What is the definition of aircraft altitude above ground level, abbreviated as AGL?

The definition of aircraft altitude above ground level, abbreviated as AGL, refers specifically to the height of an aircraft as it relates to the surface of the terrain directly beneath it. This measurement is crucial in aviation because it provides a sense of the aircraft's clearance above potential obstacles and the ground itself, which is vital for safety and navigation.

Unlike altitude above sea level, which takes into account the average level of the ocean and can vary based on geographic location, AGL is concerned solely with the immediate elevation of the ground underneath the aircraft. This distinction is essential for pilots when considering terrain and obstacles such as buildings, towers, and trees, particularly in low-altitude operations like aerial surveys, film production, or agricultural applications.

Understanding AGL is significant for drone operators and pilots alike, as it helps ensure compliance with regulations regarding minimum safe altitudes and aids in the avoidance of accidents, providing a more accurate assessment of operational conditions.