AGL

AGL (Above Ground Level) refers to altitude measured from the ground directly below the aircraft. This contrasts with MSL (Mean Sea Level), which measures altitude from sea level regardless of terrain elevation.

AGL is commonly used for:

• Traffic pattern altitudes
• Obstacle heights on approach charts
• Minimum safe altitudes over terrain
• Regulatory altitude limits (e.g., 500 ft AGL minimum over non-congested areas)

Radar altimeters measure AGL directly, while barometric altimeters display MSL altitude.