Definition
An instrument approach procedure that allows two aircraft to make simultaneous approaches to closely spaced parallel runways where the runway centerlines are separated by less than 3,000 feet but at least 750 feet. One aircraft flies a straight-in ILS or RNAV approach to one runway, while the other flies an offset approach (typically an LDA with glideslope) whose final course is angled away from the parallel runway. The offset reduces the chance of conflict and allows both approaches to proceed at the same time in instrument conditions.
Plain English
A way for two airplanes to land at the same time on two runways that sit close together. One plane flies straight in. The other flies in at a slight angle, then turns to line up with its runway near the end. The angle keeps the two planes safely apart while both approach in cloud or low visibility.
Context Anchor
You may see SOIA on approach charts, in arrival planning, or in air traffic control instructions at busy airports with close parallel runways.
Derivation
‘Offset’ here means the final approach course is set at an angle to the runway rather than aligned straight with it. ‘Simultaneous’ refers to two approaches happening at the same time, in parallel.
Why Pilots Care
Increases airport capacity and reduces delays at busy airports by allowing more landings per hour while maintaining safety through offset paths and required visual contact.
Intuition Check
Do not read “offset” as “wrong” or “off course.” In SOIA, the offset path is intentional, published, and part of the approved procedure.
Example Sentence 1
ATC cleared us for the SOIA LDA approach to runway 28L while a 737 flew the parallel ILS to 28R.
Example Sentence 2
During the SOIA, the pilot on the offset approach maintained visual separation after passing the offset point.