Airline Transport Pilot Written Knowledge Practice Test 2026 - Free Practice Questions and Study Guide

The purpose of the altimeter setting in aviation is to ensure that an aircraft maintains the correct altitude above sea level. An altimeter measures the atmospheric pressure and translates it into an altitude reading, allowing pilots to know their elevation in relation to sea level. This is critical for safe navigation, especially when flying at high altitudes or when approaching airports, where maintaining a specific altitude is essential for avoiding obstacles and ensuring separation from other aircraft.

Setting the altimeter correctly ensures that all aircraft within a specific airspace are using a common reference for altitude, which enhances safety and situational awareness for pilots and air traffic control. The altimeter is typically set to the current barometric pressure, which can change depending on weather conditions, and pilots must adjust it regularly to maintain accurate readings.