What is the function of the altimeter in aviation?

The altimeter's primary function in aviation is to measure the aircraft's altitude by detecting changes in air pressure. The altimeter operates on the principle that atmospheric pressure decreases with an increase in altitude. As the aircraft ascends, the pressure decreases and the altimeter reflects this change by indicating a higher altitude. This information is vital for pilots to maintain safe flying levels, ensure separation from terrain and other aircraft, and comply with air traffic control requirements.

While wing loading is an important concept in aviation, it pertains to the distribution of the aircraft’s weight relative to its wing area, which the altimeter does not measure. Similarly, the altimeter does not provide direct information about the distance traveled; that would be the function of a separate instrument like a GPS or odometer. The determination of outside air temperature is typically made by a thermometer or temperature probe, not by the altimeter, which solely provides altitude data based on pressure changes.