Following are the standard declared distances by ICAO for performance calculations.
Clearway, Stopway, TORA, TODA, ASDA & LDA
Clearway is the area beyond the runway not less than 152m wide centrally located about the extended centerline of the runway and under the control of airport authorities. Clearway is expressed as a plane extending from the end of runway with up slop not exceeding 1.25% above which no object or terrain protrudes with exception of threshold lights.
Stopway is the area at the end of take-off runway no less wide than the runway and centered upon extended centerline of runway and able to support the aeroplane during an aborted take-off without causing structural damage to the aeroplane.
TORA (Take off Run Available)
TORA is defined as length of runway suitable for normal operations. It need not always equal to LDA (landing distance available). TORA doesn’t include Stopway or Clearway.
TODA (Take off Distance Available)
TODA is the length of runway plus any clearway if available. In case no clearway exists, TODA is same as TORA. TODA includes ground as well as air segments.
ASDA (Accelerate-Stop Distance Available)
ASDA is used for calculation of V1. It is defined as sum of LDA/TORA (as applicable) and Stopway. In case take off is aborted the aircraft can be brought to a stop either on the runway or on Stopway.
ASDA must not be used as TORA.
LDA (Landing Distance Available)
LDA is the runway length declared available and suitable for landing an airplane.
Information on Clearway, Stopway, TORA, TODA, ASDA & LDA for different runways can be obtained from Aerodrome Information Publications, Jepessen Charts and RTOW charts.
Also Read – Engine Out SID and Missed Approach Procedure