runway-end identification lights
runway-end identification lights (REIL)
An airport lighting facility in the terminal area navigation system consisting of one flashing white high-intensity light installed at each approach end corner of a runway and directed toward the approach zone. These lights, which may be omnidirectional or unidirectional, enable the pilot to identify the threshold of a usable runway. The lights emit red light toward the runway to indicate the end of the runway to a departing aircraft and green outward from the runway end to indicate the threshold to landing aircraft. They are effective for identification of a runway surrounded by a preponderance of other lighting; identification of a runway that lacks contrast with the surrounding terrain; and identification of a runway during reduced visibility.