A threshold marking helps identify the beginning of the runway that is available for landing. Runway threshold markings come in two configurations. They either consist of eight longitudinal stripes of uniform dimensions disposed symmetrically about the runway centerline or the number of stripes is related to the runway width as indicated in the table below.
Runway Width | Number of Stripes |
---|---|
60 feet (18 m) | 4 |
75 feet (23 m) | 6 |
100 feet (30 m) | 8 |
150 feet (45 m) | 12 |
200 feet (60) | 16 |
On some occasions, natural and human-made obstacles penetrate the obstacle limitation surface of the approach paths to runways. To ensure that a safe clearance from these obstacles is maintained, it is sometimes necessary to displace the threshold upwind from the adjacent runway end where the approach slope cannot be raised. The portion of runway behind a displaced threshold is available for takeoffs in either direction and landings from the opposite direction. A ten feet wide white threshold bar is located across the width of the runway at the displaced threshold. White arrows are located along the centerline in the area between the beginning of the runway and displaced threshold. In the case of a temporary displacement white arrow heads are located across the width of the runway just prior to the threshold bar, as shown below.
On some occasions, natural and human-made obstacles penetrate the obstacle limitation surface of the approach paths to runways. To ensure that a safe clearance from these obstacles is maintained, it is sometimes necessary to displace the threshold upwind from the adjacent runway end where the approach slope cannot be raised. The portion of runway behind a displaced threshold is available for takeoffs in either direction and landings from the opposite direction. A ten feet wide white threshold bar is located across the width of the runway at the displaced threshold. White arrows are located along the centerline in the area between the beginning of the runway and displaced threshold. In the case of a temporary displacement white arrow heads are located across the width of the runway just prior to the threshold bar, as shown below.
Permanent Displaced Threshold Marking
Temporary Displaced Threshold Marking
The touchdown zone is the first 3,000 feet of the runway or the first third of the runway, whichever is less, measured from the threshold in the direction of landing. The touchdown zone markings identify the touchdown zone for landing operations and are coded to provide distance information in 500 feet (150m) increments. These markings consist of groups of one, two, and three rectangular bars symmetrically arranged in pairs about the runway centerline, as shown below.
Declared Landing Distance Available | Location of Aiming Point Marking Distance From Threshold |
---|---|
less than 800 m | 150 m |
800 m up to but not including 1,200 m | 250 m |
1,200 m up to but not including 2,400 m | 300 m |
2,400 m or more | 400 m |
Although they may appear similar, stopways can support the full weight of an aircraft and are designated for use during a rejected takeoff, while blast pads are not designed to support aircraft weight.