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In order that surface units, and especially merchant ships on-scene, will be able to search

effectively, in conjunction with SAR aircraft when available, it is essential that search patterns

and procedures should be preplanned to enable merchant ships of all flags to co-operate incoordinated operations with the minimum difficulty and delay. To achieve this aim, a number of

search patterns to meet varying circumstances have been established.

Available search patterns are as follows:1. Expanding square search: for use by one ship -2. Sector search: for use by one ship (special cases - man overboard, etc.)

3. Parallel track: for use by two ships

4. Parallel track: for use by three ships

5. Parallel track: for use by four ships

6. Parallel track: for use by five or more ships

7. Ship/aircraft coordinated search: for use by ship and aircraft

EXPANDING SQUARE SEARCH

A type of search pattern suitable for asingle ship which should search outward

in expanding squares from the datum.

Datum - The most probable position of thesearch target at a given time, taking into

account the expected effect of drift since

the initial position of the incident wasestablished.

Sector Search Pattern1 Ship

For use when position of search target is known

within close limits, with a small probable area.

Examples.- (a) man overboard - ship returnsimmediately to datum.

(b) search target is once sighted and then lost -

ship heads for datum.

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PATTERN 2Parallel track search - 2 ships

Directionof drift

DATUMS miles S miles

S miles S miles S miles

Track 2 Track 1

PATERN3

Parallel track search - 3 ships

Direction

of drift

DATUM

S miles S miles

S miles S miles S miles

Track 2 Track 1 Track 3

These search patterns give,

in general, good visual

coverage of the Sea.However, in circumstances

in which the searching

speed is slow, the formation

on which the datum is basedis incomplete or unreliable,

or hen high drift rates are

encountered, they haveinevitable limitations. o an

extent, these can be

compensated for by the

arrival of additional archunits, recomputing datum

and the most probable areaperiodically, d expanding

the search area more in one

direction than in another.

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PATTERN 4

Parallel track search -- 4 ships

Direction

of drift

DATUMS miles S miles S miles

S miles S miles S miles S miles

Track 3 Track 4 Track 2 Track 1

PATTERN 6

Co-ordinated creeping line search 1 ship and 1

aircraft

Ships course as directed by OSC

The track spacings (S) shown

in figure 5-6 are

recommended for e with allthe search patterns shown in

this Manual except for the

sector arch (pattern la).

Figure 5-6 takes into accountthe type of search object d

the meteorological visibility.Track spacings may bedecreased slightly, wever, to

increase the probability of

detection, or may beincreased htly to increase the

area covered in a given time.

Other factors may o beconsidered, including sea

condition, time of day,

position of the I effectiveness

of observers, etc.

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Asian Institute of Maritime Studies

ACTIVITY

1 & 2

KINDS OF SEARCH PATTERN

MERSAR

BY:

PANGANIBAN, RABROIE

MT32-C5