How do holding position markings, signs and lights work together?
No single cue holds an aircraft short of the runway. A yellow marking, a red sign and, at night, a stop bar and guard lights are placed at the same line, so a pilot who misses one still meets the others.
A runway holding position is shown by several cues at the same place. Because a missed hold is a runway incursion, the system is built so that no one cue has to work on its own.
1Marking and sign: the daylight pair
The marking is two solid and two dashed yellow lines across the taxiway, with the solid lines on the side where the aircraft waits. Beside the taxiway, on both sides, a white-on-red mandatory sign names the runway ahead. Both are read by day. The sign is retroreflective or internally lit, so it stays in use at night, and the marking may be made retroreflective as well.
2Lights: the night and low-visibility pair
A stop bar, a row of steady red lights across the taxiway, is switched on to hold traffic and off to release it. Runway guard lights, flashing yellow, warn that the runway ahead may be active. There are two lights on the left and two on the right of the taxiway, side by side as the pilot sees them, and the two in each pair flash alternately. They are often at the same position, but each carries its own instruction.
3Interlocked with the centreline
Green centreline lights lead up to the hold. While the stop bar is lit, the centreline lights beyond it are off for a set distance (at least 90 m under Annex 14), and they come on only when the bar is switched off. The lit path itself ends at the bar, so a pilot cannot follow a green line past a red one.
4One line, one meaning
The sign stands level with the marking, the stop bar is across the taxiway where traffic is to stop, at or just short of the marking, and the guard lights are at the same position, so the cues agree on where to stop. If a stop bar is off or not fitted, the marking and sign still mark the limit. At a set-back CAT II or III position the marking is Pattern B and the sign adds the category.
| Cue | What it is | Where | What it tells the pilot |
|---|---|---|---|
| Marking | Two solid, two dashed yellow lines | Across the taxiway, solid on the holding side | Hold here |
| Sign | White inscription on red | Each side, level with the marking | Mandatory stop, runway named |
| Stop bar | Steady red lights | Across the taxiway at the position | Stop until ATC switches it off |
| Guard lights | Flashing yellow, two each side, alternating | Left and right of the taxiway at the position | Runway ahead may be active |
| Centreline | Green, off beyond a lit bar | Along the taxiway | Lit path ends at the bar |
Frequently Asked Questions
Q1Why are there so many cues at one holding position?
A missed hold is a runway incursion, and any single cue can fail: paint wears, a sign is hidden, lights are off. Layering a marking, a sign and lights at the same line means the others still tell the pilot where to stop.
Q2Which side of the marking are the solid lines on?
The solid lines are on the side where the aircraft waits, and the dashed lines are on the runway side. A pilot approaching from the taxiway therefore meets the solid lines first.
Q3What is the difference between a stop bar and runway guard lights?
A stop bar is a row of steady red lights across the taxiway that commands a stop and is switched on and off by air traffic control. Runway guard lights are flashing yellow lights, two side by side on each side of the taxiway and flashing alternately, that warn the pilot that the runway ahead may be active. They are often at the same holding position but carry different instructions.
Q4What happens to the centreline lights at a stop bar?
They are interlocked with it. While the stop bar is lit, the green centreline lights beyond it are off, and when the bar is switched off to release traffic those lights come on. The lit path itself stops at the bar.
Q5What if the stop bar is off or not installed?
The marking and the mandatory sign still show the holding position. An aircraft or vehicle still needs clearance from air traffic control to go beyond it onto the runway, whether or not a stop bar is fitted.
Q6What changes at a CAT II or III holding position?
The position is set farther back to keep aircraft clear of the protected ILS area. It uses the ladder-style Pattern B marking and a sign that adds the category after the runway designator.
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