Definition
A series of sequenced flashing lights installed on or near the ground along the final approach path to a runway, used to guide pilots visually from a point where the runway is not easily seen — such as over water, featureless terrain, or around obstacles — directly to the runway threshold.
Plain English
A line of flashing lights on the ground that points the way to the runway, helping the pilot find it when the surrounding area makes the runway hard to spot.
Context Anchor
Seen in airport lighting information, arrival planning, and notices about runway lighting, especially for night operations or airports where the path to the runway is not straight or obvious.
Derivation
‘Lead-in’ literally means ‘to lead someone in.’ The lights form a visual path that leads the pilot in to the runway — the name describes exactly what the system does.
Why Pilots Care
Provides reliable visual guidance that helps pilots maintain the correct flight path and safely reach the runway.
Intuition Check
Do not assume lead-in lights are the same as runway edge lights. RLLS lights guide you toward the runway; they do not simply mark the runway surface or edges.
Example Sentence 1
The approach plate noted an RLLS guiding aircraft over the bay to the runway threshold.
Example Sentence 2
When visibility dropped, the RLLS lights gave the crew a clear path to the threshold.