Ryan Ferguson wrote:
Sydney Hoeltzli wrote:
I think it is well worth reading, especially for those who
seem to feel the tach and the T/C are superfluous.

I read it. I don't really get anything from it which would apply to the
turn coordinator versus AI discussion of late.

Oh, well.

The author uses some
terminology rather loosely - referring to pressure instruments and
including in the list (I think?) the DG and AI.

No, I don't think so. He states seperately that his vacuum instruments
tumbled, and gives the reason. Then he assumes the reader remembers
this, later on.

It's not clear to me
how or why he lost his vacuum driven gyros from the story as posted.

Really? It's clear to me. He was flipped inverted, and his gyros
tumbled. Are you sure you read it?

I
also think he might have derived some erroneous conclusions from his
close encounter - for example he referred to engine noise as the 'best
guide to inversion.' Sure, engine noise can be helpful for determining
whether the airplane is in a dive or climb, but it might be doing either
while inverted and the pilot may not know.

I think you missed the point, which is to correlate engine noise
with yoke movement. If you pull back the yoke to climb, but engine
noise increases, what does that tell you? If you push forward
on the yoke but engine noise decreases, what does that tell you?
(recall we're talking fixed pitch prop here)

If your gyros tumbled because you flipped inverted and your pressure
instruments were temporarily unreliable because of massive pressure
changes, what would you suggest as the "best guide" to determining
if you're inverted?

Like others in the aforementioned thread, I take attitude information
pretty seriously. I fly two vacuum pumps and two AIs. Both AIs are
air-driven. My system vulnerability is my plumbing, which I accept as a
reasonable risk.

Have you tried what Big John suggested, taking the AIs loose from
the panel and seeing if/when they tumble, and when (after how much
banking and diving) they develop sufficient error to be problematic
as guides?

If one is more susceptible to spatial disorientation from looking at a
wider swatch of panel real estate, one needs to fly with an instructor
or safety pilot until they're able to handle it. I regard these things
as basic requirements to fly instruments.

Hmmmm...if the issue of having to turn one's head frequently is
just a proficiency thing, Ryan, and any pilot ought to be able
to handle it if he flies with a safety pilot enough -- why do
some experienced pilots stress that the scan should involve just
moving the eyes, not the head?

Why do physiologists stress that rapid head movements are a good
way to induce spatial disorientation?

In line with this thinking, my personal feeling is that the location of
the indicator may not be the culprit. The problem more likely is the
ability to modify one's actions to properly react in an emergency such
as vacuum or attitude indicator failure in IMC. (And yes, I will always
call that an emergency, regardless of how comfortable one may be flying
partial panel.)

Can't argue here. Anything which bites so many pilots who "ought to
be able to handle it" for reasons which are unclear at present,
deserves to be handled like a live viper IMHO. Carefully, and with
all available precautions.

I think people that lose their cool in recoverable
emergencies will tend to break airplanes regardless of how their
instrument panel was laid out.

Can't argue with that, either. OTOH, I do think that it's too
simple to dismiss some of the problems supposedly good, experienced
pilots have as entirely due to lack of proficiency, unless one has
solid evidence that this is the case.

One other side note. You mentioned that the tach should be located
where it can be part of the primary scan.

Um, not exactly. I say one should consider this experience when
deciding whether one wishes to relocate the tach outside one's
primary scan.

In the Twin Comanche, almost
all of the ships flying have MAP and RPM on the copilot side of the
panel.

If you'll pardon my pointing this out, I do think a plane with an
adjustable pitch prop has different issues for power management.
I notice this when I let pilots who are used to same take the
controls of my plane.

Cheers,
Sydney