Threshold

The threshold is the beginning of the portion of a runway that is available and suitable for landing. It is marked by transverse white stripes across the runway width. Aircraft must cross the threshold at an appropriate height and touch down after the threshold.

Displaced Threshold

When the threshold is displaced from the physical beginning of the runway pavement, white arrows along the pavement lead to the threshold bar. The paved area before the displaced threshold may be used for take-off roll or roll-out from the opposite direction but may NOT be used for landing.

Threshold Crossing Height

The approach profile is designed so the aircraft crosses the threshold at a specific height — Threshold Crossing Height (TCH), typically 15–60 ft above the threshold for various approach types. The PAPI and ILS glidepath are designed to achieve this crossing height.

Related Terms

See also: Displaced Threshold, Threshold Crossing Height, Runway.