What is REIL and where are these lights located?

• A. Radar Echo Identification Lights located at the approach path.
• B. Runway End Identifier Lights located at the runway threshold to help identify the threshold.
• C. Approach Lighting System located at the runway end.
• D. Runway Edge Lights located along the runway shoulders.

Answer: (B)

REIL stands for Runway End Identifier Lights. Their job is to give pilots a rapid, positive cue of where the runway ends, helping identify the threshold during approach, especially in low visibility or at night. They consist of a pair of synchronized flashing lights located at the threshold on each side of the runway, precisely where the landing begins. This placement makes the threshold easy to spot without relying on other lighting systems.

Other lighting systems serve different functions: the approach lighting system creates a path leading to the runway, runway edge lights outline the sides of the runway, and radar-related identifier lights isn’t a standard term for runway lighting. Since REILs are the flashing lights at the threshold used to identify the threshold itself, this option is the correct description.