ASDA is the declared runway plus any stopway available for an aircraft to accelerate to V1 and, if necessary, abort the takeoff and stop safely. It is a critical measure for flight planning and safety compliance.
Declared distances are vital regulatory values set by airport authorities (per ICAO Annex 14 and FAA AC 150/5300-13B) to specify the maximum portions of a runway and associated areas available for takeoff, rejected takeoff, and landing. The four principal declared distances are:
These values are critical for safety, compliance, and precise aircraft performance calculations. They are not always equal to the physical runway length due to factors like stopways, clearways, displaced thresholds, and safety or obstacle protection requirements. Understanding and correctly applying each declared distance is essential for safe and compliant airport and flight operations.
ASDA is the length of runway plus any declared stopway available for an aircraft to accelerate from a standstill to the takeoff decision speed (V1), and, if necessary, abort the takeoff and come to a complete stop. The airport authority determines and publishes this value.
ASDA is always based on thorough safety and regulatory assessments, including runway safety areas (RSA), runway protection zones (RPZ), and obstacle evaluation. Operators and pilots must always use the published ASDA, not the physical runway length, for all takeoff performance calculations.
TORA is the length of runway declared suitable for the aircraft’s ground run during takeoff. It usually matches the physical runway, but may be shorter due to safety area requirements.
Key points:
TODA is the sum of TORA and any declared clearway. The clearway is an obstacle-free area beyond the runway, not required to support aircraft weight or be load-bearing.
Key points:
ASDA is the declared length of runway plus any stopway available for an aircraft to accelerate to the takeoff decision speed and, if necessary, abort the takeoff and stop safely.
Key points:
LDA is the length of runway declared suitable for landing, measured from the (possibly displaced) threshold to the runway end. It does not include stopways or clearways.
Key points:
A stopway is a prepared area at least as wide as the runway, suitable to support an aircraft during an aborted takeoff, but not for normal use. Only included in ASDA; not in TORA, TODA, or LDA.
A clearway is an obstacle-free area beyond the runway end, controlled by the airport, and not required to be load-bearing. Used only in TODA for certified operations.
A displaced threshold is a landing threshold located away from the physical runway start, often due to obstacles or pavement issues. Landings must occur beyond the displaced threshold.
RSA is a graded, cleared area to minimize aircraft damage during overruns or excursions. RPZ is a ground area beyond the runway end for public safety. Both can result in reductions to declared distances if minimum standards are not met.
ASDA may be shorter, equal to, or longer than the physical runway due to:
Important: Always use only the declared ASDA, never assume it equals the physical runway length.
Runway length at which accelerate-go and accelerate-stop distances are equal. ASDA is the limiting factor for balanced field calculations.
Used when ASDA or other declared distances create asymmetric constraints; calculations may favor either accelerate-stop or accelerate-go, as supported by aircraft data and regulations.
Declared distances are published in:
A graded area to minimize aircraft damage during overruns or excursions. If RSA cannot be provided, declared distances may be reduced.
Ground area for safety of people and property beyond the runway; strict land-use controls apply.
A bed of crushable material at the runway end for overrunning aircraft. EMAS may allow shorter declared distances or mitigate for insufficient RSAs, but is not part of declared distances unless published.
A landing threshold set away from the runway start, reducing LDA and possibly affecting other declared distances.
ASDA is a safety-critical, declared runway distance representing the maximum length available for an aircraft to accelerate to V1 and, if necessary, stop safely during a rejected takeoff. It is determined and published by airport authorities and may differ from the physical runway length due to the inclusion of stopways or regulatory constraints. Correct understanding and application of ASDA, along with other declared distances (TORA, TODA, LDA), are essential for safe, compliant, and efficient flight and airport operations. Always consult current, official sources for declared distances, and never use physical dimensions or assumptions for performance calculations.
ASDA, or Accelerate-Stop Distance Available, is the declared length of runway plus any stopway that an aircraft can use to accelerate to takeoff decision speed (V1) and, if necessary, abort the takeoff and stop safely. ASDA is published by airport authorities and is a critical factor in takeoff performance and flight planning.
ASDA may differ from the physical runway length due to the inclusion of stopways or reductions for safety areas or obstacles. It can be shorter, equal to, or longer than the physical runway, depending on declared stopways and regulatory constraints. Only the published ASDA should be used for performance calculations.
Declared distances, including ASDA, are published by airport authorities and can be found in official documents like the FAA Chart Supplement, Jeppesen charts, ICAO AIPs, and other national supplements. On US charts, the 'inverted D' symbol indicates declared distances are available.
ASDA ensures that an aircraft can safely abort takeoff and stop within the available distance, accounting for runway and stopways. It is vital for regulatory compliance and operational safety, as exceeding ASDA with takeoff performance calculations can result in violations and compromised safety.
Other declared distances include TORA (Takeoff Run Available), TODA (Takeoff Distance Available), and LDA (Landing Distance Available). Each serves a specific purpose in flight operations and safety, and their values can differ depending on runway features, thresholds, and safety requirements.
Ensure your airport or flight operation always uses reliable, up-to-date declared distances like ASDA for optimal safety, regulatory compliance, and efficient flight planning. Contact us to streamline your aviation data management.
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