Definition
A row of in-pavement red lights installed near the departure end of a runway that automatically illuminate to warn an aircraft in takeoff position that the runway is not safe to use, typically because another aircraft or vehicle is on or crossing the runway ahead. When lit, the lights are a mandatory signal to hold position and not begin the takeoff roll.
Plain English
Red lights set into the runway surface that switch on to tell a pilot lined up for takeoff to stop and not go, because something is in the way further down the runway.
Context Anchor
Seen on some towered airport runways while lined up for takeoff or beginning the takeoff roll.
Why Pilots Care
They give an immediate visual warning that prevents runway incursions and potential collisions at the most critical phase of flight.
Analogy
They are like a red stop signal built into the runway, but with one important difference: no red light is not the same as a green light.
Intuition Check
Do not assume “lights off” means “cleared for takeoff.” Red means stop or hold; unlit only means the system is not warning you at that moment.
Example Sentence 1
As we lined up on Runway 27L, the Takeoff Hold Lights illuminated, so we held position and queried the tower before continuing.
Example Sentence 2
Even after receiving takeoff clearance the pilot waited because the takeoff hold lights remained on.