What does FL represent in aviation?

In aviation, "FL" stands for "Flight Level." This term is used to describe the altitude of an aircraft in nautical miles based on standard atmospheric pressure. Flight levels are expressed in hundreds of feet. For example, FL350 indicates that the aircraft is at 35,000 feet above sea level, and this standardization helps ensure safe spacing and separation between aircraft operating at different altitudes.

Using "Flight Level" allows pilots, air traffic controllers, and meteorologists to communicate consistently regarding altitude, especially when aircraft are flying above 18,000 feet, where altimeters are commonly set to 29.92 inches of Mercury (Hg). This aids in maintaining safe navigation and effective management of the airspace.

While the other options suggest various concepts relating to flight, they do not accurately define the term "FL" within the context of aviation terminology.