How Does An Altimeter Work

Learn how the altimeter measures the height of an aircraft above a fixed level by sensing the ambient air pressure. Find out the difference between actual, indicated, absolute, and density altitude, and how to set the altimeter to the current local pressure. Learn how altimeters measure height above different pressure levels using sealed wafers or electronic sensors.

Find out how to adjust your altimeter setting for nonstandard air pressure and how to read a 3-hand or glass-panel altimeter. Altitude can be determined by the measurement of atmospheric pressure. The greater the altitude, the lower the pressure.

When a barometer is supplied with a nonlinear calibration so as to indicate altitude, the instrument is a type of altimeter called a pressure altimeter or barometric altimeter. An easy-to-understand introduction to how airplanes measure altitude using pressure and radio altimeters. The pressure altimeter operates on the principle that average atmospheric pressure decreases linearly with altitude.

A typical pressure altimeter is illustrated in the figure. Altimeters work by sensing changes in air pressure, which decreases as altitude increases. By measuring the ambient air pressure, the altimeter can determine how high you are above sea level.

Altimeters measure changes in atmospheric pressure as the plane climbs or descends. It has no reference to the ground or even sea level. When correctly set, the altimeter reads height above mean sea level, known as MSL.

The altimeters found in aircraft are barometric sensitive altimeters. To understand how an altimeter works, lets start with the basics. An altimeter is essentially a barometric sensor that measures air pressure to determine altitude.

As we ascend, air pressure decreases, and the altimeter responds by indicating an increase in altitude. The most common altimeter works on a straightforward principle measures atmospheric pressure. Since air pressure decreases predictably with increasing altitude, the instrument can translate that change into a direct elevation reading.

This altimeterthe instrument that displays "Height"shows the altitude of a helicopter that is hovering below sea level near the Dead Sea. Altimeters measure altitude.