Definition
Low Intensity Runway Lights (LIRL) are the lowest-brightness category of runway edge lighting installed at airports. They consist of fixed white lights placed along both sides of the runway to mark its edges at night or in reduced visibility. Unlike medium or high intensity systems, LIRL brightness is fixed at one low setting and is not pilot-adjustable.
Plain English
A basic set of white lights along the edges of a runway, used at smaller airports to show pilots where the runway is at night. The brightness can't be turned up or down — it stays on one low setting.
Context Anchor
Seen in airport lighting information, airport diagrams, and night landing or takeoff planning.
Why Pilots Care
Knowing the runway has only LIRL tells you what to expect at night: the runway will appear dimmer than at larger airports, and you can't request brighter lights. This affects how easily you'll spot the runway on a night approach, especially in haze or against city lights.
Intuition Check
Low intensity does not mean the runway is less official or less usable. It means the lights are lower in brightness than medium- or high-intensity runway lights.
Example Sentence 1
The Chart Supplement showed the destination had LIRL only, so the pilot planned to arrive before full dark to make the runway easier to spot.
Example Sentence 2
LIRL provide enough light for visual runway alignment but are dimmer than medium or high intensity systems.