11.6 Parallel Line Search Pattern
Purpose
To outline the use of parallel line search patterns during search and rescue (SAR) operations involving SLS personnel, services, and assets.
Overview
A parallel line search pattern is a structured search method used to provide uniform coverage across a defined search area.
The pattern is most suited to rectangular or square search areas, particularly where the area of probability is large and the exact location of the person, vessel, craft, or object in distress is not well established.
The National Search and Rescue Manual refers to this type of search pattern as a parallel track search pattern. Within SLSSA SOPs, the term parallel line search pattern is used for consistency with Surf Life Saving terminology.
A parallel line search pattern may be conducted by one or more Search Teams, including vessels, aircraft, vehicles, in-water personnel, or land-based personnel where appropriate.
In South Australia, South Australia Police (SAPOL) is the control agency for all search and rescue activities. SLS personnel may conduct or support parallel line search activity where tasked, authorised, trained, equipped, and operating within approved capability.
Diagram
Definitions
Parallel line search pattern means a search pattern where search legs are conducted in parallel lines across a defined search area.
Search Team means a person, team, vessel, aircraft, vehicle, or other resource tasked to undertake SAR activity.
Search area means the defined area assigned for search activity.
Search leg means one straight section of the search pattern.
Track spacing means the distance between adjacent search legs.
Major axis means the longer side or principal direction of the search area.
Search object means the person, vessel, craft, object, or item being searched for.
Procedure
When to Use
A parallel line search pattern may be used where:
- The search area is large,
- The search area is rectangular or square,
- The location of the search object is not well established,
- The search object may be anywhere within the assigned area,
- Uniform coverage is required,
- Search Teams can safely maintain parallel tracks,
- Track spacing can be maintained,
- Communications can be maintained,
- The search area and pattern have been assigned by the Control Agency or approved SLS command role, and
- SLS resources are capable of safely conducting the task.
Parallel line search patterns are generally suited to open water or relatively open search areas.
Search Planning
Where SAPOL or another authorised Control Agency has assumed control, search planning remains the responsibility of the Control Agency.
SLSSA may support search planning by providing:
- Local beach and coastal knowledge,
- Surf, wind, tide, current, and drift observations,
- Last known position information,
- Search object information,
- SLS resource availability,
- Asset capability and limitation information,
- Communications information, and
- Risk or safety considerations.
SLS personnel must not independently develop or implement a complex SAR search plan where the Control Agency has assumed control, unless directed or authorised to do so.
Pattern Description
The parallel line search pattern is conducted by moving through the search area using a series of parallel search legs.
The search legs should generally be aligned parallel to the major axis of the search area.
The search should normally commence from one corner or assigned start point of the search area.
Successive search legs should be maintained parallel to each other and one track spacing apart.
The search pattern should be conducted in a way that provides consistent coverage and minimises gaps between search legs.
Single Search Team Method
When using a single Search Team, personnel should:
- Confirm the assigned search area.
- Confirm the search object.
- Confirm the start point.
- Confirm the direction of travel.
- Confirm track spacing.
- Confirm search speed.
- Confirm communications arrangements.
- Confirm SITREP requirements.
- Proceed to the assigned start point.
- Commence the first search leg along the assigned direction.
- Maintain observation throughout the search leg.
- Turn at the end of the search leg where safe and appropriate.
- Offset by one track spacing.
- Complete the next search leg in the opposite direction.
- Continue successive parallel search legs until the assigned search area is complete or the search is modified, suspended, or stood down.
- Record the area searched and any observations, sightings, clues, hazards, or limitations.
- Provide updates to the State Operations Centre (SOC) as required.
Where practical, search tracks should be recorded using GPS, mapping, or other available tracking tools.
Multiple Search Team Method
Parallel line searches may be conducted by multiple Search Teams where appropriate.
When multiple Search Teams are involved:
- Each Search Team should be assigned a defined search area or search track,
- Track spacing must be clearly understood,
- Starting points should be separated to avoid overlap or collision risk,
- Communications must be maintained,
- Search Teams must remain aware of each other’s location,
- Overlap should be planned where required,
- Search areas completed by each Search Team must be recorded, and
- The SOC or coordinating role must be updated as search areas are completed.
Where the search area is relatively small, Search Teams may be placed one track spacing apart and search in parallel.
Where the search area is larger, each Search Team may be assigned a separate section of the search area, with an overlap distance included where required.
IRB, RWC, JRB or Other Powercraft Method
Where a parallel line search is conducted by IRB, RWC, JRB, or other approved powercraft, the Search Team should:
- Confirm the search area before entering the pattern,
- Maintain the assigned heading and track spacing,
- Maintain a safe search speed,
- Maintain effective lookout at all times,
- Avoid excessive speed or manoeuvring that reduces detection,
- Maintain awareness of other Search Teams,
- Maintain safe separation from swimmers, in-water personnel, other vessels, and the public,
- Consider wind, tide, current, swell, and drift,
- Consider fuel range and endurance,
- Report any area that cannot be searched safely, and
- Provide SITREPs as required.
