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[OT] altimeter calibration?
I know accuracy varies based on uncontrollables, but I wonder if this
can be done via GPS? At least for the calibration part, you do not want
to deal with a jammed signal while in action.
Jean-Claude
84 8v
Rave Racer 77 a ?crit :
>
> I've never heard of altimeters being set by using radar to measure
> distance over ground but it might be possible. The way light aircraft
> and older large aircraft do it is by measuring static air pressure and
> comparing that to a Mean Sea Level pressure setting that you can
> adjust on the altimeter. 29.92 inches of Mercury is standard
> atmospheric pressure. Inches of Mercury (in/HG) is how all of my
> altimeters were measured. If you're on the ground at 1000ft above sea
> level and your local pressure is 29.92 then you should read 1000ft on
> your altimeter. If you know your altitude when you hop in the
> aircraft then you can find you current pressure by adjusting your
> altimeter to your local altitude and reading the pressure
> measurement. There are local stations all around the country based at
> small airports, navigation aids and other beacons that transmit a
> recorded weather message that gets updated regularly. This is a good
> place to get your pressure if you're in an unknown area in
> uncontrolled airspace. When you get above a certain altitude, I think
> 10,000ft, you're supposed to set your altimeter to standard
> atmospheric pressure so that everyone is using the same basis for
> measurement. This is more for commercial aviation to avoid large
> differences in pressure settings on long distance flights where two
> aircraft may think they have altitude separation but don't because of
> the different pressures at different points of departure. Hope that
> helps.
>
> Rave Racer
> Current:
> '91 Jetta GLI 2.0L 16V
> '81 Scirocco Mk1 1.8L 8V Digifant 2
> '86 Fox
> 2 GTI parts cars
>
> Gone:
> '89 Jetta 1.8L 16V GTX
> '87 Audi 4000 Quattro
> '72 Triumph GT6