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Article: The dangers of GPS altitude.(Global Positioning System)
- Article from:
- Combat Edge
- Article date:
- May 1, 2007
- Author:
CopyrightCOPYRIGHT 2007 U.S. Department of the Air Force. This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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As aviators, we rarely think about the accuracy of our instruments. When you look down at your airspeed indicator and see 200 KIAS, unless you have a specific reason to doubt the equipment (icing, etc.), you can reasonably assume that the aircraft is moving at 200 KIAS. When your VVI tells you that you're descending at 300 feet per minute, that's pretty much exactly what your plane is doing.
But what about altitude? When you look at your altimeter and see 10,000 feet MSL, what exactly does that mean? Obviously the altitude that you're reading is a function of your altimeter setting. If in class A airspace with 29.92 properly set, your true altitude might be off ...