backup for vacuum pump/attitude indicator failure

Just a little story about flying with failed instruments.

I was flying with an instrument student, and had been telling him the
importance of the gyroscopic instruments to maintaining control of the
airplane in the clouds. So I covered up one gyro, he kept flying along
fine. He was under the hood, we were flying mostly straight and level,
maybe some simple level turns, don't remember all the details now. Then I
covered up the second gyro. He kept flying along fine. So I covered the
third gyro, expecting him to soon wind up in a spiral dive. He kept flying
along fine. So finally I asked him how he was doing it. I had forgotten
about the GPS. He was watching the TRK number on the GPS, and that was
giving him essentially the same data as the DG, although with a slower
update rate. Along with the pressure instruments, he was doing just fine.




"Kelly" wrote in message
ups.com...
I would be interested in getting opinions about backup systems for a
vacuum pump failure and/or AI failure. I have a 172P with a single
vacuum pump system, standard instruments otherwise, and a Garmin 430.
I am most concerned about having a good backup if I lose a vacuum pump
or AI in IMC. I have been thinking about either a Garmin 396/496 or
the electric AI available from Sporty's. Looks like I could get a 396
or installed electric AI for about the same price ($2200 or so). While
I haven't seen the panel page/"6-pack" page on the 396 or 496, I have
read (in Aviation Consumer) that it's good enough to keep control of
the airplane in an emergency situation. Obviously, the 396/496 has a
number of other neat features such as inflight weather, terrain info,
etc. Any suggestions on which way to go with this.

BTW, I had also considered the Precise Flight backup vacuum system for
a while, and it certainly is cheaper (around $700 installed). However,
I was concerned by the fact that it would do nothing for you in the
event of failure of the AI vs. the primary vacuum pump.

Thanks.
Kelly