"Ron Garret" wrote in message
...

If an aircraft enters an unusual attitude following an AI failure, most
pilots would say that that accident was caused (at least in part) by the
AI failure despite the fact that the AI didn't (directly) cause the
plane to enter an unusual attitude.


I think you're wrong about that. I think most pilots would say that
erroneous information provided by a failed AI would be a direct cause of an
unusual attitude. Are you a pilot?



But OK, have it your way: the pilot drops the GPS. Being a competent
pilot he does not attempt to retrieve it. It bounces around in the
turbulence and, unbeknownst to the pilot, it gets wedged under one of
the rudder pedals. The airplane spins and crashes turning base to final
because the now limited travel on the rudder pedal makes it impossible
to adequately compensate for adverse yaw (and the pilot doesn't realize
it until it's too late).


So what you're saying is that loose objects in the cockpit can be hazardous.
That may very well be, but that's not the subject of this discussion.



Most accidents, including this hypothetical one, are the result of long
causal chains of events, all of which are collectively necessary for the
accident to occur. It is true that the pilot in my first scenario was
incompetent, but in a way that would not have manifested itself but for
the need to retrieve the GPS from the floor of the plane. (And this, by
the way, is why it matters that it's a GPS that was dropped and not,
say, a granola bar. The perceived urgency of retrieving a granola bar
would probably be less than that of retrieving the GPS.)


Why? The pilot can always ask ATC for navigational assistance, but they
can't provide an inflight snack.



It's a moot point since I have now provided a scenario involving a
competent pilot, but do you have a principled basis for assigning all of
the causality to one of many factors in the causal chain, or did you
simply choose to make this assignment arbitrarily in order to support
your untenable position?


My untenable position? It is my position that use of a handheld GPS for IFR
enroute navigation in US controlled airspace is without hazard. Note that
nobody has identified any hazard from such usage.