On Fri, 11 Jul 2003 01:18:39 GMT, "Peter Kovari"
wrote:

.I merle find that maybe these tolerances I experienced were
excessive, apparently some of you have experienced the same.
Over and out. Peter K

They weren't. They are about what you would expect and the difference
between Pressure altitude and GPS altitude readings is completely
explained by the physics of what you are measuring in each case.

GPS altitude is accurate to 50 feet most of the time. Allow +/- 100
feet and you have it nearly all the time.

Pressure altimeters are of similar order of accuracy but measure
PRESSURE ALTITUDE which is a different physical entity from GPS
altitude and the numbers you get may or may not be the same as GPS
altitude.

Mike Borgelt