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A runway has a total length of 1150 m, including a stopway of 30 m and a 25 m displaced threshold. What is the landing distance available?

  • A

    1125 m

  • B

    1150 m

  • C

    1180 m

  • D

    1095 m

Refer to figure.
The landing distance available (LDA) is the area of the runway prepared for an aircraft to overfly the runway at the screen height (50 ft), touchdown and decelerate to a stop. The LDA begins at the threshold where the aircraft should be at 50 ft.

A displaced threshold is one where the landing point of the runway has been displaced forward. This will shorten the landing distance available (LDA) for a given runway length, however the area before the displaced threshold can still be used for the takeoff run. The threshold is often displaced to ensure obstacle/terrain clearance for landing aircraft. 

A stopway is an area specially prepared to support an aircraft during a rejected takeoff. It may be an engineered surface that is only to be used in an emergency, and so a stopway is not part of the LDA. 

Given the total runway length including stopway and displaced threshold, we must subtract both of those distances to find the LDA. 

In this question:
LDA = 1150 - 30 - 25 = 1095 m

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