What does Mean Sea Level (MSL) measure?

Mean Sea Level (MSL) is a standardized measurement that represents the average height of the sea's surface over a period of time, typically taken from the average of the high and low tides. It is crucial for aviation and navigation as it provides a consistent reference point for altitude measurements.

Using MSL allows pilots to determine the altitude of their flight relative to the average sea level, rather than the ground elevation, which can vary significantly based on topography. Tracking altitude using MSL helps ensure safe distances above sea level, aiding in obstacle clearance and providing a uniform reference for reporting altitude across different geographic locations.

This concept is essential in aviation as it supports altitude reporting and navigation, particularly in air traffic control and flight operations where precise altitude management is critical for safety.