(Nathan Young) writes:

1. Vacuum failure -- no immediate, direct benefit from the handheld
GPS.

I disagree for several reasons. Many GPS models have the ability to
partition the main display and show an 'HSI' and groundspeed in
addition to the moving map.

That could be a nice indirect benefit, but the danger is ending up
with yet another distraction. The GPS pseudo-HSI display is much
easier to interpret but lags dangerously, while the TC and ASI are
harder to interpret but have minimal lag. I'd be nervous that in an
emergency my eyes would be drawn too much to the false security of the
GPS pseudo-HSI display instead of where they should be, on the TC and
ASI.

This information is very valuable as a cross-check to the flight
instruments.

Agreed, but I don't think I'm a good enough pilot to use it safely in
a partial-panel situation, where I'm already under a great deal of
stress. I'd probably keep the GPS just on a basic navigation display,
and even then, only if I wasn't able to talk to ATC. My preference
(of course) would be vectors with nice shallow no-gryo turns, so all I
had to worry about was basic flying.

In IMC - I'll take any clue available that indicates something is
wrong with the gryo instruments. I'm confident I can fly partial
panel, but detecting the failure mode is the difficult part...

My only vacuum failure so far was in night VMC, but it was impossible
to miss the big orange annuciator light right above the altimeter --
even my passenger saw it immediately. I never thought of the
importance of having altimeter/oil/vacuum annunciators inside my main
scan when I was shopping for planes, but I'm certainly glad now that I
have it in my Warrior.

Of course, the best insurance is just keeping all the primary
instruments in your scan. Annunciator bulbs can burn out (though I
test them in every preflight).

I have flown approaches under the hood with reference to only the GPS
(this is in a PA28 which is a reasonably stable aircraft). While not
easy it is do-able as long as the plane is trimmed before the approach
and control inputs are kept minimal.

How rough was the air? I wouldn't mind trying it in nice, smooth
stratus or even in light chop, but I wouldn't have wanted to count on
it in some of the cumulus I was flying through this weekend.

Regarding the distraction of setting up a GPS upon the failure. I
think it is significant. I've had a similar situation - an electrical
failure at night (fortunately in MVFR conditions). This was in class
D airspace. Tower called and let me know they lost the transponder.
When I keyed the mic to transmit, the panel went black. This happened
directly over the field. By the time I got the flashlights setup,
grabbed the handheld radio (backseat), plugged in the headset, turned
on, tuned in, and let tower know what was going on - I was 5-6 miles
North (about 3 minutes in the Cherokee).

If or when I'm ever in an emergency, I won't appreciate being
second-guessed afterwards, so I'll try not to do that now, but I do
like to learn from people who have been in real emergency situations.
At the time, what was your motivation for plugging in the handheld,
etc., rather than just landing NORDO? Would you make the same
decision again?

The workload during these few minutes was relatively high.
Significant enough that I revamped how I approach IFR flying. I do
not fly hard IFR at night, and I always keep the handheld charged and
ready to go in the side pocket.

I'm starting to wonder if my handheld was worth the money, since its
transmission range is so small without an external antenna. I'm
thinking of getting a pass-through cell-phone headset adapter instead,
since I'll be able to reach help much quickly (and can keep ATC and
FSS emergency numbers on the speed-dial).


All the best,


David