Definition
The red lights forming the outermost rows on each side of an Approach Lighting System with Sequenced Flashing Lights (ALSF-2), located in the final 1,000 feet before the runway threshold. They mark the sides of the touchdown zone area within the approach lighting system and serve as one of the visual references a pilot must see, in addition to the runway threshold or markings, to descend below the Decision Altitude or Decision Height on a Category I, II, or III ILS approach.
Plain English
Two rows of red lights along the sides of the approach lighting system, in the last 1,000 feet before the runway. Spotting them on an instrument approach is one of the specific cues a pilot is allowed to use to legally continue down below decision altitude.
Context Anchor
Seen in instrument approach and visibility requirements, especially when deciding whether the runway environment is visible enough to continue lower near the runway.
Derivation
Called 'red side row bars' because the lights are red, arranged in rows running along each side of the approach lighting centerline, forming bar-like lines either side of the touchdown area.
Why Pilots Care
They confirm the location of the runway threshold and help prevent landing short of the pavement.
Grounding Statement
If you come out of cloud close to the runway and see red light bars on both sides of the approach lights, they are telling you that the runway is very near and centered ahead.
Intuition Check
Do not assume these are painted red markings or runway edge lights. Red side row bars are red light bars that are part of the approach lighting system before the runway threshold.
Example Sentence 1
Breaking out just above minimums, the captain called the red side row bars in sight and continued the approach below DA.
Example Sentence 2
Red side row bars appeared on either side of the centerline lights during the low-visibility landing.