Instrumentsaltimetry
Flight Level
A flight level is an altitude expressed in hundreds of feet, indicated on an altimeter set to the standard atmospheric pressure datum of 1013.2 hPa. Flight levels are used above the transition altitude to ensure all aircraft use a uniform pressure reference for vertical separation.
Key Points
- •Read from an altimeter calibrated to 1013.2 hPa, not the local QNH.
- •Expressed as 'FL' followed by three digits — for example, 11,000 ft is FL110.
- •Ensures standardised vertical separation in the upper airspace.
Exam Relevance
Fundamental for altimetry questions, cruising level selection, and understanding when to switch from local QNH to the standard pressure setting.
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