Trackline search (non-return) pattern

The Trackline search (non–return) pattern, also referred to as ‘Trackline Single-unit Non return (TSN)’, is used when the only available information is the intended route of the vessel or aircraft. This type of search pattern is often used as an initial search effort due to speed that it can be planned and implemented.

SARTrackline search (non-return)

The Trackline search (Non–return) pattern is a search pattern that follows an intended route from start to finish.

Figure 1. Example trackline search (non–return) pattern

The search pattern can be configured to traverse the route more than once, enabling a greater area to be searched on either side of the intended route.

When multiple traversals are required, the search pattern will return to the end of the route that the search commenced and then follow it to the end again. These subsequent search legs will be parallel and be a specified distance (track spacing) from the first traversal and the intended route.

After the first traversal subsequent traversals are done in pairs so that the final search leg finishes at the end of the intended route.

  1. Intended route

  2. 1 traversal (follows intended route)

  3. 5 traversals (intended route plus 2 per side)