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Declared distances calculator

ToolAnnex 14 §2.8, Attachment A §3Free

TORA, TODA, ASDA and LDA. The trap is the displaced threshold — it reduces the landing distance in one direction only.

Four distances, one runway

Take-off run available is the runway. Take-off distance available adds any clearway. Accelerate-stop distance available adds any stopway. Landing distance available is what remains for the landing ground run.

Clearway and stopway are different things and are not interchangeable. A clearway is airspace over ground you do not have to be able to stop on. A stopway is surface you do.

The displaced threshold trap

A displaced threshold reduces landing distance available for approaches to that threshold, and only for that direction. The reciprocal direction is untouched. This is the most common error in a declared-distance table, and it is easy to make because the runway looks symmetrical on the drawing.

Not usable is a value

Where a direction is unavailable for take-off or landing the distance is published as NU. Not zero, not blank. A blank cell in an AIP entry is ambiguous; NU is a statement.

These are the mechanics. For any real runway the State's published AIP entry governs.

Every figure on this page is cited to the paragraph it comes from. Where a value is a Recommendation rather than a Standard, the row says so. Verified against ICAO Annex 14 Volume I, with EASA CS-ADR-DSN and two national transpositions used as cross-checks.

The calculation is the easy part.

Deciding which standard applies to your operation is the job. That is what the programme covers.

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