Where powercraft and in-water personnel are operating in or near the same search area, specific separation, communication, and safety arrangements must be confirmed before commencing the search.
In-Water Search Team Method
Where a parallel line search is conducted by in-water personnel, the Search Team should:
- Confirm the search area and boundaries,
- Confirm the direction of travel,
- Confirm spacing between searchers,
- Maintain line formation where required,
- Maintain visual or verbal contact where practicable,
- Maintain agreed search speed,
- Maintain awareness of fatigue and exposure,
- Maintain awareness of water movement and drift,
- Avoid entering areas beyond capability,
- Report hazards or limitations,
- Report any areas not searched, and
- Provide SITREPs as required.
In-water parallel line searches should only be undertaken where conditions, supervision, support, and communications are suitable.
Working with Powercraft
Where powercraft and in-water personnel are operating in or near the same search area, specific separation, communication, and safety arrangements must be confirmed before commencing the search.
This may include:
- Clear separation between powercraft and in-water Search Teams,
- Confirmed powercraft operating areas,
- Confirmed communications or hand signals,
- Safe speed near in-water personnel,
- Active lookout,
- Engine safety when close to in-water personnel,
- Emergency stop or withdrawal signals, and
- Immediate modification or cessation of the task if safety cannot be maintained.
Track Spacing
Track spacing should be determined by the Control Agency or search planning role where the SAR operation is under agency control.
Track spacing should consider:
- Search object size,
- Visibility,
- Sea state,
- Surf conditions,
- Wind,
- Glare,
- Observer height,
- Search speed,
- Available Search Teams,
- Search area size,
- Fatigue,
- Probability of detection,
- Available daylight, and
- Operational risk.
If visibility or detection conditions deteriorate, track spacing may need to be reduced or the task may need to be modified.
SLS personnel should report any concern that the assigned track spacing is unsuitable or unsafe.
Visual References and Markers
Search Teams may use visual references, GPS points, mapping tools, buoys, landmarks, or other approved methods to support accurate navigation and coverage.
Where safe and appropriate, a buoy or surface marker may be used to identify a reference point.
Markers must not create additional hazards or interfere with other vessels, aircraft, swimmers, or emergency service operations.
Communications and SITREPs
Before commencing the search, the Search Team should confirm:
- Search area,
- Start point,
- Track direction,
- Track spacing,
- Search speed,
- Radio channel,
- Call signs,
- SITREP frequency,
- Emergency process,
- What to do if the search object is located, and
- What to do if the task cannot be completed.
SITREPs should include:
- Current location,
- Search progress,
- Search legs completed,
- Areas covered,
- Conditions,
- Sightings or clues,
- Hazards,
- Resource status,
- Personnel fatigue or welfare concerns,
- Any change in capability, and
- Task completion.
Safety Considerations
Personnel conducting a parallel line search must maintain awareness of:
- Surf, swell, wind, tide, current, and drift,
- Other vessels or water users,
- Aircraft or RPAS activity,
- Reduced visibility,
- Sun glare,
- Fatigue,
- Communications limitations,
- Navigation errors,
- Collision risk,
- Search Team separation,
- Crew position and lookout effectiveness,
- Fuel or battery limitations,
- Access and egress, and
- Changes in environmental conditions.
Search activity must be managed using a risk versus gain approach.
SLS personnel must not continue a search task where conditions become unsafe or the task exceeds approved capability.
Locating the Search Object
If the person, vessel, craft, object, or clue is located, personnel should:
- Mark or record the location,
- Notify the SOC immediately,
- Provide a SITREP,
- Commence rescue or emergency care where safe and appropriate,
- Maintain observation if immediate rescue is not possible,
- Preserve potential evidence where required,
- Avoid disturbing the scene unless required to save life or prevent further harm, and
- Follow Control Agency or SLS command direction.
Completion of Search Area
When the assigned search area is complete, the Search Team should notify the SOC or coordinating role.
The update should include:
- Search area completed,
- Time commenced and completed,
- Search pattern used,
- Search tracks or route,
- Conditions during the search,
- Any areas not searched,
- Any sightings or clues,
- Hazards or limitations,
- Personnel or equipment issues, and
- Whether the Search Team is available for further tasking.
Records
Search activity should be recorded where practicable.
Records may include:
- Assigned search area,
- Start and finish times,
- Search tracks,
- GPS records,
- Search speed,
- Track spacing,
- Search Teams involved,
- Sightings or clues,
- Areas unable to be searched,
- SITREPs,
- Safety concerns,
- Task modifications, and
- Stand down instructions.
Records should be provided to the SOC for inclusion in the incident log.
References