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This glossary is written for virtual airline and flight simulation use within Virtual Air Canada Airline. It is not intended as a real-world aviation reference.
Above Ground Level is an altitude measurement expressed as height above the terrain directly below the aircraft. This differs from altitude referenced to mean sea level (MSL), which is what a standard altimeter displays when set to QNH. AGL readings change as terrain elevation changes, even if the aircraft maintains a constant MSL altitude. Radio altimeters (radar altimeters) provide direct AGL measurements by bouncing radio signals off the ground below. These readings are critical during approach and landing, particularly for precision approaches where decision heights are expressed in feet AGL. Radio altimeter callouts (e.g., “100 feet”, “50 feet”, “30 feet”) guide the pilot during the final moments before touchdown.

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In Virtual Airline Operations

AGL awareness is important during approach and landing phases in the simulator. Most study-level aircraft model radio altimeter callouts, and Pegasus ACARS uses AGL-related data when scoring your landing. Understanding the difference between AGL and MSL helps with proper approach briefing and execution.
  • AFE - Above Field Elevation
  • FL - Flight Level
  • DA/DH - Decision Altitude/Decision Height
  • MSA - Minimum Sector Altitude