A displaced threshold or DTHR is a

runway According to the International Civil Aviation Organization (ICAO), a runway is a "defined rectangular area on a land aerodrome prepared for the landing and takeoff of aircraft". Runways may be a man-made surface (often asphalt concrete, as ...

threshold located at a point other than the physical beginning or end of the runway. The portion of the runway behind a displaced threshold may be used for

takeoff Takeoff is the phase of flight in which an aerospace vehicle leaves the ground and becomes airborne. For aircraft traveling vertically, this is known as liftoff. For aircraft that take off horizontally, this usually involves starting with a t ...

in either direction and

landing Landing is the last part of a flight, where a flying animal, aircraft, or spacecraft returns to the ground. When the flying object returns to water, the process is called alighting, although it is commonly called "landing", "touchdown" or ...

s from the opposite direction. After landing at the other end, the landing

aircraft An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines ...

may use the area behind the displaced threshold for roll out.Aircraft Information Manual 2013, Chapter 2-3-3 h (2) Section 3. Airport Marking Aids and Signs

/ref> Most often, the offset threshold is in place to give arriving aircraft clearance over an obstruction, while still allowing departing aircraft the maximum amount of runway available. A displaced threshold may also be introduced as a

noise mitigation Noise control or noise mitigation is a set of strategies to reduce noise pollution or to reduce the impact of that noise, whether outdoors or indoors. Overview The main areas of noise mitigation or abatement are: transportation noise control, ...

measure for the communities overflown on approach, or if a beginning section of the runway is no longer able to sustain the continuous impact from landing aircraft. Aircraft are expected to land beyond the displaced threshold. Departing aircraft are permitted to use the section of the runway behind a displaced threshold for takeoffs or landing rollouts from the opposite direction even if the reason for the displacement is lowered pavement resistance, because those aircraft are not impacting the runway with the force of a landing aircraft. A portion of the runway behind a displaced threshold has three markings: * White arrows along the center line of the runway * White arrow heads across the width of the runway just prior to the displaced threshold bar * A wide white threshold bar across the width of the runway at the displaced threshold Runway 29 at

Indira Gandhi International Airport Indira Gandhi International Airport is the primary international airport serving Delhi, the capital of India, and the National Capital Region (NCR). The airport, spread over an area of , is situated in Palam, Delhi, southwest of the New De ...

, in

Delhi Delhi, officially the National Capital Territory (NCT) of Delhi, is a city and a union territory of India containing New Delhi, the capital of India. Straddling the Yamuna river, primarily its western or right bank, Delhi shares borders w ...

, India, has a displaced threshold of from the physical beginning of the pavement.GPS Visualizer : aerial view of the runway with a ruler
(50 meters) This produces a 1.5 km portion of runway that cannot be used for landing in this direction. This, in turn decreases the available landing length on runway 29L to 2,970 m (9,744 ft). The purpose of this large threshold displacement is to reduce noise generated by landing aircraft over nearby localities. Runway 22R at

John F. Kennedy International Airport John F. Kennedy International Airport (colloquially referred to as JFK Airport, Kennedy Airport, New York-JFK, or simply JFK) is the main international airport serving New York City. The airport is the busiest of the seven airports in the Avia ...

has a displaced threshold due to

noise abatement Noise control or noise mitigation is a set of strategies to reduce noise pollution or to reduce the impact of that noise, whether outdoors or indoors. Overview The main areas of noise mitigation or abatement are: transportation noise control, ...

. This shortens the landing distance available to just for the runway.

References

{{Aviation-stub Airport infrastructure