Displaced Threshold
A displaced threshold is a runway threshold that is located at a point other than the physical beginning of the runway pavement. The area before the displaced threshold may be used for take-off or landing roll-out (if approaching from the opposite end) but may not be used for landing. The displaced threshold is marked by white arrows on the pavement leading to the threshold bar.
Why Thresholds Are Displaced
- Obstacle clearance: structures or terrain before the runway require a higher approach angle, so the threshold is moved to provide the required approach slope clearance
- Pavement condition: the beginning of the runway may not be of landing-quality surface
- Noise abatement: moving the threshold further from a residential area reduces noise exposure
Rules for Displaced Threshold Operations
- Landings must touch down at or beyond the displaced threshold
- The paved area before the displaced threshold may be used for take-off roll only
- When approaching from the other direction, the area before the displaced threshold is usable for landing roll-out