IFR with a VFR GPS

"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.

In article et,
"Steven P. McNicoll" wrote:

"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.

I don't really want to quibble over terminology. The fact of the matter
is that a failed AI is neither necessary nor sufficient to produce an
unusual attitude. (To produce an unusual attitude you must have either
erroneous control input, extreme turbulence, or structural failure.) An
AI failure is nonetheless considered a risk. Likewise, a failed GPS is
neither necessary nor sufficient to produce CFIT. It is nonetheless a
risk. The two situations are exactly analogous. They differ only in
the degree of risk.

Are you a pilot?

PPIASEL with just over 500 hours. I fly an SR22. I have also in the
past flown IFR in a 182RG/A both with and without a handheld GPS (yoke
mounted) and felt a lot safer on the whole when I had it than when I
didn't.

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.

It is if the loose object in question was a handheld GPS being used for
enroute IFR navigation yada yada yada.

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.

That's why I hedged with "probably." Different pilots assess situations
differently. I can actually envision situations where retrieving a
granola bar might have a pretty high priority, but that, as you say, is
not the topic under discussion.

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.

You can keep insisting that, but the fact of the matter is that I have
now described two (or three depending on how you count) potential
hazards from such use. So yes, your position that such hazards do not
exist is untenable. You can argue that the risks are insignificant (and
I would agree, and so, I think, would everyone else) but you can no
longer argue that they do not exist without behaving like -- dare I say
it? -- an idiot.

rg

"Ron Garret" wrote in message
...

I don't really want to quibble over terminology. The fact of the matter
is that a failed AI is neither necessary nor sufficient to produce an
unusual attitude. (To produce an unusual attitude you must have either
erroneous control input, extreme turbulence, or structural failure.) An
AI failure is nonetheless considered a risk. Likewise, a failed GPS is
neither necessary nor sufficient to produce CFIT. It is nonetheless a
risk. The two situations are exactly analogous. They differ only in
the degree of risk.


Well, Ron, the fact of the matter is a failed AI is quite sufficient to
produce an unusual attitude.



PPIASEL with just over 500 hours. I fly an SR22. I have also in the
past flown IFR in a 182RG/A both with and without a handheld GPS (yoke
mounted) and felt a lot safer on the whole when I had it than when I
didn't.


Was any of it logged in the US? Was any of it logged outside of MSFS?



It is if the loose object in question was a handheld GPS being used for
enroute IFR navigation yada yada yada.


So you're saying the hazard presented by use of a handheld GPS for enroute
IFR navigation in US controlled airspace is loss of rudder control. Is that
correct?



You can keep insisting that, but the fact of the matter is that I have
now described two (or three depending on how you count) potential
hazards from such use. So yes, your position that such hazards do not
exist is untenable. You can argue that the risks are insignificant (and
I would agree, and so, I think, would everyone else) but you can no
longer argue that they do not exist without behaving like -- dare I say
it? -- an idiot.


Right. You said use of a handheld GPS for IFR enroute navigation in US
controlled airspace is hazardous because it could compel the pilot to turn
off all his other avionics or jam the rudder pedals. And you think me an
idiot because I try to explain why that isn't so.

You're flying the airways of life with a couple of props feathered.