How are taxiway fixtures oriented?
Whether a taxiway light is seen from every direction, from two, or from only one comes down to how the fixture is aimed — edge lights show all around, centreline lights follow the line and toe in on curves, and bars face only the aircraft they control.
Orientation is the direction a fixture's main beam points, and how many ways it faces. Two fixtures with the same lamp or LED can look completely different to a pilot depending on how they are aimed: one is seen from the whole taxiway, another only from the aircraft it is meant for. On a taxiway the right answer depends on the job — outline the pavement, guide along a line, or control one approach.
1Edge lights: all around
Taxiway edge lights are fixed blue lights that show up to at least 75° above the horizontal and at all angles in azimuth needed to guide a pilot taxiing in either direction. Because they must be read from every side, the exceptions are deliberate: at an intersection, exit or curve they are shielded as far as practicable so they cannot be seen from angles where they might be mistaken for other lights. See Taxiway Edge Lights.
2Centreline lights: along the line, toed in on curves
On a straight taxiway the centreline beam is aimed parallel to the centreline. Fixtures can face both ways (bidirectional) or one way (unidirectional) depending on how the taxiway is used, and the beam is shaped so the light is visible only from aircraft on or near the taxiway. On a curve, the pilot looks along a chord rather than the tangent, so a beam aimed straight ahead would be seen at a poor angle. Curve fixtures are therefore either wide-beam or toed in toward the inside of the curve. FAA fixture classes make the same split into narrow and wide, unidirectional and bidirectional types. Spacing on the curve is covered in Entry 26.
3Bars: one way only
A stop bar is a set of unidirectional lights showing red toward the aircraft approaching it. Intermediate holding-position lights follow the same idea in yellow (Entry 13). Facing one way is the point: the signal controls only the traffic that has to obey it, and adds nothing for aircraft beyond it or travelling the other way.
| Light | Colour | Orientation |
|---|---|---|
| Taxiway edge light | Blue | All azimuths needed; up to ≥75° elevation; shielded at junctions, exits, curves |
| Centreline, straight | Green | Aligned with the centreline; bidirectional or unidirectional; visible on or near the taxiway |
| Centreline, curve | Green | Wide beam, or toed in toward the inside of the curve |
| Intermediate holding-position lights | Yellow | Unidirectional, toward traffic approaching the position |
| Stop bar | Red | Unidirectional, toward the approaching aircraft |
Frequently Asked Questions
Q1What does fixture orientation mean for a taxiway light?
How the fixture's beam is aimed: which way the main beam points and whether the light faces all around, two ways or one way only. It decides which aircraft can see the light and how bright it looks from the pilot's position.
Q2Which taxiway lights show in all directions?
Taxiway edge lights. Annex 14 calls for fixed blue lights that show up to at least 75° above the horizontal and at all azimuths needed to guide a pilot taxiing in either direction, shielded as far as practicable at intersections, exits and curves.
Q3Why are centreline lights toed in on curves?
On a curve the pilot is looking along a chord, not along the tangent. Turning the beam toward the inside of the curve, or using a wider beam, keeps the light bright for an aircraft that is still approaching the bend.
Q4Which taxiway lights are unidirectional?
Stop bars, which show red toward the approaching aircraft, and intermediate holding-position lights, three fixed yellow lights seen only by traffic approaching the holding position. Centreline lights can be bidirectional or unidirectional, depending on how the taxiway is used.
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