What is lead-on lighting?
Green taxiway centre line lights that continue from a stop bar toward the runway — interlinked so that the two can never both be lit at once. The stop bar holds; the lead-on lights lead the aircraft on, but only after it's cleared to enter.
Lead-on lights are the stretch of green taxiway centre line lighting that continues from a stop bar toward the runway, on the runway side of the runway-holding position, leading a cleared aircraft onward. They're not a separate light fixture type in their own right — they're an ordinary segment of taxiway centre line lighting that happens to sit in this sensitive stretch and is switched as a unit with the stop bar.
1The stop bar holds
A stop bar is a row of unidirectional red lights, normally inset in the pavement, installed across the full width of the taxiway at the holding position and showing red toward approaching traffic. When the stop bar is switched on, it signals a mandatory stop — no aircraft or vehicle proceeds past it, even if a clearance has been received, until it's switched off.
2The lead-on lights take over
The lead-on lights are interlinked with the stop bar so that the two can never be lit together: while the stop bar is on, the lead-on lights beyond it are off (Annex 14 requires centre line lights beyond a lit stop bar to be extinguished for at least 90 m). Only once the aircraft has clearance to enter the runway and the stop bar is switched off do the lead-on lights illuminate, giving a continuous lit path onward to the runway. Where that stretch lies inside the ILS/MLS critical/sensitive area or the inner transitional surface, it may be coded alternately green and yellow; follow the applicable standard and the aerodrome’s lighting design.
Frequently Asked Questions
Q1What is lead-on lighting?
Green taxiway centre line lights that continue from a stop bar toward the runway, interlinked with the stop bar so the two can never both be lit at once.
Q2How does the interlock with the stop bar work?
While the stop bar is on, the lead-on lights beyond it stay off. Annex 14 requires the centre line lights beyond a lit stop bar to be extinguished for at least 90 m. Only once the aircraft has clearance to enter the runway and the stop bar switches off do the lead-on lights illuminate, giving a continuous lit path to the runway.
Q3Is lead-on lighting a distinct fixture type?
No. It's an ordinary segment of taxiway centre line lighting that happens to sit in this sensitive stretch and is switched as a unit with the stop bar.
Q4Does lead-on lighting ever alternate colour?
It can. Where the lead-on stretch lies inside the ILS/MLS critical/sensitive area or the inner transitional surface, it may be coded alternately green and yellow; follow the applicable standard and the aerodrome’s lighting design.
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