Pilot/Controller Glossary

FLIGHT LEVEL-

This reproduces published FAA reference text for study. It does not replace the current official FAA publication or regulation.

A level of constant atmospheric pressure related to a reference datum of 29.92 inches of mercury. Each is stated in three digits that represent hundreds of feet. For example, flight level (FL) 250 represents a barometric altimeter indication of 25,000 feet; FL 255, an indication of 25,500 feet.

Retrieved from ecfr.gov on July 18, 2026.