Hi 3holelover:
Originally Posted by
3holelover
I don't believe that to be the case. The stick's neutral position, in both axes, is fairly certain... it's rather easily maintained in that 'detent' - if you will - of one axis while being moved within the other.
Thank you for that, and I'm happy to be corrected. I can only speak from my GA (control column) piloting experience, where no such neutral "detent" or bias exists. Now you mention it, the SS "detent" you mention, sounds rather like some PC joysticks
Having said that, I still believe that even with such a "detent", in a high-stress situation, the effects of adrenaline could easily overpower the PF's fine muscle control which is needed to "respect" such a bias toards neutral pitch. Therefore the only way to
ensure that such a neutral bias is respected by a pilot who is "high" on adrenaline, may be to
enforce it with some kind of lock. I'm sure that would bring its own set of challenges, however...
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Hi Machinbird, Thanks for your thoughts.
Originally Posted by
Machinbird
A key element of manual instrument flying is building a mental picture of what the instruments are telling you and then controlling the aircraft with that information. With a PFD, it is much easier than with steam gauges since the majority of data is in a narrow visual span.
My present conclusion regarding the PF's control problems is that his scan was broken and disfunctional. His problems were very likely compounded by an inappropriate grip of the stick from the start, i.e. palm instead of finger tips.
I've done limited IFR training, but your comments certainly make sense to me.
The core of a manual instrument scan is control of the nose attitude and roll attitude-just put the pipper above the horizon line by the appropriate amount (~3 degrees in this case) and level the wings. Then drag in peripheral data from the sides, altitude, heading, and airspeed. Make small corrections as necessary.
Perhaps, in the heat of the situation, with immediate roll inputs being required, this seems to bring us back to the PF being "behind" the aircraft and its initial state (inc. attitude), so that his NU inputs changed that state before he could get a good scan going (if that ever happened).
I also think the subsequent changing of what instrument data was available and
valid (especially airspeed and v/s) could easily have led to confusion over which data to trust & which to ignore. Of course with hindsight, we can see there was "only" incorrect airspeed & intermittent loss of v/s indication - but he didn't know that
I can see two approaches to preventing this type of accident.
1. Provide a wing leveler function in Alt 2 law so the PF doesn't have to touch the stick except to maneuver. (The lowest common denominator approach)
2. Emphasize basic manual instrument skills under worst case conditions during recurrent training e.g. flying the S-1 and S-3 basic instrument patterns (by hand of course) at altitude in Alt 2 law. (You can always ask to try flying this just to prove to yourself that you can still do it.
)
I am hoping the regulators mandate the second approach.
Understood, and your approach (1) would have a similar result to my thoughts about a "pitch lock" i.e. the pilot would not have an opportunity to inadvertently change the pitch when controlling the roll, as he/she wouldn't need to control the roll either when the AP disconnected, with that "wing leveler".
My concern about approach (2) is that, while it is much preferable and I am all for pilot training for hand flying, it's different in the shock of an emergency. As someone else here said, a sim or training session where you know you're going to get emergencies thrown at you, or where you know you're not going to get them thrown at you, cause different human responses than a nighttime flight at FL350, with no warning that those emergencies are about to happen. Therefore can we really rely on approach (2), without
also having some additional help (like approach (1))?
This type of situation where humans don't take over very well from a "monitoring" role, was discussed in a paper by Dr. Lisanne Bainbridge called "Ironies of Automation". Well worth a read, for those who haven't, IMHO. I'll try to find a link... This isn't specifically a piloting problem; it's a human problem and has also been seen at nuclear power stations etc.