Definition
A pair of synchronized flashing white lights installed on each side of the runway threshold, used to provide rapid and positive identification of the approach end of a particular runway. REILs may be either omnidirectional or unidirectional facing the approach area, and are commonly installed at runways without other approach lighting systems or where the threshold might otherwise be hard to distinguish.
Plain English
Two bright flashing lights, one on each side of the start of the runway, that flash together to help pilots quickly spot which runway to land on.
Context Anchor
You may see REIL while approaching a runway at night, in reduced visibility, or at an airport where other lights make the runway harder to identify.
Why Pilots Care
Allows pilots to quickly confirm the correct runway end, reducing the risk of landing short or on the wrong surface at night.
Intuition Check
Do not read “runway end” as the far end you roll toward after landing. In this use, REIL identify the approach end—the end where you begin landing.
Example Sentence 1
On the night approach into the small regional airport, the REILs flashing on either side of the threshold made the runway easy to pick out from the surrounding road lights.
Example Sentence 2
REIL are especially useful at uncontrolled airports where runway identification can be challenging in darkness.