Threshold Crossing Height (TCH)

Threshold Crossing Height (TCH) is the height of the point in the approach path (on the glidepath or MDA) at which the aircraft’s reference point (typically the main wheel contact point for the landing gear) crosses the runway threshold. TCH is used to ensure the aircraft clears the threshold at a safe height.

TCH and Obstacle Clearance

The TCH is published on instrument approach charts and is typically between 15 and 60 ft. A higher TCH results in a longer float and touchdown further down the runway. A very low TCH means the aircraft crosses the threshold close to the pavement — requiring precision approach execution.

Related Terms

See also: Threshold, Glide Slope, ILS.