What marks the beginning of the landing portion of a runway?

The beginning of the landing portion of a runway is marked by a displaced threshold. A displaced threshold is located at a point on the runway where landing operations can take place, but takeoff operations may not be allowed. This configuration is used to provide additional safety by creating a buffer area for landing aircraft, particularly when the runway has obstacles at the beginning that would interfere with a safe takeoff.

Displaced thresholds are indicated by specific markings that are distinct from the regular runway markings, including arrows pointing towards the landing area and a solid white line that delineates the start of the landing zone. This marking helps pilots identify the appropriate point on the runway to initiate landing procedures safely. In contrast, red light signs, blue arrows, and solid white lines have specific meanings or uses that do not directly signal the start of the landing portion of the runway.