From: utzoo!decvax!harpo!npoiv!alice!danny
Newsgroups: net.aviation
Title: Re: IFR insurance low cost
Article-I.D.: alice.1420
Posted: Wed Jan 26 12:46:04 1983
Received: Fri Jan 28 21:30:11 1983
References: ihuxr.295 avsdT.271 ihuxa.180 alice.1418 ihuxa.182


I certainly agree with Jeff Williams that altimeter failure in flight
is not likely (tho I've read about a cupla such incidents).  There
are several radios/instruments that I would give higher priority to
as far as back-ups for IFR flight are concerned.  However it is a 
fact that the altimeter is probably the simplest and cheapest to
back up.  And considering that we're only talking about accuracy to
within a few hundred feet, venting into the cabin is no problem
(and having passed the instrument written, we know in which direction
it'll be off, right?).  I've flown with an (aircraft-type) altimeter
sitting in my lap not connected to anything and it agreed with the
panel-mounted static-port-vented instrument within about 100 ft.
Imagine flying a C172-type aircraft in IMC in an area of 5000' peaks
and sufferinf an altimeter failure.  Having a back-up that told you
your altitude to even within a THOUSAND feet would be highly welcome.
(Cabin-venting of course assumes an unpressurized cabin.)