What are different search patterns as per IAMSAR ?

Written by Amit Sharma

Different search patterns:

EXPANDING SQUARE SEARCH
  • Most effective when the location of the search object is known within relatively close limits.
  • The commence search point is always the datum position.
  • Often appropriate for vessels or small boats to use when searching for persons in the water or other search objects with little or no leeway.
  • Due to the small area involved, this procedure must not be used simultaneously by multiple aircraft at similar altitudes or by multiple vessels.
  • Accurate navigation is required; the first leg is usually oriented directly into the wind to minimize navigational errors.
  • It is difficult for fixed-wing aircraft to fly legs close to datum if 5 is less than 2 NM.

 

SECTOR SEARCH (V5)

  • Most effective when the position of the search object is accurately known and the search area is small.
  • Used to search a circular area centred on a datum point.
  • Due to the small area involved, this procedure must not be used simultaneously by multiple aircraft at similar altitudes or by multiple vessels.
  • An aircraft and a vessel may be used together to perform independent sector searches of the same area.
  • A suitable marker (for example, a smoke float or a radio beacon) may be dropped at the datum position and used as a reference or navigational aid marking the centre of the pattern.
  • For aircraft, the search pattern radius is usually between 5 NM and 20 NM.
  • For vessels, the search pattern radius is usually between 2 NM and 5 NM, and each turn is 120˚, normally turned to starboard.

TRACK LINE SEARCH (TS)

  • Normally used when an aircraft or vessel has disappeared without a trace along a known route.
  • Often used as initial search effort due to ease of planning and implementation.
  • Consists of a rapid and reasonably thorough search along intended route of the distressed craft.
  • Search may be along one side of the track line and return in the opposite direction on the other side (TSR).
  • Search may be along the intended track and once on each side, then search facility continues on its way and does not return (TSN).
  • Aircraft are frequently used for TS due to their high speed.

Aircraft search height usually 300 m to 600 m (1,000 ft to 3,000 ft) during daylight or 600 m to 900 m (2,000 ft to 3,000 ft) at night.

About the author

Amit Sharma

Graduated from M.E.R.I. Mumbai (Mumbai University), After a brief sailing founded this website with the idea to bring the maritime education online which must be free and available for all at all times and to find basic solutions that are of extreme importance to a seafarer by our innovative ideas.

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