Runway Declared Distances are specific lengths of runway which are available for aircraft operations when taking off or landing. They are published to guide Pilots in understanding their allowable take-off and landing weights and speeds. The declared distances for a runway comprise the Take-Off Run Available (TORA), Take-Off Distance Available (TODA), Accelerate-Stop Distance Available (ASDA), and Landing Distance Available (LDA).
To understand the definition of each declared distance, a look at the definitions of Clearway, Stopway, and Displaced Threshold, which are related terms, is necessary.
- Clearway (CWY) – A defined rectangular area on the ground or water under the control of the appropriate authority selected or prepared as a suitable area over which an aeroplane may make a portion of its initial climb to a specified height.
- Stopway (SWY) – 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.
- Displaced Threshold – A threshold not located at the extremity of a runway.
The definitions of each declared distance as defined by ICAO, are as follows:
- TORA (Take-Off Run Available) – The length of runway declared available and suitable for the ground run of an aeroplane taking off.
- TODA (Take-Off Distance Available) – The length of the Take-Off Run Available (TORA) plus length of the Clearway (CWY), if provided.
- ASDA (Accelerate-Stop Distance Available) – The length of Take-Off Run Available (TORA) plus the length of the Stopway (SWY), if provided.
- LDA (Landing Distance Available) – The length of the runway declared available and suitable for the ground run of an aeroplane landing.
LDA reduces where there is a displaced threshold.
REFERENCES
ICAO Annex 14
