Method

Building a search area from a route

When someone is overdue on a known track, the search area is not a circle around a point — it is a corridor along the route they intended to fly or steam.

How the corridor is built

Start with two fixes: where they were last known to be, and where they were going. The line between them is the intended track.

The corridor is that track widened and extended. A typical construction takes 10 NM either side of the centreline and carries it 5 NM beyond each fix, because an aircraft or vessel that has come down does not stop neatly at the departure or destination point.

• A 77 NM track becomes an 87 NM corridor once extended
• 10 NM either side makes it 20 NM wide
• Divided into 10 × 10 NM boxes, that is 2 across and 9 along
• The last column is a 7 NM remainder — the length rarely divides evenly

Why boxes, not one big area

A 1,740 square nautical mile corridor is not something you assign to a crew. Boxes are. Each box is a unit of work that one asset can be tasked with, searched to a known coverage, and marked complete — so the coordinator can see what has been covered and what has not.

A tasking then names its box, and the crew flies a standard pattern inside it: creeping line ahead, expanding square or a sector search, depending on the terrain and what is known about the subject.

In RSCUE

RSCUE includes an ISP grid builder alongside the eight standard search patterns and freeform pattern drawing. The corridor and its boxes are drawn on the operational map, and taskings reference the box they belong to.

You can see it working in the console on the front page — switch the map to ISP and the corridor, its boxes and the three tasked boxes are drawn from these numbers.