What is the primary purpose of adjusting minimum flight levels based on altimeter settings?

The primary purpose of adjusting minimum flight levels based on altimeter settings is to ensure safety between aircraft. By adjusting flight levels according to the local altimeter settings, air traffic controllers and pilots can maintain appropriate vertical separation, which is crucial in preventing mid-air collisions. The altimeter measures the aircraft's altitude based on air pressure, and variations in pressure can affect altitude readings. Properly calibrating altimeter settings allows for consistent and accurate altitude assignments, ensuring that aircraft are at safe distances from one another in the vertical airspace. This is essential for maintaining safety in busy airspaces and during various phases of flight, particularly during ascent and descent.