Flight level (FL)

Flight Level (FL)

Flight Level (FL) is a standardized measure of altitude used by airplanes flying above 18,000 feet, based on the international standard atmosphere at standard air pressure, 1013.25 hPa (29.92 inHg). FL is expressed in hundreds of feet, for example, FL370 represents an altitude of 37,000 feet. The use of Flight Levels allows for pilots to maintain safe vertical separation while in flight. This measure of altitude is obtained through the altimeter set at 29.92 “Hg.