What are runway edge lights and why are they important?

• A. Edge lights outline runway boundaries for night/low visibility operations.
• B. They provide vertical descent guidance on approach.
• C. They indicate the runway midpoint to the pilot.
• D. They illuminate only in daylight.

Answer: (A)

Runway edge lights are there to clearly mark the sides of the usable runway surface, so a pilot can see where the pavement begins and ends, even when it’s dark or visibility is poor. This boundary definition helps you keep the aircraft aligned with the runway and avoid drifting off the edges during approach, landing, and rollout, which is crucial for safety in low-visibility conditions. They’re not meant to provide vertical descent guidance—that function comes from systems like PAPI or VASI. They also don’t indicate the runway midpoint—that role belongs to centerline lighting. And they’re not daylight-only; edge lights are designed to be visible at night and in reduced visibility to support safe operations.