What are runway end identifier lights (REIL)?
A pair of flashing white lights, one on each side of the runway threshold, that make the approach end of the runway easy to find, especially where there is no approach lighting or a lot of other lights around it.
A pilot flying a visual or non-precision approach has to find a runway among roads, buildings, apron lights and dark terrain. REIL give that search a target: two synchronised flashing white lights at the threshold that no other light on the airport looks like.
1What they are
REIL are a pair of flashing lights, one on each side of the runway at the approach end. The two units flash together so they read as a single signal. REIL is the FAA name; ICAO Annex 14 calls the same lights runway threshold identification lights.
2Where they sit
They are set at the threshold, symmetrically about the runway centreline and in line with the threshold, just outside the runway edge, and are aimed toward the approach. They sit alongside the green threshold lights, not in place of them.
3Why they are provided
They are most useful where the threshold is hard to pick out: a runway with no approach lighting, one surrounded by other lights, one with little contrast against the terrain, or any runway in reduced visibility. Annex 14 provides for them at the threshold of a non-precision approach runway where extra conspicuity is needed or other approach lighting aids are not practicable, and where a threshold is displaced and needs extra conspicuity.
4How they flash and are controlled
The flash rate is 60 to 120 flashes per minute, with the two units synchronised. They are switched, and normally set to an intensity step, from the control position, and the monitoring system can report their status like any other runway light.
| Feature | REIL |
|---|---|
| Colour and mode | White, flashing |
| Number | Two per approach end, one on each side |
| Position | At the threshold, outside the runway edge, in line with the threshold (ICAO: about 10 m outside each line of edge lights) |
| Flash rate | 60 to 120 per minute, units synchronised |
| Aimed | Toward the approach |
| Relationship to threshold lights | Added to them, not a replacement |
Frequently Asked Questions
Q1What are runway end identifier lights?
Runway end identifier lights, or REIL, are a pair of synchronised flashing white lights, one on each side of the runway threshold, aimed at aircraft on approach. They help a pilot pick out the approach end of the runway quickly.
Q2How are REIL different from threshold lights?
Threshold lights are steady green lights across the threshold that mark where the usable runway begins. REIL are two flashing white lights beside the threshold that make the end easier to find. REIL are provided in addition to threshold lights, not instead of them.
Q3Is REIL an ICAO term?
REIL is the FAA term. ICAO Annex 14 describes the same idea as runway threshold identification lights: flashing white lights at the threshold, provided at non-precision approach runway thresholds where extra conspicuity is needed or other approach lighting is not practicable, and at displaced thresholds that need extra conspicuity.
Q4Where are REIL installed?
One unit on each side of the runway at the threshold, symmetrically about the runway centreline and in line with the threshold, set outside the runway edge, and aimed toward the approach. Exact positions come from the standard in use.
Q5Does every runway have REIL?
No. They are provided where they help most, such as runways without an approach lighting system, runways surrounded by other lights, or runways with little contrast against the terrain, and where the standard or the aerodrome's operations call for them.
Q6How are REIL controlled and how fast do they flash?
They flash at between 60 and 120 flashes per minute, with the two units synchronised so they appear as a pair. They are switched, and usually set to an intensity step, from the control position, and the control and monitoring system can report their status.
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