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Airports
Published in Suzanne K. Kearns, Fundamentals of International Aviation, 2021
As the surface height of Earth is variable—from low points at the ocean level to high points on mountain peaks—airport position must also be given vertically. Airport elevation is expressed in feet above mean sea level (MSL). Aircraft altimeter readings, which inform pilots of their altitude, also reference MSL elevations. For example, when a pilot is at an airport with an elevation of 800 feet MSL, the altimeter will read 800 feet while the aircraft is still on the ground. After takeoff, the pilot will have to subtract 800 from the altimeter reading to calculate height above ground level (AGL).
Airports
Published in Suzanne K. Kearns, Fundamentals of International Aviation, 2018
As the surface height of the earThis variable – from low points at ocean level to high points on mountain peaks – airport position must also be expressed vertically. Airport elevation is expressed in feet above mean sea level (MSL). Aircraft altimeter readings, which inform the pilot of altitude, also reference MSL elevations. For example, when a pilot is at an airport with an elevation of 800 feet MSL, the altimeter will read 800 feet while the aircraft is still on the ground. After take-off, the pilot will have to subtract 800 from the altimeter reading to calculate height above ground level.
Retarded state-multiplicative stochastic systems - Robust H ∞ and H 2 vertex-dependent filtering
Published in International Journal of Control, 2022
In order to demonstrate the application of the our theory to practical control engineering, we consider the problem of altitude estimation with measurements from a RADAR altimeter and a baro altimeter (Gershon et al., 2005). We bring a short description of the problem at hand for convenience. The barometric altitude measurement is based on a static pressure measurement. As a result of various sources of error, (e.g. initial reference error, static pressure measurement bias, or temperature measurement errors) the baro altimeter is corrupted with a bias error (see Chapter 11, Gershon et al., 2005) up to 1000 ft together with a small white noise component. Denoting the true altitude above ground by h, we have the following approximate model for the altitude hold loop which is commanded by the altitude command where is the time constant of the command response, b represents the baro altitude measurement bias and is a standard zero-mean white noise with intensity , that is: The RADAR altimeter measures the height above ground level without bias, however, its output is corrupted by a broad band measurement noise, the intensity of which increases with height due to a lower SNR (signal to noise ratio) effect at higher altitude.