Originally Posted by
Welsh Wingman
(1) To be fair, I have added "inadvertently" to point the "blame" in the sales direction.
I know, just thought I'd reinforce it for the benefit of non-native English speakers who may not pick up the inference as easily as I did.
(2)...Would the PNF have been more assertive if he could have seen what the PF was specifically doing through a clearly visible RHS control column (or at least if the LHS SS was moving in tandem with the RHS SS movements commanded by the PF?)? The throttle moving also? Would the PNF at least have been better placed to properly brief the returning CDB? Might this have overcome CRM shortcomings and saved the day?
Well, that's a difficult question - and as I said, one that the human factors bods will be debating back-and-forth till kingdom come. Common sense suggests that it might have made a difference, but on the other hand there's the CVR that suggests that the PNF might have been aware that his colleague was overcontrolling even without feedback, as well as the historical cases (Birgenair, NWA) where the PNF in both cases had the yoke in front of them reflecting the PF's inputs, and still failed to put two and two together.
(3) "Design assumptions" are always dangerous. The Titanic was "unsinkable" because how could White Star possibly flood the first five watertight compartments.....? What floats, can sink. What flies, can stall. A stall warning really should stay on until an aircraft is no longer stalled. The stall warning ceasing just after the CDB returned to the cockpit was, at best, "particularly unhelpful".
Of course they are, but as I'm sure you're aware, design and engineering are and have always been underpinned by the art of compromise. In this case (as I said above) there was a history of incidents where the number of false stick-shaker events led to an assumption on the pilots' grapevine that most stick-shaker events were false, with fatal consequences when a real stick-shaker event happened. Manufacturers were then faced with the task of weeding out the circumstances in which the stick-shaker was a false alarm, and Airbus's logic was based on a set of parameters that were so outside the flight envelope that they couldn't see it happening with the aircraft aloft - it's possible other manufacturers have done the same and at the risk of repeating myself I hope they all band together to find out.
The Titanic (another minor obsession of mine as it happens) and the Comet 1 were both examples of designers working at the limits of contemporary knowledge (regarding worst-case maritime collision scenarios in the former and metal fatigue in the latter). Now we know that it is possible to stall a modern airliner to such a degree that it intersects the stall inhibition parameters, it's likely that designs are going to have to change.
(4) We Brits naturally prefer "evolutionary", which is why I value PJ2's viewpoints on the more "revolutionary" aspects of the AB design philosophy.
Now my old Prof considered the A320 more "evolutionary" than "revolutionary" once he got to poke around inside, the only difference being that the aircraft it evolved from (the A300/A310) was already probably the most technologically advanced airliner flying up until that point (though again, as I said before, the L-1011 came close). It depends on how you look at it - most of the circumstances that made two large, connected central control columns necessary in the first place (largely to do with leverage when the flight surfaces were directly connected by cable) were no longer applicable by 1972, let alone 1982 when the A320 was being specified.
From Stony Point through Aeroperu and Birgenair to Colganair, there are stall warning issues and pilots forgetting their training and grimly pulling back on their control columns.
Aeroperu was slightly different - loss of pitot data affects airspeed indications, and as long as you click the A/P off, it's relatively straightforward to manage. Aeroperu had the static ports taped over, which was a whole other ballgame in terms of what it did to the instruments.
Hopefully, with control column pilots now acutely aware of the "stick shaker" issues after numerous hull losses, there won't be a SS repetition.
Fingers crossed!
This is an across the board training issue. The less routine manual flying that pilots do on any aircraft (within the flight envelope), the harder it is for them to suddenly "ride to the rescue" in a degraded flight envelope emergency. That must be self-evident........
Absolutely - but the pressure must be brought to bear on the airlines, specifically management, that the status quo is not on, and again - as I've said before - who will be the first to stick their head above the parapet?