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MSL (Mean Sea Level)
A measurement of altitude expressed in feet above the average level of the ocean surface. MSL altitude is used for en route navigation, airspace boundaries, and instrument approach procedures. Altimeters display MSL altitude when set to the local altimeter setting.
Related Terms
- Multi-Engine RatingAn add-on rating to a pilot certificate that authorizes the pilot to fly aircraft with more than one engine. Training focuses on engine-out procedures, Vmc demonstrations, asymmetric thrust management, and multi-engine systems.
- Night CurrencyThe recent flight experience required to carry passengers at night. Under 14 CFR 61.57(b), a pilot needs three takeoffs and three landings to a full stop within the preceding 90 days, accomplished during the period from one hour after sunset to one hour before sunrise.
- NOTAM (Notice to Air Missions)A notice containing information concerning the establishment, condition, or change in any aeronautical facility, service, procedure, or hazard. Pilots are required to check NOTAMs during preflight planning.
- Outlook BriefingA Flight Service weather briefing used for early planning when departure is six hours or more away. An outlook briefing highlights whether a weather system or broad hazard may affect the flight, but it is not a substitute for a standard or abbreviated briefing closer to departure.