How are stop bar lights spaced and positioned?
A red row across the full width of the taxiway at the holding position, with extra lights beside it.
A stop bar is a row of red lights across the taxiway at the holding position, showing toward the approaching aircraft. The lights are uniformly spaced at not more than 3 m across the taxiway width (ICAO Annex 14), so the number of lights depends on how wide the taxiway is and the bar leaves no gap to pass through.
Where the bar is made of inset lights, additional elevated lights can be added, one each side of the taxiway and at least 3 m from its edge, to make the bar easier to see. The bar is switched by air traffic control, and while it is lit the centreline lights beyond it are extinguished.
Steady red across the taxiway. Switched by ATC to command a stop.
Flashing yellow beside the taxiway. A warning that a runway is ahead.
Frequently Asked Questions
Q1What is a stop bar?
A stop bar is a row of steady red lights across the taxiway at a holding position, showing toward the approaching aircraft. It is switched on by air traffic control to hold traffic and off to release it, so it is a command to stop for as long as it is lit.
Q2Where is a stop bar positioned?
Across the taxiway at the point where traffic is meant to stop, which is the holding position. It sits on the aircraft side of the runway, with the holding position marking and the red mandatory sign repeating the same message. Confirm the exact offset from the marking in the current edition.
Q3How far apart are stop bar lights?
Uniformly spaced across the width of the taxiway, at not more than 3 m between lights under ICAO Annex 14. The number of lights therefore depends on the taxiway width, and the bar must span the full width so no gap is left for an aircraft to pass.
Q4What are the additional elevated lights?
Where a stop bar is made of inset lights, extra elevated lights can be added, one each side of the taxiway, to make the bar easier to see. Under ICAO Annex 14 these are placed at least 3 m from the taxiway edge, and they show red toward the approaching aircraft like the bar itself.
Q5What happens to the centreline lights beyond a lit stop bar?
They are extinguished while the bar is lit, so no green path leads past a red bar. Annex 14 sets a minimum length for the extinguished section, 90 m in the wording most editions use. When the bar goes out, the centreline lights come on again. See the stop bar control entry.
Q6Where are stop bar dimensions defined?
In ICAO Annex 14 Volume I (Chapter 5, stop bars) and the Aerodrome Design Manual Part 4, and for FAA-regulated airports in FAA AC 150/5340-30 and the project specification. FAA figures differ in detail, so always confirm against the current edition.
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