What is runway lead-in lighting?
Groups of lights that mark a straight or curved approach path to the runway, so the pilot can follow it by eye from one group to the next.
Runway lead-in lighting gives visual guidance along a chosen approach path. It is a series of light groups placed along the path, each one positioned so that the pilot can see the next group ahead. The path may be straight, curved or both. It extends from a point set by the appropriate authority to the point where the approach lighting, or the runway and its lighting, comes into view.
It is used where a normal straight-in approach is not suitable. The usual reasons are to keep the aircraft clear of high terrain or obstacles, or away from a noise-sensitive area. The lights are normally flashing white, and steady lights may be added, so the groups can be picked out clearly against the surroundings. ICAO recommends at least three lights in each group, groups no more than about 1,600 m apart, and, where practicable, lights that flash in sequence toward the runway.
Lead-in lighting guides the aircraft’s track over the ground, not its height. It leads the pilot to the point where the approach lighting or the runway itself takes over. The descent slope still comes from other aids, such as a PAPI, a VASI or the instrument approach.
Frequently Asked Questions
Q1What is runway lead-in lighting?
Runway lead-in lighting is a set of light groups that mark a defined approach path to the runway. The pilot follows the lights from one group to the next, along a path that can be straight, curved or both.
Q2Why is lead-in lighting used?
It is used where the normal straight-in approach is not suitable, for example to keep an aircraft clear of high terrain or obstacles, or away from a noise-sensitive area. The lights show the pilot the safe path to follow by eye.
Q3How are the lights arranged?
The lights are placed in groups along the path. Each group is positioned so the pilot can see the next group ahead while following the one before. A group has at least three lights in a cluster or a line across the path. They are normally flashing white and, where practicable, flash in sequence toward the runway. ICAO recommends groups no more than about 1,600 m apart.
Q4How is it different from an approach lighting system?
An approach lighting system sits on the extended runway centreline and helps the pilot line up in the last stretch to the runway. Lead-in lighting can start much further out and follow a path that bends. It leads the aircraft to the point where the approach lighting or the runway takes over.
Q5Does lead-in lighting show the descent slope?
No. It gives guidance on the track over the ground, not on the height. The pilot reads the descent slope from other aids, such as a PAPI, a VASI or the instrument approach.
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