Altimeter Calibration Height

I agree that it measures pressure and that the indicated altitude is based
on calibration. I agree that it could be calibrated for the bottom, mid, or
top of the plane (for whatever it would matter). Personally, my altimeter
was calibrated sitting on a bench with no regard for the difference in
height between the landing gear, the static port, or the position of the
altimeter.

From a purely theoretical view, I don't think you can say that an altimeter
measures pressure at the location of the instrument. It's a closed system to
the static port. While the pressure inside the tubing will respond to
elevation changes similar to the open atmosphere, there is a difference.
Admitedly, the difference over the height of an aircraft is insignificant.
But stretch that tubing to a low pressure system in the next state and your
altimeter will defininetly not be reading the local pressure.

The question remains, are big airplane altimeters calibrated to account for
the distance between the landing gear and the instrument. Someone else asked
about when setting the altimeter based on field elevation rather than by
Kollsman setting. Another way to ask the question is, "When setting the
altimeter to field elevation in a tall airliner, how close is the Kollsman
value to the local barametric pressure?"

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Travis
Lake N3094P
PWK
"Jose" wrote in message
. ..
In other words, an altimeter indicates altitude at the level of the
instrument itself.

No. The altimeter senses pressure at the level of the instrument itself.
It indicates altitude depending on its calibration and kollsman setting.

Jose
--
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