What is the purpose of the Altimeter setting in an aircraft?

The purpose of the altimeter setting in an aircraft is to ensure that the aircraft maintains the correct altitude above sea level. An altimeter is a vital instrument that measures the atmospheric pressure outside the aircraft, which correlates to altitude. By setting the altimeter correctly, pilots can reference their altitude accurately based on local atmospheric conditions.

In aviation, altitude is crucial for separation from terrain and other aircraft, especially during en route flight and in busy airspace. The altimeter setting is adjusted according to the local barometric pressure, which can change with weather conditions, ensuring that pilots have an accurate indication of their altitude relative to sea level. This helps maintain safe flying heights and avoid obstacles or other aircraft, which is essential for flight safety.

While effective communication with air traffic control is vital, the altimeter does not play a direct role in that process. Similarly, calculating flight duration and determining fuel efficiency are influenced by other factors such as airspeed and fuel flow—thus, they are unrelated to the primary function of the altimeter.