In the handoff phrase, what does 'FL' stand for?

The term 'FL' in the context of air traffic control and handoffs refers to 'Flight Level'. This designation is used to indicate the altitude of an aircraft in reference to standard atmospheric pressure, which is predefined as 1013.25 hPa (hectopascals) or 29.92 inHg. Flight levels provide a standardized way for pilots and air traffic controllers to communicate altitude, ensuring clarity in navigation and separation between aircraft. For example, if an aircraft is flying at an altitude of 10,000 feet with a standard pressure setting, it would be referred to as FL100.

Understanding the use of 'Flight Level' is crucial for pilots and ATC personnel alike, as it helps maintain safe vertical separation between different aircraft during flight, particularly in congested airspaces.