What is the main function of the displaced threshold?

The main function of the displaced threshold is to indicate the beginning of usable runway length. A displaced threshold is marked on a runway when the departure or landing area of the runway is relocated to allow for obstacles, such as terrain or structures, at the start of the runway. This alteration ensures that the actual takeoff and landing can occur further down the runway, while still allowing for safe operations.

For pilots and air traffic controllers, the displaced threshold marks the point where the runway becomes usable for landing and takeoff. It helps inform them of the effective available runway length, which is crucial for ensuring that aircraft can safely take off and land without encountering obstacles. Thus, understanding the function of the displaced threshold contributes to maintaining safety standards and operational efficiency at an airport.