What is the purpose of the altimeter during IFR flight?

The purpose of the altimeter during IFR flight is to measure the aircraft's altitude. This instrument is crucial for maintaining the correct flight level and ensuring safe vertical separation from other aircraft. An altimeter provides pilots with altitude information by measuring the atmospheric pressure surrounding the aircraft. As the aircraft climbs or descends, the pressure changes, and the altimeter adjusts to reflect the current altitude.

This function is particularly important in Instrument Flight Rules (IFR) because pilots often rely on instruments for navigation and situational awareness, especially when visibility is poor or non-existent. Accurate altitude readings help prevent controlled flight into terrain and ensure compliance with altitude restrictions set in air traffic control clearances. The ability to accurately measure altitude is fundamental for safe flight operations in controlled airspace.