Displaced threshold
Displaced threshold: landing threshold moved down the runway, arrows leading to it.
Pavement before the arrows (AGA 3.5):
| Use | Allowed |
|---|---|
| Taxi | Yes |
| Takeoff roll | Yes |
| Rollout (from opposite direction) | Yes |
| Touchdown | No |
Why displaced:
- Obstacle penetrates approach obstacle limitation surface, slope can't be raised: threshold moves for safe clearance (TC Self-Paced Study Program, recency, Answer Key Q6; AGA 3.5).
- Same obstacle can carry a published specified climb gradient and/or visibility minimum for takeoff from that end (AGA 3.5).
Markings:
| Displacement | Marking (TP 1102) |
|---|---|
| Temporary | Four white arrowheads spaced across the approach side, pointing to new threshold |
| Permanent | Two white arrows, one behind the other on old centreline, pointing to new threshold |
- Threshold bar across the displaced portion, arrows leading up to it (AGA 5.4.1).
Relatively short-term displacement (TC AIM AGA 5.4.1):
- Flags, cones, or wing bar lights may replace painted threshold bar.
- NOTAM or voice advisory gives: markers, expected duration, closed length, remaining usable runway.
Trap: pavement before the arrows: taxi and takeoff yes, touchdown never.
References
- TC AIM AGA 3.5
- TC AIM AGA 5.4.1
- TP 1102
- TC Self-Paced Study Program (recency)