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Question
Dear Paul

Do the altimeter Flight instrument indicates with accuracy the plane Altitude from the ground level to the pilot?.

How does the Altimeter instrument measure the Altitude?.

Thanks
Prashant

Answer
The usual aircraft altimeter measures atmospheric pressure from which altitude is deduced from the fact that pressure decreases with altitude in a known way. There are mathematical models that relate pressure with altitude in a standard atmosphere. However, atmospheric pressure changes with temperature so temperature fluctuations will introduce errors. The weather, in other words, becomes a factor. There is also the problem that the pressure port on the aircraft may be affected by flow effects or ice.

Radar altimeters that reflect a signal off the ground are much more accurate, but expensive and used in advanced commercial and military aircraft. GPS systems can also be used using satellite data, but accuracy is a problem.

Aeronautical Engineering

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Paul Soderman

Expertise

Aeronautics, Aerodynamics, Fluid Mechanics, Aeroacoustics, Noise Control, Muffler Design, Wind Tunnel Research.... I know nothing about India - do not ask about schools, jobs, application requirements, career choices, etc. for India. Please, no text message verbiage; I prefer full words in full sentences. Thanks.

Experience

38 years as research engineer at NASA

Publications
AIAA, NASA

Education/Credentials
B.S. and M.S. Aeronautical Engineering - U. of Washington, Graduate work Standford U.

Awards and Honors
AIAA Associate Fellow (American Institute of Aeronautics and Astronautics)

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