Definition
Two rows of transverse light bars placed symmetrically about the runway centerline in the touchdown zone of a precision instrument runway. The lights extend from 100 feet beyond the landing threshold to 3,000 feet beyond the threshold, or to the midpoint of the runway, whichever is less. They are part of the approach and runway lighting system used to mark the area where an aircraft should first make contact with the runway during a precision approach.
Plain English
Two rows of white lights set into the first part of the runway to show the pilot exactly where the aircraft should touch down during a low-visibility landing.
Context Anchor
Seen in runway lighting descriptions, instrument approach information, and inoperative lighting notes for a runway.
Derivation
The name describes the area being lit — the touchdown zone, which is the segment of the runway where the wheels are intended to first touch down. The term is built directly from its function rather than from a foreign root.
Why Pilots Care
They provide precise visual cues for the intended landing point, helping pilots maintain alignment and avoid landing too far down the runway in low-visibility conditions.
Intuition Check
Touchdown zone lights do not mark one exact spot where the airplane must land. They mark the runway area intended for touchdown.
Example Sentence 1
The crew confirmed the touchdown zone lights were on before beginning the approach in low visibility.
Example Sentence 2
TDZL are part of the runway lighting system that activates with the approach lights during night or instrument operations.