Definition
White lights placed along both sides of a runway to mark its lateral boundaries at night and in low-visibility conditions. On instrument runways, the last 2,000 feet (or half the runway length, whichever is less) of the lights on the departure end appear yellow when viewed from the landing direction, signaling the runway is ending. Runway-edge lights are classified by intensity as HIRL (high intensity), MIRL (medium intensity), or LIRL (low intensity).
Plain English
The two parallel rows of white lights running along the sides of a runway. They show the pilot where the paved surface begins and ends so the airplane can be lined up and kept on the runway in the dark or in poor visibility.
Context Anchor
Seen during night approaches, landings, takeoffs, and taxiing onto or off a runway.
Why Pilots Care
They prevent runway excursions by showing exactly where the pavement ends, especially at night or in fog.
Intuition Check
Runway-edge lights do not show the center of the runway and they do not mean the runway is cleared for landing. They only mark the runway edges so the pilot can see the runway’s outline.
Example Sentence 1
On the night approach, the pilot used the runway-edge lights to judge alignment and flare height during the landing.
Example Sentence 2
Near the departure end, the white runway-edge lights change to amber to warn of the remaining runway distance.