What does FL stand for in aviation terminology?

In aviation terminology, FL stands for Flight Level. This term is used to describe an aircraft's altitude expressed in terms of hundreds of feet, measured from a standard altimeter setting of 1013.25 hPa (hectopascals) or 29.92 inHg (inches of mercury). Flight levels are indicated in feet, with the prefix "FL" followed by the altitude number, such as FL350 for 35,000 feet.

Using flight levels is crucial for maintaining safe vertical separation between aircraft in crowded airspace, especially at cruising altitudes. Pilots and air traffic controllers rely on flight levels as a standardized method to ensure that all aircraft are clearly understood in terms of their altitude, regardless of local atmospheric pressure variations. This standardization allows for more efficient communication between pilots and air traffic control, reducing the risk of altitude-related incidents.

Other options, such as "Final Landing," "Fleet Level," and "Fixed Level," do not align with established aviation terminology or altitude reporting methods. They may refer to concepts recognized in specific contexts, but they do not appropriately define the term that FL represents in aviation.