What does absolute altitude indicate?

Absolute altitude refers to the height of an aircraft above the terrain directly beneath it. It is a critical measurement for pilots, especially when flying at low altitudes where terrain clearance is a concern. This altitude is not concerned with reference points like mean sea level or standard datum planes, but instead focuses on how high the aircraft is above the ground level itself.

In aviation, knowing the absolute altitude is particularly important for terrain avoidance and operating safely in mountainous regions. It helps pilots maintain safe distances from the ground and other obstacles, ensuring flights can be conducted safely.