The Altimeter - Aircraft Cockpit Instrument

Aircraft Altimeters are one of the six basic cockpit instruments that a pilot references during flight. Simple and basic, the altimeter’s purpose is to inform the pilot what altitude the aircraft is flying at. While newer altimeters are computerized and use high-tech sensors to detect the altitude, traditional altimeters measure the altitude by analyzing atmospheric pressure and comparing it to a preset value that the pilot or engineer has previously inputted.

Inside the instrument, Aircraft altimeters typically have three aneroid wafers that can expand, and contract sealed within a casing. There aneroid wafers are calibrated at 29.92” Hg, sea level. And while there are many variations in appearance, the most common is the 3-Point Altimeter with a background that looks like a clock with numbers from 0 to 9 and three needles. The three needles show different altitude values. The short, wider needle shows altitude in 10,000 ft increments, the slightly longer one shows the 1,000 ft increments, and the longest needle shows the 100 ft increments. The three-needle system makes it easy for pilots to immediately know the altitude at first glance with just a bit of training. The display is the most integral part of the altimeter. Most altimeters today use the Kollsman window. This is an adjustable dial that makes it possible for the pilot to input the local pressure values for the flight. These inputs can be much more accurate depending where you are in the world.

Although the altimeter is an amazing flight instrument part, it does have its weaknesses. Disturbed airflow in static ports can lead to erroneous readings. Overtime, the expansion and contraction of the aneroid wafers can lead to metal fatigue and therefore also cause erroneous readings. The weather, pilot mistakes/misuse, and normal wear and tear can all cause incorrect readings. And yet, altimeters are still one of the most vital components in a pilot’s repertoire.

But, no matter what, an instrument is only good if it works. For all your altimeter parts and replacements, see us at NSN Components. We’re be able to provide you the best altimeters on the market fast and for a very competitive price. Our dedicated staff will be able to get you everything you need so that you can be ready to fly again. Just call us at +1-714-705-4780 or email us at sales@nsncomponents.com to get started on a quote. 

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1. alex marsh
2. Posted on January 17, 2019
3. avionics

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