A standard reference for altitude measurement in aviation. Altitudes expressed as MSL indicate the aircraft’s height above the average sea level, not its actual height above the ground. This allows all aircraft to use a common reference point, ensuring consistent altitude separation regardless of terrain elevation.
Key characteristics:
- Standardization: Using MSL ensures that altitude reports are universally understood by pilots and controllers.
- Charts and navigation: Terrain elevations, obstacle heights, and airspace structures are all depicted in MSL on aviation charts.
- Contrast with AGL: Unlike AGL (Above Ground Level), which measures the aircraft’s true height over the terrain beneath it, MSL is a constant global reference.
- Altimeters: Aircraft altimeters set to the local pressure setting (QNH) display altitude in MSL.
Application in DCS World
- DCS aircraft altimeters display altitude in MSL when properly calibrated, matching real-world procedures. Charts and mission editor elevations are also given in MSL.
- DCS ATC and AI JTACs sometimes use AGL when giving target elevation, which can cause confusion. Unlike real-world ATC, DCS does not always clarify MSL vs AGL explicitly.
Cadets should practice interpreting altimeter settings, chart elevations, and mission brief data in MSL. They should also learn to mentally distinguish MSL from AGL, especially in mountainous terrain or during CAS/JTAC briefs.