Backup gyros - which do you trust?

Dan and others

Full panel makes it easier for a qualified pilot to fly IFR. I doubt
a properly trained pilot is over whelmed by task saturation. There may
be lots of guages in the cockpit but only a few are included in your
primary scan on IFR.

How many pilots today practice partial panel and can fly it when
required? Not many I'd say. Never hear it discussed in any avation
groups any more as failure rate of gyro's is very small..

With single or dual gyro flight instrumnts and the problem of knowing
which one to believe all you have to do is check your partial panel
instruments to identify the correct gyro.

All of this takes understanding of IFR flying and partital panel
practice anticipating a gyro failure. Instrument (gyro) failures are
emergencies that can kill you if not proficient on partial panel.

How many GA pilots today could make even a NDB approach partial panel
much less a ILS or GPS approach?

Many areas of flyng have high risk. One can only try to stay ahead of
the airplane (and system) to reduce risk.

Fly safe and a nice day to all.

Big John



On Sun, 13 Jul 2003 07:35:24 -0500, "Dan Luke"
wrote:

"Steve House" wrote:
I've been reading with interest the several threads where a number of
people
have strongly pointed out the advantages of a backup electric AI to
supplant
a vacum driven main AI. But I'm reminded of the saying "A man with a good
watch always knows what time it is. A man with two watches is never
sure."

This is a very interesting issue, to me. Reading the records of IMC
loss-of-control accidents is very unsettling to this single pilot IFR flyer
because of the cases where there *was* backup attitude instrumentation
available. Even when there wasn't, the pilots usually had at least the turn
coordinator to help keep the aircraft upright. It is too simple to chalk up
all these accidents simply to lack of proficiency. There is something else
going on - some human factors issue that has not been properly identified. I
suspect it may be related to task saturation. If so, instrument panel
clutter could be a contributing factor.

So I'm toodling along in IMC with no outside horizon reference and I see
my
two AIs don't agree with each other. How do I determine which to trust?
If
I had a third, I could go with a 2 of 3 voting strategy of course, but
with
only two, what do you do to decide which is operating properly and which
one
has faulted? Obviously I can look for consistency with other
instruments -
does my DG or Turn indicator show I'm turning, does the VSI show a climb
or
descent - but what would be the best strategy given the various ways
vacuum
or electric driven instruments can fail?

My strategy is to include a yoke-mounted GPS displaying a synthetic HSI in
my scan. This works wonderfully well in training, but I am not sure how well
I would do in a real situation where my AI suffered a gradual failure.