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> Many people have mentioned standby vacuum as essential for IFR operation.
> While I agree with the reasoning, I think the conclusion is somewhat
> flawed.  Since the fact is that if you lose your AI in IMC you will
> probably die, I plan to install an electric AI as a backup to the vacuum
> driven instruments.  Having a vacuum gyro and an electric gyro means that a
> single failure can't take them both out.  True paranoia might actually lean
> towards a separate backup battery for the electric AI, to account for
> simultaneous vacuum and electrical failures.

My current backup vaccuum is electrical.  It was about $200-300 if I recall (not 
including the install fee (irrelevant here).  It senses low vaccuum and kicks on 
automatically.  Made by Precise-flight.  I've always wondered though how I could 
tell if the electric system was running the AI or if the backup was.

Incidently, I have had a vaccuum failure in IMC, and am still here to talk about 
it. (in a plane without backup) Apparently, all the partial panel work pays off. 
For those not instrument rated, using combinations of Turn and Bank, VSI, DG and 
Airspeed Indicators substitutes for the AI.  Not recommended in any event!

XLRG (somewhere further West than West of Texas as previously reported)