Sunday, November 18, 2007


The altimeter measures the height of the airplane above a given pressure level. Since it is the only instrument that gives altitude information, the altimeter is one of the most vital instruments in the airplane. To use the altimeter effectively, its operation and how atmospheric pressure and temperature affect it must be thoroughly understood. A stack of sealed aneroid wafers comprises the main component of the altimeter.

These wafers expand and contract with changes in atmospheric pressure from the static source. The mechanical linkage translates these changes into pointer movements on the indicator.

1 comment:

    Altimeter tests are performed in accordance with FAR Part 43, Appendix E. If the altimeter test is to be performed with the instrument installed in the airplane, the following guidelines should be observed:

    a. The static leak test should be conducted first to assure that there are no static system leaks to influence altimeter indications.
    b. Permit the altimeter to stabilize after a flight before performing the test.
    c. Use portable test equipment or barometric test equipment as described in paragraph 7, Altimeter Test Equipment.
    d. When vibration is applied to the instrument, assure that it is not of a magnitude which will mask a sticky altimeter.