What is the primary function of an altimeter?

The primary function of an altimeter is to measure the height of an aircraft above sea level. This is essential for flight safety and navigation, as it provides pilots with crucial information about their altitude during different phases of flight, especially during takeoff and landing, where precise altitude readings are necessary to maintain safe distances from the ground and other aircraft.

Altimeters work by measuring air pressure; as the aircraft ascends or descends, the air pressure changes, allowing the altimeter to provide an accurate reading of the aircraft's elevation relative to sea level. This measurement is vital for adherence to air traffic control instructions and for ensuring the aircraft remains within safe altitude limits, particularly when flying in crowded airspace or during adverse weather conditions.

In contrast, measuring the speed of the aircraft is the role of a different instrument known as the airspeed indicator, while calculating flight routes involves navigation systems and flight plans. Tracking fuel consumption is managed by fuel gauges and onboard systems specifically designed for that purpose.