What is lead-off lighting?
Alternate green and yellow taxiway centre line lights on an exit taxiway — green first at the runway centre line, yellow last at the edge of the ILS/MLS critical/sensitive area or inner transitional surface. They guide a landing aircraft clear of the runway and show where the protected area ends.
Lead-off lights are the counterpart to lead-on lights: instead of guiding an aircraft onto the runway, they guide a landing aircraft off it, along the exit route back toward the taxiway system. Like lead-on lights, they're not a separate fixture type — they're a functional stretch of taxiway centre line lighting, distinguished by colour so it stands apart from the ordinary green run of centre line lights further down the taxiway.
1The alternating stretch
Lead-off lights are installed as alternate green and yellow lights along the exit taxiway centre line. The first light is always green, at or near the runway centre line, and the light nearest the far limit is always yellow. The alternating stretch runs to the perimeter of the ILS/MLS critical/sensitive area or the lower edge of the inner transitional surface, whichever is farther from the runway centre line. Beyond that point the lights are all green — ordinary taxiway centre line lighting.
2Why the colour changes
The alternating pattern tells the pilot where the protected area ends. While the lights alternate, the aircraft is still on the runway or inside the ILS/MLS critical/sensitive area or the inner transitional surface; only when the lights turn solid green is it clear of that area. It is also a sensitive stretch, so aircraft and vehicles should avoid stopping there without ATC approval.
Frequently Asked Questions
Q1What is lead-off lighting?
Alternate green and yellow taxiway centre line lights on an exit taxiway, starting with a green light near the runway centre line and ending with a yellow light at the perimeter of the ILS/MLS critical/sensitive area or the lower edge of the inner transitional surface, whichever is farther from the runway centre line. They guide a landing aircraft clear of the runway.
Q2Is lead-off lighting a separate fixture type?
No. It's not a separate fixture — it's a functional stretch of ordinary taxiway centre line lighting, distinguished by its alternating colour so it stands apart from the ordinary green run further down the taxiway.
Q3Where does the alternating colour pattern end?
At the perimeter of the ILS/MLS critical/sensitive area or the lower edge of the inner transitional surface, whichever is farther from the runway centre line. The last alternating light, nearest that perimeter, is always yellow; beyond it the lights are all green.
Q4Why does the colour alternate instead of staying green?
To show where the protected area ends. While the lights alternate, the aircraft is still on the runway or inside the ILS/MLS critical/sensitive area or inner transitional surface; solid green means it is clear of that area.
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