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Pressure Altitude

Calculate pressure altitude based on ambient pressure

Library

Environment/Atmosphere

Description

The Pressure Altitude block computes the pressure altitude based on ambient pressure. Pressure altitude is the altitude in the 1976 Committee on the Extension of the Standard Atmosphere (COESA) United States with specified ambient pressure.

Pressure altitude is also known as the mean sea level (MSL) altitude.

The Pressure Altitude block icon displays the input and output units selected from the Units list.

Dialog Box

Units

Specifies the input units:

Units

Pstatic

Alt_p

Metric (MKS)

Pascal

Meters

English

Pound force per square inch

Feet

Action for out of range input

Specify if out-of-range input invokes a warning, error, or no action.

Inputs and Outputs

InputDimension TypeDescription

First

 Contains the static pressure.

OutputDimension TypeDescription

First

 Contains the pressure altitude.

Assumptions and Limitations

Below the pressure of 0.3961 Pa (approximately 0.00006 psi) and above the pressure of 101325 Pa (approximately 14.7 psi), altitude values are extrapolated logarithmically.

Air is assumed to be dry and an ideal gas.

Reference

U.S. Standard Atmosphere, 1976, U.S. Government Printing Office, Washington, D.C.

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