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6.1 GENERAL

Many different types of search patterns are available to SAR units and in conjunction withthe Co-ordinator Surface Search (CSS) an appropriate pattern to suit the conditionswould be put into operation. Most of the following examples are suitable for either air orsurface units, but in all cases the navigator of the search craft will play a ‘key’ role.

The majority of searches take place within defined limits, depending on the target’scapability and endurance. Individual search units are usually designated a specific areaand the navigator will need to plot these extreme boundaries before instigation of thepattern.

Obviously the type of pattern and track space employed should reflect the nature and sizeof target as well as taking into account the prevailing weather conditions, especially thestate of visibility. Where more search units are employed the accuracy is generallyincreased and / or the area of coverage is increased.

a) EXPANDING SQUARE SEARCH PATTERNS – 1 SHIP

The expanding square search pattern can beemployed by either surface vessels or aircraftsearch units. Where more than one aircraft isinvolved, they would fly at different heights and onheadings 45o off the original.

The CSP begins at the probable location of thetarget and expands outward in concentricsquares. Accurate navigation is required tomonitor the ship’s position towards coursealteration points.

(All course alterations being 90o).

The track spacing which will vary depending onvisibility and sea conditions relative to the typeof target.

Part

IIChapter 6SEARCH PATTERNS

12 miles

4 miles

12 m

iles

4 m

iles

8 miles

8 m

iles

16 m

iles

16 miles

DATUM

App

roac

h

Cour

se

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b) SECTOR SEARCH – 1 Ship

The sector search pattern is employed when the position of the target is knownwith reasonable accuracy and the search is over a small area, as inmanoverboard, or where the casualty has been sighted and then lost.

A suitable marker is used as reference, and dropped at the most likely position ofthe target, i.e. smoke float or beacon. All turns are 120o to starboard. Startpattern at datum. This pattern gives a very high probability of detection close todatum and spreads the search over the probable area quickly.

Upon completion of the first search, re-orientate the pattern 30o to the right andre-search as shown by the dashed line.

The use of timeinstead of miles fordetermining tracespace/ legs maybe moreappropriateespecially for aman overboardincident

1202 Miles

2 Miles

2 Miles

Datum

Firs

t Leg

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4 miles

Datum

4 miles

4 miles

4 miles

4 miles

Dire

ctio

n of

drif

t

Track 2 Track 1

10 miles 10 miles

Width covered by search – 24 miles

Leng

th c

over

ed b

y se

arch

–24

mile

s

3 miles Leng

th c

over

ed b

y se

arch

–20

mile

s

Datum

3 miles

3 miles

3 miles

3 miles

Dire

ctio

n of

drif

t

Track 4 Track 2

Width covered by search –25 miles

Track 1 Track 3

3 miles

3 miles

c) PARALLEL SEARCH PATTERN

Used when the search area is large or where only approximate location isknown and uniform coverage is necessary.

PARALLEL SEARCH – 2 ships

PARALLEL SEARCH – 4 ships

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Ship’s course as directed by OSC

d) CO-ORDINATED CREEPING LINE SEARCH

(1 Ship and 1 Aircraft)

The coordinated creeping line search combines the use of both aircraft andsurface unit(s). The surface unit proceeds along the major axis of the searcharea while the air unit(s) plan their advance to match the ship’s movement.

Note: Fixed winged aircraft (other than seaplanes) can only locate, effectivecommunications can subsequently lead to recovery by the surface units.

Greater accuracy is achieved with increased unit numbers. Aircraft would tend tofly at a height which would permit visible detection. However, where more thanone aircraft is employed a varied height for each above surface level would be inthe interest of air collision avoidance.

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e) PARACHUTE FLARE SEARCH

This combines the use of helicopter and fixed wing to commence a search atnight. This should be only used at the discretion of SMC. (Ref. Part III - Pagevii – SP 1 – Parachute Flare Search).

§ One Maritime Search Unitwith single vessel and an aircraft dropping flares overhead. (Ref. Part III -– Page vii – SP 2 - Parachute Flare Search - 1-Maritime Search Unit)

§ Several Maritime Unitswith a number of vessels and an aircraft. (Ref. Part III - Page viii – SP3 -Parachute Flare Search - Several Maritime Units).

f) ELECTRONIC SEARCH PATTERNS

This will be used when it is known or believed that a ship or other craft orpersons in distress are equipped with radio communication equipment orEPIRB. Electronic search will be conducted at high altitude and low altitude.(Ref. Part III - Page ix – SP 4 - Aural Search and Page x – SP 5 - MeterReading Search).

g) RADAR COORDINATED CREEPING LINE SEARCH

This procedure can be performed by one or more aircraft. The aircraft or theleading aircraft is tracked by the surface unit's radar.