cecil e. chapman

I've been doing quite well with my instrument flying lessons and a couple of
the approaches, yesterday, we found ourselves in IMC (which we notified
Norcal approach about whom we were in communication with that was providing
us radar coverage and vectors into the approach). When my instructor saw
the IMC coming (fog layer) he took the plane briefly and told me to take-off
the foggles, I did,,, and then I had the plane. Well, as I entered the real
IMC I noticed that my turn coordinator was indicating a turn to the left and
yet when looking at the attitude indicator I PERCEIVED that it was showing a
turn to the right. I even mentioned to my instructor when he pointed out
the left turn that I felt my AI and turn/bank indicator were contradicting
each other, but he assured me that they were fine. I guess that is the only
part of yesterday that really is bugging me, because I can't figure out why
I would have this experience when I've been doing nothing but instrument
flying (under the hood) just fine (with plenty of turns, etc..). Why should
I have had this momentary 'brain freeze' just because I was looking at
actual IMC instead of the frosted 'IMC' from the foggles? What about the
experience made it different? How does this 'confusion' happen and how can
I absolutely prevent it from ever happening again? Understandably I found
it most unsettling as this kind of perceptual error is what leads pilots
into making the graveyard spiral out of a cloud

By the way, here's a quote from a question asked of Rod Machado, that I
found this morning, which speaks to the brief experience that I had:
"...I'm instrument rated with 1,500 hours. As I entered the clouds I went
on the gauges. No problem, right? Wrong. I perceived the turn coordinator
to show a left turn and the AI showing a right turn..." This describes what
I experienced, yesterday (briefly) to a 'T'..... but my question to the
CFI's out there is, "Why?". I guess I'm asking so that I can correct
whatever error I made that lead to the brief moment of apparent
'contradiction'. If I've been flying, turning, etc. under the foggles just
fine what about the experience of going IMC for real can create the
problem/perceptual error that I described?

--
--
Good Flights!

Cecil E. Chapman, Jr.
PP-ASEL

"We who fly do so for the love of flying.
We are alive in the air with this miracle
that lies in our hands and beneath our feet"

- Cecil Day Lewis-

Check out my personal flying adventures: http://www.bayareapilot.com

gary l. drescher

A typical AI has a white line designating the horizon. It looks a lot like
the white line designating the aircraft on the TC. So if you look hurriedly
from the TC to the AI, you might construe the AI's white line the same way
as the TC's, in which case the TC's turn will seem opposite the AI's bank.

Hoods usually leave you with some peripheral-vision cues as to your
orientation (or at least as to whether your orientation is changing).
Maintaining your aircraft's attitude in IMC, without those cues, is a harder
task to which you're less accustomed. Anything that makes flying hard also
promotes all sorts of errors, including the perceptual error you noticed.
Just practice more in IMC. --Gary

bob gardner

Don't look at the horizon line to determine direction of bank, look at the
indicator at the top of the instrument...it always points "up." Some texts
call it the sky pointer.

Bob Gardner

maule driver

"Cecil E. Chapman" <bayareapilot@sbcglobal.net>


can


I don't know but it seems part of the whole pile of stuff that makes taking
off into a low ceiling one of the most challenging parts of a flight in
actual. The transition from rolling on the ground, to visual rotation, to
instruments in the climb is one of the most disorienting for me. Getting my
mind to understand that the instruments are all showing the same thing at
that moment can be challenging - especially with shadows on the ground
flickering by at the same time.

What Bob says about using the sky pointer is good stuff. Gotta try focusing
on that one.

dan luke

Hey! That's a good one!
Never heard that tip before; thanks, Bob.
--
Dan
C172RG at BFM

cecil e. chapman

like

hurriedly


This was what I did EXACTLY,,, thank you!!!!

--
--
Good Flights!

Cecil E. Chapman, Jr.
PP-ASEL

"We who fly do so for the love of flying.
We are alive in the air with this miracle
that lies in our hands and beneath our feet"

- Cecil Day Lewis-

Check out my personal flying adventures: http://www.bayareapilot.com

roy smith

I don't know the whole history of how the instruments were designed, and
how much was known about human perception and ergonomics at the time,
but I think they got one of the instrument backwards. Of course, it's
way too late to do anything about it now.

As you roll into a left turn, the AI rotates clockwise, and the TC
rotates counter-clockwise. The difference is that the AI is showing you
what the horizon looks like from the point of view of a pilot looking
out the front window, while the TC shows you what the plane looks like
from the point of view of an observer behind you.

To an experienced instrument pilot, this is perfectly natural. You look
at the AI and think "left turn". You look at the TC and think the same
thing. But, I remember my very first flights, being confused as to why
the two instruments were apparantly showing opposite motions. My guess
is this is what happened to you.

greg esres

<<I meant the little airplane that is part of the same instrument, so
to speak, which indicates rate of turn.>>


So did I.

The "little airplane" registers YAW, not BANK.

And I don't mean sideslip. In a perfectly coordinated 360 degree
turn, the aircraft YAWS 360 degrees.

roy smith

Actually, the little airplane registers a mix of yaw rate (not "yaw",
but "yaw rate") and roll rate, weighted about 2:1 in favor of yaw rate.

greg esres

<<Actually, the little airplane registers a mix of yaw rate (not
"yaw", but "yaw rate") and roll rate, weighted about 2:1 in favor of
yaw rate.>>

Excessive detail obscures the point.

(And in a level, constant bank, there is no roll, so it's pure yaw.
OK, yaw rate.)