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FL 600 — Aviation Definition | Keynomen Aviation

Words for: Airspace

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FL 600

FL is the abbreviation for Flight Level.

Plain English Meaning

A way of stating altitude that means about 60,000 feet above sea level, measured against a fixed standard pressure setting rather than the local pressure of the day.

Full Definition

Flight Level 600, equivalent to a pressure altitude of approximately 60,000 feet when the altimeter is set to the standard pressure of 29.92 inches of mercury. It marks the upper boundary of Class A airspace in the United States.

Context Anchor

Seen in high-altitude airspace discussions, instrument flying material, charts, and air traffic control clearances.

FL 600

Derivation

Flight Level' is the term used above 18,000 feet in the U.S. where all aircraft set their altimeters to the same standard pressure (29.92 inHg) so that everyone is measuring altitude from the same reference. The number after 'FL' is the altitude in hundreds of feet, so FL 600 means 60,000 feet.

Why Pilots Care

Correct flight level assignment ensures vertical separation from other traffic in upper airspace.

Intuition Check

FL 600 does not mean 600 feet. In flight levels, the number is counted in hundreds of feet, so FL 600 means 60,000 feet on the standard pressure setting.

Example Sentence 1

Class A airspace in the United States extends from 18,000 feet MSL up to and including FL 600.

Example Sentence 2

Charts show the transition to FL 600 for operations above the troposphere.