Definition
The length of runway declared available and suitable for the ground run of an aircraft landing. It is measured from the threshold to the end of the runway surface usable for landing rollout.
Plain English
How much runway you actually have to land on and stop, measured from where you can first touch down to where the usable runway ends.
Context Anchor
Seen in airport runway data and landing performance planning, especially at airports that publish declared runway distances.
Derivation
The phrase is plain English. The word 'available' is the key one — it signals that this is the runway length you are actually allowed to use for landing, which may be shorter than the full physical runway if the threshold is displaced or part of the surface is unusable.
Why Pilots Care
Determines whether the runway meets the distance needed for a safe landing given aircraft weight, wind, temperature, and runway condition.
Intuition Check
Do not assume LDA means the entire paved runway is available for landing. It means the officially usable landing length published for that runway.
Example Sentence 1
Before flying into the short strip, she checked the LDA and confirmed her aircraft could land and stop with a comfortable margin.
Example Sentence 2
With a wet runway and tailwind, the effective LDA dropped below the minimum needed, so the crew chose an alternate airport.