Search Effort

The Balancing Act Limited Resources Limited Resources Planning Time in Search Area – how much time does it take to complete a search assignment? Planning Time in Search Area – how much time does it take to complete a search assignment?

Time in Search Area Sample air search problem: Sample air search problem: –Quarter Grid (in Central Minnesota) –1 NM track spacing –90 Knots Airspeed

94 00’ W o 93 30’ W o 45 30’ N o 46 00’ N o 30’ x 30’

93 45’ o 94 00’ W o 93 30’ W o 45 30’ N o 46 00’ N o 45 45’ o 15’ x 15’

93 45’ o 94 00’ W o 93 30’ W o 45 30’ N o 46 00’ N o 45 45’ o Twin Cities

94 00’ W o 93 30’ W o 45 30’ N o 46 00’ N o 93 45’ o 45 45’ o ’ Twin Cities

94 00’ W o 93 30’ W o 45 30’ N o 46 00’ N o 93 45’ o 45 45’ o MSP 413 A B C D

94 00’ W o 93 30’ W o 45 30’ N o 46 00’ N o 93 45’ o 45 45’ o MSP 413 A B C D A

Computing Time in Search Area 1 “square” degree in Central Minnesota is about 60x42 NM, so a quarter grid is about 7.5 x 5.25 NM. Quarter Grid: MSP 413A 5.25 NM 7.5 NM

Computing Time in Search Area We have 8 sweeps 4.25 NM long each plus 7 NM distance covered moving between sweeps. That’s 8*4.25+7, or about 41 NM. At 90 Kts, that is about a half hour. Quarter Grid: MSP 413A 1/2 NM 1 NM 7.0 NM 4.25 NM

Time in Search Area Typical sortie assignment is a half grid (two quarter grids) Typical sortie assignment is a half grid (two quarter grids) Additional time is needed to travel to and from the search area Additional time is needed to travel to and from the search area For missions, we restrict our flight time in C-172s (with standard tanks) to three hours For missions, we restrict our flight time in C-172s (with standard tanks) to three hours

Search Time Equation A = V*S*T*N A = V*S*T*N –A, Area –V, Velocity –S, Spacing –T, Time –N, Number of Resources This equation works for ground search too (think search lines) This equation works for ground search too (think search lines)

Search Time Equation: Velocity, V Search Speed of SRU Search Speed of SRU –Not cruise speed For Aircraft, Kts For Aircraft, Kts For Ground Teams, MPH For Ground Teams, MPH –0.29 MPH typical »Based on studies of trained searchers in moderately dense trees and underbrush in the Pacific Northwest »works out to about 3.5 hours per mile

Search Time Equation: Time, T Time spent actively advancing the pattern Time spent actively advancing the pattern Time Enroute to and from search area not included Time Enroute to and from search area not included Must discount time spent maneuvering and investigating sightings Must discount time spent maneuvering and investigating sightings Rule of thumb for aircraft: Rule of thumb for aircraft: –T is 85% of time in search area –Less if complicated by lots of junk that needs to be investigated May be bound by available daylight hours May be bound by available daylight hours

Search Time Equation: Number of Resources, N Number of identical resources used Number of identical resources used Examples: Examples: –Number of searchers in a ground team –Number of aircraft searching at the same airspeed for the same length of time

Search Time Equation: Track Spacing, S The distance between searchers or legs of the search pattern The distance between searchers or legs of the search pattern

Search Time Equation: Solving for Other Variables Spacing Required Spacing RequiredS=A/(V*T*N) Resources Required Resources RequiredN=A/(V*S*T) Time Required Time RequiredT=A/(V*S*N) (We don’t generally try to solve for V)

Search Time Equation Recap Our Example One Last Time: A Quarter Grid in Central MN is 7.5 x 5.25 NM or about 40 NM 2 –T = A / ( V * S * N ) [from previous slide] –T = 40 NM 2 / ( 90 NM /hr * 1 NM * 1) –T = 4/9 hr  0.44 hr –But this doesn’t account for maneuvering (turning onto new legs of search pattern) »So, divide by 0.85, the rule of thumb, and we get 0.52 hr »This estimate assumes little time spent investigating sightings

The Balancing Act Revisited: The POA – POD Trade-Off Requirements for Successful Search: Requirements for Successful Search: –You must be searching where the person is »POA is the likelihood you are in the right place –You must be able to detect the person »POD is the likelihood you can detect the person Your goal: search an area large enough to likely contain the person but small enough so that your searchers will be closely enough spaced to likely detect the person Your goal: search an area large enough to likely contain the person but small enough so that your searchers will be closely enough spaced to likely detect the person An obvious conflict… An obvious conflict…