Definition
Two transverse rows of green threshold lights extending outward from each side of the runway threshold, used as part of certain approach lighting systems (notably ALSF-2 and SSALR) to mark the start of the landing surface for aircraft approaching from the opposite direction during circling or downwind operations.
Plain English
A pair of green light bars at the runway threshold, set out to the sides, that help pilots see where the runway begins.
Context Anchor
Seen in approach lighting discussions and during final approach when using visual slope lights beside the runway.
Derivation
"Downwind" here refers to the direction from which the lights are intended to be visible — opposite the landing direction — not to a pattern leg. The bars are oriented so a pilot looking back toward the threshold from the opposite end of the runway can identify it clearly.
Why Pilots Care
They reduce the chance of misalignment or landing short by giving extra visual reference when primary lights are marginal.
Grounding Statement
Picture two rows of slope lights beside the runway: the downwind light bars are the row or rows closer to the runway threshold.
Intuition Check
Do not read downwind here as the downwind leg of a traffic pattern. In this term, downwind identifies the light bars nearer the runway threshold.
Example Sentence 1
The approach plate noted that the runway was equipped with downwind light bars, giving the crew a clear threshold reference when circling to the opposite runway at night.
Example Sentence 2
Even with the runway edge lights in sight, the downwind light bars confirmed the correct touchdown zone.