What is the purpose of an Altimeter setting during IFR flights?

The purpose of an altimeter setting during IFR (Instrument Flight Rules) flights is to ensure correct altitude and avoid terrain. The altimeter measures the aircraft's altitude based on local atmospheric pressure, which can vary significantly with changes in weather conditions. By setting the altimeter to the correct pressure setting before takeoff and during your flight, you establish a reference point that allows you to maintain altitude and avoid possible obstacles or terrain hazards.

When flying under IFR, pilots rely on accurate altitude information to safely navigate and avoid controlled airspace and other aircraft. The altimeter setting plays a crucial role in ensuring that the pilot has a clear understanding of their altitude relative to sea level and surrounding terrain, ultimately contributing to flight safety. This function is critical in preventing controlled flight into terrain (CFIT) incidents, especially in poor visibility conditions.