Hello All,

There has been much discussion here about the obvious benefits of
redundant systems, engines, vacuum, electrical etc., when flying in IMC.
We've also read NTSB reports of crashes of very well equipped planes
where the pilot did not make use of redundant instruments.
As for myself and perhaps others, I will most likely never have access
to any aircraft with system redundancy beyond the simple electric
TC/vacuum gyro combo. I fly singles such as the 172 and 182, all
usually at least 25 years old. I did however, obtain my ratings for the
purpose of going places and doing things, and I seem to be flying about
5% of my hours in actual IMC. Being a person that places a high value
on my own ass, and the asses of the people who fly with me, like others
here I carry some backup equipment. A Magellan 315 I have flown 24,000
miles with so far, a JHP-520 portable com, Palm VII/CBAV for weather, and
spare batteries for all. For now I fly well maintained rentals.

So far in my meager 400 hours I have experienced a total electrical failure,
an AI failure, and a few VOR and ILS problems. All these were easy to
work around. I'm satisfied that with a vacuum failure I can fly just fine
on the TC, and vice versa. How about when you lose your vacuum
instruments *and* your electrical system? No nav, no com, no gyros
at all, just your engine and pito-static instruments. The essence of
maintaining control in IMC is being able to determine if you are turning.
I've long figured that even with a 1 second position update rate, the
simplest GPS should give you enough turn data to stay in control
in addition to guiding you to an airport and making a useable approach.
I and iron-gut acro/safety pilot Doug found out yesterday.

Conditions:
Clear, 92 degrees, fairly rough thermal TB about 2000 agl. For warmup,
we did 2 full hours of currency approaches and holds, building a
"pyramid" of stress and fatigue.

The task:
"Fail" all gyros, AI, TC, DG, and all nav equipment. Trying this for the
first
time ever, now navigate 25nm to an airport and make a successful
non-precision approach using only the handheld GPS, the "ball", and
pito-static instruments.

My strategy is to make good use of the inherent stability of the 172,
keeping my hands off the yoke as much as possible and turning with
the rudders. To keep things simple, I plan only 2 turns. The GPS is
simply set for a "go-to" to our airport. Our destination was to
the northwest, so fly due west a while, then 45 to the right to
intercept a long final approach course. The GPS display mode was
a simple numbers-only bearing/heading/distance/speed. Right off the
bat it was very strange and we thought our test might be over in about
1 minute. The GPS, though updating every second, is still giving you "old"
information. Now using the rudder to turn, the airplane takes a while
to respond. With the constant upsetting influence of the thermals, the
plane is always wanting to turn. You see it on the GPS, and by the time
you get some rudder pressure on, you are maybe 10 to the right. Now
you hold the rudder and wait for the plane to respond, and slowly you
come back on course, but overshoot. I try to adjust my inputs to smooth
things out but the TB makes it pointless. I resign myself to the fact that
at best we will make constant small s-turns all the way. Every now and
then a good thermal jolts us into a significant bank. My instinct was to
get the ball centered, check our pitch with the airspeed etc, then check
the GPS to see which way we were now going and slowly urge us back.
Seems to work. Soon I realize we've gone several miles already, and all
this actually seems to be working! Patience seems to be the rule- put a
small amount of pressure on the rudder, hold and wait for results.
Soon we are intercepting our 8 mile final approach course, using a
published NDB approach as a template, and doing our altitude
stepdowns based on GPS distance to the field. Closer to the ground
thermal induced turns made it difficult to get down to MDA as soon
as I would have liked, but we did arrive at MDA right over the field and
a circle to land could have been easily done. In spite of the constant
s-turning, we maintained our final approach course within +- 3 degrees,
better than I could have done with the ADF and the full panel!

We finish up with a partial panel ILS into our home field, and hot and
tired, I manage an embarrasing multi-bounce landing. The conclusion
of course, is that a battery powered GPS is an absolutely essential
piece of backup equipment that can save you even with major system
failures. We did a worse case scenario, but for example, you could use
the GPS to simply hold a course to VFR conditions. At higher altitude
you would have a smoother ride needing only occasional control input.
We must, in an emergency, actually remember to use the backup info
available whether from a portable device or a panel instrument.

Anyone else tried this type of emergency procedure?
Thoughts? Tips?

Tom Pappano, PP-ASEL-IA

ps: Howard Stark's 1-2-3 Method of Blind Flying was Needle-Ball-Airspeed.
This could be the 4-5-6 method: GPS-Ball-Airspeed