Definition
Under ICAO terminology, Landing Distance Available (LDA) is the length of runway declared available and suitable for the ground run of an aeroplane landing. It begins at the threshold and ends at the point where the runway is no longer usable for the landing rollout.
Plain English
The usable length of runway you actually have to land on and stop, measured from the landing threshold to the end of the usable surface.
Context Anchor
Seen in airport runway data, performance planning, and declared-distance information for a specific runway.
Derivation
ICAO is the International Civil Aviation Organization, the United Nations body that sets global aviation standards. The phrase 'declared distances' (LDA, TODA, TORA, ASDA) comes from ICAO Annex 14 and is the international framework for stating how much runway is actually usable for each phase of operation. Knowing it's an ICAO term flags that this is the international definition, which can differ from the FAA's domestic usage of the same letters.
Why Pilots Care
It tells you whether a given runway meets your aircraft's landing performance requirements, directly affecting go/no-go decisions and safety margins.
Intuition Check
Do not assume “available” means the full paved runway you can see. Here, it means the runway length officially published as usable for landing and stopping.
Example Sentence 1
With a displaced threshold on Runway 27, the LDA was 5,800 feet even though the full pavement measured 6,400 feet.
Example Sentence 2
On the wet runway the Landing Distance Available was reduced, so the crew selected a longer runway.