Definition
A pair of alternately flashing yellow lights installed at taxiway/runway intersections to warn pilots and vehicle drivers that they are about to enter or cross an active runway. They may be installed either elevated on each side of the taxiway (elevated runway guard lights) or in-pavement across the taxiway centerline (in-pavement runway guard lights), and they serve as a clear visual cue that a hold-short point is ahead.
Plain English
Flashing yellow lights placed where a taxiway meets a runway. They flash to remind you that a runway is just ahead, so you stop and check before going any further.
Context Anchor
Seen while taxiing near a runway, especially at taxiway/runway intersections and in low-visibility airport movement systems.
Derivation
The name describes the function directly: lights that 'guard' the runway by alerting anyone approaching it. No deeper origin needed.
Why Pilots Care
They provide a clear visual warning that reduces the risk of runway incursions, especially at night or in low visibility.
Intuition Check
Do not read “guard” as meaning the lights give permission or control traffic by themselves. They are a warning marker; clearance still comes from air traffic control when the airport is controlled.
Example Sentence 1
As we approached the hold-short line, the runway guard lights were flashing on either side of the taxiway, so I stopped and waited for our crossing clearance.
Example Sentence 2
During night operations the runway guard lights made the hold-short line easy to identify from the taxiway.