Definition
A simplified approach lighting system consisting of seven omnidirectional flashing lights — five sequenced lights spaced along the runway centerline extension out to 1,500 feet from the threshold, plus two lights placed on either side of the runway threshold. The lights flash in sequence from the outermost light toward the runway, helping pilots visually acquire and align with the runway during the final segment of a non-precision instrument approach.
Plain English
A basic set of seven flashing lights that lead a pilot's eye toward the runway end during an instrument approach. Five of the lights line up out in front of the runway and flash one after another toward it; the other two sit beside the runway threshold to mark where the runway begins.
Context Anchor
Seen on instrument approach charts, airport lighting descriptions, and inoperative-components notes for approach procedures.
Derivation
‘Omnidirectional’ comes from the Latin omnis (‘all’) and direction — meaning the lights are visible from all directions, not just from straight ahead. This matters because it tells you the lights can be seen and used even if you’re slightly off the final approach course, unlike directional approach lights that are aimed.
Why Pilots Care
Provides essential visual alignment cues on final approach when other lighting may be inoperative, helping maintain the correct flight path to the runway.
Intuition Check
ODALS does not mean you may approach the runway from any direction. It means the approach lights themselves shine in all directions.
Example Sentence 1
The approach plate noted that ODALS was out of service, so we added the required visibility increase before deciding whether to attempt the approach.
Example Sentence 2
The approach plate noted that the ODALS was available as a visual aid if the primary lighting system failed.