Changing drills and checklists occurs all the time as new knowledge and experience emerge. This is normally done through meetings between checkpilots, standards pilots, flight safety/flight data people and so on and is otherwise a process with heavy vetting of such changes.
In fact, the UAS memory items and ADR Checklist have perhaps half a dozen iterations from around 2001 on - the first drill did not mention "levelling off" at all and was a straight response to the Birgenair and Aeroperu accidents. However, the B727 pitot-icing event pointed out by a poster recently, was not considered, nor, I believe, were pitot failures at cruise altitude until after 2002 or so even though such failures had been occurring since 1996.
There are other serious matters at hand which this accident has made clear. But the accident sequence began with the instant pitch-up, with no SOPs followed, and it is important to establish why this occurred and to take measures to examine and change those reasons.