How are lights arranged through a taxiway curve?
Green centreline lights hold a constant distance from the outside edge of the turn, blue edge lights follow both pavement edges, and spacing tightens as the radius shrinks — so the curve reads clearly before the aircraft reaches it.
A curve is where the straight-line cues a pilot relies on stop working. Annex 14, Volume I answers that with two rules working together: the centreline lights keep a fixed relationship to the pavement as the taxiway turns, and the spacing of both centreline and edge lights is tightened so the shape of the turn is visible well ahead of the aircraft.
1Centreline lights on a curve
Centreline lights on a curve continue from the straight portion at a constant distance from the outside edge of the curve, spaced so that a clear indication of the curve is provided. Spacing steps down by radius. For normal operations (RVR 350 m or more) it is 30 m for radii of 900 m or more, 15 m for 401–899 m, and 7.5 m for 400 m or less. Where RVR is below 350 m (CAT II/III) it collapses to 15 m for radii of 400 m or more and 7.5 m below that, and on those tightest curves the 7.5 m spacing is extended 60 m before and after the curve.
2Edge lights on a curve
Edge lights keep marking both pavement edges through the turn, at less than 60 m instead of the straight-section maximum. Annex 14 does not fix a single curve figure; the tighter the radius, the closer the lights, with guidance in ICAO Doc 9157 (Aerodrome Design Manual), Part 4. They stay as near as practicable to the pavement edge, or outside it by not more than 3 m, following the edge as built. The full edge-light rules are covered in the taxiway edge-light arrangement entry.
| Element | Straight section | Through the curve |
|---|---|---|
| Centreline, normal operations (RVR ≥350 m) | ≤30 m | 30 m (R ≥900 m) · 15 m (401–899 m) · 7.5 m (≤400 m) |
| Centreline, RVR <350 m (CAT II/III) | ≤15 m | 15 m (R ≥400 m) · 7.5 m (<400 m), extended 60 m before and after the curve |
| Edge lights | Uniform, ≤60 m | <60 m — tighter radius, closer spacing |
| Centreline position | Along the taxiway centreline | Continues at a constant distance from the outside edge of the curve |
| Edge position | At the pavement edge, or ≤3 m outside it | Same, following the edge as built |
Frequently Asked Questions
Q1How are lights arranged through a taxiway curve?
Green centreline lights continue from the straight section at a constant distance from the outside edge of the curve, with spacing tightened as the radius shrinks. Blue edge lights run along both pavement edges at less than 60 m so the curve is clearly indicated.
Q2Where are centreline lights placed on a curve?
They continue from the straight portion of the taxiway at a constant distance from the outside edge of the curve, spaced so that a clear indication of the curve is provided.
Q3How does centreline spacing change with curve radius?
For normal operations (RVR 350 m or more): 30 m for radii of 900 m or more, 15 m for 401–899 m, and 7.5 m for 400 m or less. Where RVR is below 350 m (CAT II/III): 15 m for radii of 400 m or more and 7.5 m below that, with 7.5 m spacing on the tightest curves extended 60 m before and after the curve.
Q4Do taxiway edge lights follow the curve too?
Yes. Edge lights continue along both edges of the pavement at less than 60 m. Annex 14 does not fix a single figure; the tighter the curve, the closer the lights, with guidance in ICAO Doc 9157 Part 4. They stay at the pavement edge or not more than 3 m outside it.
See It. Understand It. Then Learn How to Engineer It.
Recognising an AGL system visually is the first step. The next step is knowing how to design, install, test, commission and maintain them correctly.
Build Practical AGL Engineering Skills
Go deeper with structured training from Precision AGL Academy, covering:
Learn how each light, sign and circuit works as part of a complete airport lighting system, not just as an isolated diagram.