Refer to figures.
When the threshold of a runway is not located at the extremity of the runway, then a displaced threshold exists. The displaced threshold is included in the TORA (Take-off run available) and can be used during the take-off run, but it is not part of the LDA (Landing Distance Available) and can not be used for landing purposes. In order to calculate the LDA, the displaced threshold length should be removed from the TORA length:

• LDA = TORA - displaced threshold length = 2100 m - 100 m = 2000 m

Note: The stopway length is not needed.

ICAO Annex 14 - DEFINITIONS

Displaced threshold. A threshold not located at the extremity of a runway.

Declared distances.

a) Take-off run available (TORA). The length of runway declared available and suitable for the ground run of an aeroplane taking off.
b) Take-off distance available (TODA). The length of the take-off run available plus the length of the clearway, if provided.
c) Accelerate-stop distance available (ASDA). The length of the take-off run available plus the length of the stopway, if provided.
d) Landing distance available (LDA). The length of runway which is declared available and suitable for the ground run of an aeroplane landing.

Stopway. A defined rectangular area on the ground at the end of take-off run available prepared as a suitable area in which an aircraft can be stopped in the case of an abandoned take-off.

ATTACHMENT A. GUIDANCE MATERIAL SUPPLEMENTARY TO ANNEX 14, VOLUME I
3. Calculation of declared distances

3.5 Where a runway has a displaced threshold, then the LDA will be reduced by the distance the threshold is displaced, as shown in Figure A-1 (D). A displaced threshold affects only the LDA for approaches made to that threshold; all declared distances for operations in the reciprocal direction are unaffected.