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Re: altimetry



plus 70 feet of friction if you've been descending at 750 feet
per minute, plus installation error, .....


I have one that has a vibrator (50 feet resolution) -- I worked for
someone who patented a meter (d' Arsonval) tapper.

bc who still morns his rather accurate and precise altimeter and
occasionally uses a meter that sticks.


"John S. Denker" wrote:

Hugh Haskell wrote:

FAA requires every aircraft to have a
"sensitive" altimeter ..... By sensitive, IIRC, they mean capable of detecting altitude
changes of +/- 10 ft.

A "sensitive altimeter" is only required for IFR.
Otherwise a generic "altimeter" will do.
http://www.risingup.com/fars/info/part91-205-FAR.shtml

But I've never seen an altimeter that wasn't designed
to IFR specs.

They must also be adjustable to the local sea
level barometric pressure, and when so adjusted they read height
above sea level, to be certified for use, I think they have to be
within +/- 20 ft. when within about 2,000 ft of the ground

Oooh, it's !!much!! worse than that. It could be off by 30 feet
out of 2000 during a bench test, and the test might have not
have been done very recently, and then there could be hysteresis
plus 70 feet of friction if you've been descending at 750 feet
per minute, plus installation error, .....
http://www.risingup.com/fars/info/part43-E-APPX.shtml


cut