Altimeter[PDF]

Mechanism

The altimeter displays the altitude of the airplane above mean sea level (MSL) when properly adjusted to the current pressure setting. The value is expressed in feet (ft); it can be meters (m) in some aircraft.

Aircraft altimeter.JPG

In aircraft, an aneroid barometer measures the atmospheric pressure from a static port outside the aircraft.
Air pressure decreases with an increase of altitude—approximately 100 hectopascals per 800 meters or one inch of mercury per 1000 feet near sea level.

Aspect

The analogic altimeter has 2 needles:

  • The longest one for the hundreds of feet
  • The shortest one for the thousands of feet

Example of altimeter reading.png

The direct value of the altimeter can be displayed directly in some instruments with only the long needle for hundreds of feet.
Mid-age altimeter.png

Use

Note that the altimeter shall be calibrated with the pressure value in hPa or inHg using the rotating knob on the bottom left or bottom right of the instrument.
The pressure chosen can be local airfield pressure QNH or standard QNH 1013 hPa / 29,92 inHg dependent on your altitude and country regulation.

Refer to the altimeter setting methodology page for more information


See also

Reference

  • None

Author

  • VID 150259 - Creation
  • VID 200696 - Update

DATE OF SUBMISSION

  • 02:14, 14 May 2021

COPYRIGHT

  • This documentation is copyrighted as part of the intellectual property of the International Virtual Aviation Organisation.

DISCLAIMER

  • The content of this documentation is intended for aviation simulation only and must not be used for real aviation operations.