Search Planning Flashcards
Search planning is…
… the process where information is gathered and environmental considerations are used and evaluated to calculate where objects or persons, whose whereabouts are unknown, may be.
Includes how using relevant search assets, the probable area can be covered effectively using equipment and resources available.
CG Statement of Responsibility
Her Majesty’s Coastguard is responsible for the initiation and co-ordination of civil maritime search and rescue within the United Kingdom search and rescue region. This includes the mobilisation, organisation and tasking of adequate resources to respond to persons either in distress at sea, or to persons at risk of injury or death on the cliffs or shoreline of the United Kingdom.
Land search is an emergency because…
Missing person may only be responsive for a short period or require protection.
Better clues
Urgent response decreases search area and difficulty.
Urgent response allows more efficient search.
Information gathering process
Validation (is it reliable?)
Analysis (timeline)
Assessment (prioritise to develop FF)
Four types of clues
Physical
Recorded
People
Event (including triggers)
Two information gathering form types
Lost person details form
Search Urgency Assessment
Parts of the reflex model
Axel Hub Rim Spokes Reflectors
The axel is..
Last known point
IPP
The hub is…
Approx 300-500m initial search area.
The rim is…
The max probable distance the misper travelled.
The spokes are…
Likely travel routes
Path of least resistance
Reflectors are…
Points of interest or hazards
Three levels of search
Hasty
Efficient
Thorough
Casualty search info (6)
Last known position Course & Speed DSP Object Intentions LSA
SRU search info (4)
Equipment
O/S arrival time
O/S endurance
Hazards
Environmental search info (6)
Wind Tide SR/SS Twilight Sea state Visibility
Leeway is…
downwind drift, proportionate to force and dependent on the objects profile.
Two types of datum search pattern
Expanding square
Sector
Characteristics of expanding square
Surface vessels impacted by drift
Stopwatch and compass used
Sector search…
Requires a datum object
High coverage in small area
Seven types of area search pattern
Parallel track Creeping line Track line Estuary Barrier Shoreline Multiunit parallel
Parallel track is…
ground based
able to be added directly to RNLI plotters
longest leg parallel with longest side
Creeping line is…
longest leg parallel with shortest side
Track line search is…
best for quicker assets
tedious
common in a track line return
Shoreline search is…
a modified parallel track using the contours of the shore. Radar can be used to maintain distance.
Sweep width definition
Uncorrected sweep width x correction factors
Coverage factor definition
Corrected sweep width / track spacing
POD definition
likelihood that an SRU will see the object given the…
Correction factors for sweep width
Object size Detection aids Sea state Wind speed Aircraft altitude & speed Fatigue
AVNST
Area Velocity Number Spacing Time (beware datum time)
TAPSIC
Target Area Pattern Search details Information Communication
T
Target - type, description, detection aids
A
Area - circular, corner or boundary method or trackline search
P
Pattern - expanding square etc
S
Search details - CSP, leg length etc
I
Information - Weather, OSC, other SRUs
C
Communications - channels, safety checks
Divergence is…
caused by the wind in relation to exposed and underwater surfaces of the object, causing it to diverge from the downwind track. The angle either side of a mean drift that objects fall between. Dmin & Dmax
Search Area Evaluation…
… describes the area to be searched. Used within IAMSAR. It is the process of generating the search area.
SAE for datum area - no divergence
Plot DSP Plot tidal vector Plot leeway = Datum point Plot error radius Box off and label
SAE for datum area with divergence
Same to datum point
Plot divergence from the end of TIDAL VECTOR
Plot error radii
Box off and label
Rapid response model
used for short elapsed time and/or when environmental factors are minimal - commonly up to one hour
Other methods of search
Datum line Back track Flare RRS EISEC data
Types of error
Fix accuracy
DR error
Environmental - 30% of drift vector
Relationship between DET and DR error
DET up
DR error down
Datum line key points
Based on previous track of vessel or MOB Plot DSPs along line DSTs will be different DET up = DR error down Create datum area for each DSP
Back track key points
Calculates search area from found object Model drift of object back to 3 locations using reverse leeway and divergence Apply errors Apply leeway and divergence forward Use best possible estimate for DST
Flare model key points
Plot FIF location and line to max detection range
DSP along the line. DST THE SAME FOR ALL.
Apply leeway and divergence
Apply errors
RRS key points
Height of aerial known
Height of vessel aerial assumed
Nominal range = 2.21 x sq rt antenna height (m)
Add the two ranges to get transmission range
DSPs along edges of overlapping area
EISEC sector
via Tactical Commander & SPOC
DSPs along edges of 120 deg sector
EISEC centroid azimuth
DSP at centroid centre, plot tide, leeway and divergence. Radius of centroid is the error.
SAD stages
Preliminary evaluation Choose model type DST, DSP and errors Search duration Datum time DET Estimate drift and errors Establish probable locations and define area
DST
Drift start time. The time when the casualty is known, or estimated, to have first started to drift.
DSP
Drift start position. The position the casualty is known, or estimated, to have first started to drift. May be the LKP or a position from DR from a previous fix.
IPe
Initial position error. Includes navigational fix error and DR error.
FIXe
Navigational fix error. Accuracy of the last known fixed position. See navigational fix error tables in SAD tables.
DRe
DR error. See DR error tables in SAD tables.
Search duration
How long the search is going to take. Consider: Fatigue Number of searchers Survival times Time of day On-scene endurance
Datum position
The most probable location of the casualty at any given time. May be a single point, a set of points, a line, arc or area.
Datum time
The time for which the search area is valid. For RR will be the time of arrival at datum position of the SRU.
DET
Drift elapsed time. The period of time over which the target is drifting - from DST to datum time.
Resultant drift vector
DSP to datum. Resultant vector of the tidal vector and leeway vector.
De
Drift error. Uncertainty in leeway and tide. 30% of the total drift distance.
Total error radius
IPe + De
