Definition
A runway status light system consisting of a row of in-pavement red lights installed along the runway centerline near the departure end of the takeoff position. The lights illuminate automatically, without controller input, when the runway is unsafe for takeoff -- typically because another aircraft is crossing or occupying the runway, or an arrival is too close. When illuminated, they signal the pilot in takeoff position to hold and not begin the takeoff roll.
Plain English
Red lights set into the runway just ahead of an aircraft lined up for takeoff. If they turn on, the runway is not safe to use -- stop and wait. They switch on by themselves, based on what other aircraft are doing.
Context Anchor
You may see Takeoff Hold Lights after entering the runway for departure, especially at larger airports equipped with runway status light systems.
Why Pilots Care
They provide an immediate visual cue that helps prevent runway incursions and potential collisions during the critical takeoff phase.
Grounding Statement
Picture an aircraft lined up on the runway: if red lights appear ahead in the pavement, they are warning the pilot not to take off into a possible conflict.
Intuition Check
Do not assume dark Takeoff Hold Lights mean “cleared for takeoff.” Red means stop or hold; dark only means the automatic warning is no longer showing.
Example Sentence 1
Lined up on Runway 28R, the crew saw the takeoff hold lights illuminate and immediately advised tower they were holding position.
Example Sentence 2
At busy airports the takeoff hold lights give an extra layer of protection during night and low-visibility operations.