From: steve@netcom.com (Stephen Williams)
Subject: Re: Stay off the rudder!
Organization: Organizations Anonymous
Date: Tue, 6 Oct 1992 03:34:36 GMT

In article <1992Oct5.200118.18558@ee.rochester.edu> dela@ee.rochester.edu (Del Armstrong) writes:

>>- Is it generally considered possible to fly IFR with just airspeed,
>>  altimeter and a compass?

In article <1992Oct5.231603.24358@porthos.cc.bellcore.com> patter@dasher.uucp (24224-guthrie) writes:

>In an open cockpit, yes but very difficult. In a cabin aircraft, generally no.

I would tend to disagree here. Airspeed and altimiter can be used
to controll pitch, and the compass for controlling bank. Yaw can
be controlled by the feel of transverse forces. (Sliding left or
right on the seat.)  In reality, however, the gravitometer doesn't
often fail, even if the turn-bank indicator does.

>All IFR pilots are required to do some training with the vacuum instruments
>out (this usually means with the attitude indicator non-functional). It
>is possible to use the needle and ball as an attitute indicator (but *I*
>can't do it). I would suppose that the magnetic compass could help a
>little, since it tilts to one side when you bank. You'd have to be very
>precise.

Attitude indicator and DG are typically vacuum powered so can fail
together, and this is how the partial panel excercises go. Also,
the instructor, during training will "fail" the vacuum instruments
then ask you to recover from some unusual attitude. After all, in
real life this is how you DISCOVER that those instruments have failed.

The tilt of the compass is NO HELP AT ALL, unless your foot-work
is off. If you coordinate turns the gravitometer (which is a level)
points down because all g fources are "down." The compass, which
floats, behaves the same way. (Compass errors in a turn are fodder
for another thread.) Of course, I suppose that poor yaw controll
can be detected this way: step on the rudder opposite the tilt of
the floating compass. Hmm...

>Leaving out the engine instruments, the basic VFR instruments are 1) magnetic
>compass, 2) heading indicator, 3) turn & bank indicator, 4) attitude
>indicator, 5) altimeter, and 6) rate of climb meter (did I miss any in
>there?). With these your typical private pilot has the ability to execute
>a 180 degree turn quite safely. That's basically what they recommend.

FAR 91.205(b), VFR day required instruments:
	(1) Airspeed indicator
	(2) Altimeter
	(3) Magnetic direction indicator
	[ ... sundry engine instruments ... ]

FAR 91.205(c), VFR night, add these:
	(1) approved position lights
	(2) ... etc and other lights and electrical gizmos.

FAR 91.205(d), IFR, add these:
	(1) 2-way radio
	(2) Gyroscopic rate-of-turn indicator [with a few exceptions]
	(3) Slip-skid indicator [gravitometer]
	(4) Sensitive altimeter adjustable for barometric pressure
		[ Note that for VFR ops the altimeter can
		  be "insensitive." ]
	(5) A clock displaying hours, minutes, and seconds
	(6) Generator or alternator of adequate capacity...
	(7) Gyroscopic pitch and bank indicator (attitude indicator)
	(8) Gyroscopic direction indicator [ This in addition to the
		magnetic direction indicator. ]

Notice that VFR flight doesn't require much, instrument wise. Also note
that the FARs make no mention of the VSI (rate of climb indicator) However,
I frankly have never seen a plane without most of the above equipment.
(Ok, so I fly complex aircraft.)

>Well, you're one rating up on me. All I know about IFR is what I've
>read. As far as I can tell, it's all done with mirrors. 

More or less:-) 

>By the way, you really ought to consider joining AOPA. The magazine
>alone is worth the money.

Yep.

>Oh - one more thing. "Continued VFR into IFR conditions" is one of the two
>top causes of death in the air world for us little guys.

Instrument rated pilots can (and do) get killed this way too. IMC
flight requires PREPARATION. (I hesitate to say "planning" because
few fright plans survive ATC computing facilities undamaged:-) Be
prepared.


--Stephen Williams
PP-AMEL-IA