The runway edge lights are white, except on instrument runways yellow replaces white on the last 2,000 feet or half the runway length, whichever is less, to form a caution zone for landings.

Yellow lights on a runway, officially known as Runway Edge Lights in the final 2,000 feet of a displaced threshold or the last 2,000 feet of a runway (whichever is less), serve as a critical visual "caution" zone for pilots. On instrument runways, the standard white edge lights switch to yellow to alert the flight crew that they are rapidly approaching the end of the available landing distance. This color change provides a high-contrast transition that is easily identifiable even in low-visibility conditions or during high-speed night landings. Additionally, yellow lights are found in the Caution Range of the Runway Centerline Lighting System, where they begin to alternate with white lights starting 3,000 feet from the end, and eventually turn solid red for the final 1,000 feet. You will also see yellow "Guard Lights" (often called "wig-wag" lights) at taxiway-runway intersections; these consist of two alternating flashing yellow lamps designed to prevent runway incursions by clearly marking the "hold short" line. In 2026, these lighting systems are increasingly being upgraded to high-intensity LED technology, which provides a sharper, more distinct yellow hue that pierces through heavy fog more effectively than older incandescent bulbs.