Aviation and Airport Operations: Surfaces, Declared Distances and Safety
This domain tests aerodrome geography, declared distances and the safety procedures that surround runway use.
Aerodrome surfaces and distances
- Runway strip: the area containing the runway and stopway, kept clear of obstacles.
- RESA: ICAO Annex 14 recommends 240 m length for code 3 and 4 runways (90 m for code 1 and 2), at least twice the runway width.
- Declared distances: TORA is the take-off run available; TODA is TORA plus clearway; ASDA is TORA plus stopway; LDA is the landing distance available and is reduced when the threshold is displaced.
- A clearway is obstacle-free airspace and must not exceed half of TORA; a stopway is a prepared surface able to support the aircraft during an accelerate-stop.
- Obstacle limitation surfaces: approach, take-off climb, transitional, inner approach, inner horizontal, conical, outer horizontal.
- PAPI: two red and two white on slope; more than two red means below the approach path, more than two white means above it.
Movement area
Holding position markings protect runway strips and ILS critical areas; aerodrome emergency plans are exercised regularly; RFF category follows aircraft size and movement numbers; FOD and bird control are continuous duties.
Worked example
A runway is 3,000 m long, with a 150 m clearway and a 60 m stopway, and the threshold is displaced 200 m. TORA is 3,000 m; TODA is 3,150 m; ASDA is 3,060 m; LDA is 2,800 m. The clearway check passes because 150 m is well under half of TORA.
Traps
Treating TODA as TORA; swapping stopway and clearway; forgetting that a displaced threshold reduces LDA but not TORA; reading a PAPI as all-white when the aircraft is low.