Definition
A specific flight level representing an indicated altitude of 29,000 feet when the altimeter is set to the standard pressure of 29.92 inches of mercury (1013.2 hPa). FL 290 marks the lower boundary of the airspace where Reduced Vertical Separation Minimum (RVSM) procedures are typically applied between FL 290 and FL 410.
Plain English
A cruising height read on the altimeter as 29,000 feet when the altimeter is set to the standard pressure setting. It is the height at which special tighter vertical spacing rules begin for high-altitude traffic.
Context Anchor
You will see FL 290 in high-altitude instrument routing, clearances, charts, and airway descriptions.
Derivation
Flight levels are written without the trailing two zeros, so 'FL 290' means 29,000 feet. The 'flight level' concept exists because above a certain altitude, all aircraft set the same standard pressure (29.92 inHg) on their altimeters rather than the local pressure, so they share a common reference for vertical separation.
Why Pilots Care
Flight levels such as FL 290 provide a standardized altitude reference that ensures safe vertical separation between aircraft.
Analogy
Think of flight levels like everyone measuring from the same shared ruler. The ruler may not show exact height above the ground, but it keeps all aircraft using the same vertical reference.
Intuition Check
FL 290 does not simply mean “29,000 feet above the ground.” It means the 29,000-foot level based on the standard pressure setting.
Example Sentence 1
We were cleared to climb and maintain FL 290 for the transatlantic crossing.
Example Sentence 2
At FL 290 the crew set the altimeters to 29.92 and began the cruise segment of the instrument flight.