*** Prioritizing Multiple SAR Resource Deployments *** *** to the Same Search Area *** From: Martin Colwell sar_admin@mindlink.bc.ca 12th May 1996 From the Emergency Response Institutes 'Search is an Emergency' manual: 'Keep in mind that some segments have more than one resource committed to that area. The POA stays the same [at that point in time] while the %POD changes with the resource.' Obviously this point cannot be stressed often enough. Regarding the question about how to prioritize different combined resources searching the same area and the effect of their cumulative POD: The example given in the ERI text only examines different single-resource options for each area i.e. prioritize this resource OR that resource. This was to get people used to the Search Priority concept and to illustrate the great effect that faster resources or higher POD's have on raising the search priority value. Now to the question - How do we prioritize deploying multiple resources, i.e. this resource AND that resource to the same search area, and, just as importantly, in what sequence do we deploy these combined resources? To do this I believe that we have to consider these different resources as a total deployment entity, i.e. to work with the total (cumulative) POD of the combined resouces, to factor in the total search effort (manhours) that these different resouces will need to apply to reach their cumulative POD and to take into consideration how the POA will shift after each one of these resources has been deployed to the search area. This last point is critical as the sequence of deployment has a profound effect on the POA for the next resource and hence on the search priority. It seems to me that we have to calculate these four steps in turn: 1. Calculate the cumulative POD for all the combined resources to be deployed to the search area. 2. Sum the total search effort of all of these combined resources i.e. sum (No. of Searchers x (Access hours + Exit hours + Search hours)) for each resource to be deployed to reach their cumulative POD in that search area. (This is because to reach the combined cumulative POD will require the summed expenditure of all these resources search efforts). 3. Shift the area's POA after EACH combined resource has been deployed to its predicted POD. (Obviously the area's POA will shift after each resource has searched the area). 4. Use the shifted POA as the new POA for calculating the correct search priority value for the combined resources. (for that sequence of deploying multiple resource within that search area). It is important to remember that the sequence of deploying these combined resources to a single search area can have a profound effect on that area's search priority. This 4-step procedure can be used to select the most effective deployment sequence from a list of alternative deployment sequences. Let us use the Monti(zambert) Cr. area of the ERI example as our assignment. It has an intial 5%POA. The remaining eight areas cover 83%POA + 12%ROW We may wish to consider four search options for the Montizambert Creek area: Option 1: A 20%POD helicopter alone Option 2: An 80%POD 3-man team alone Option 3: A 20%POD helicopter followed by an 80%POD 3-man team (84%cumPOD) Option 4: An 80%POD 3-man team followed by a 20%POD helicopter (84%cumPOD) Calculating search priority using the four steps listed above produces the following search priority ranking: Initial Shifted Acccess+ No. of Total (POA x cPOD) Search POA POA exit+search Searchers search /searcher Priority hours -hours -hours Ranking Option 1: (0.05x20/0.44) 20%POD 5% - 0.22 2 0.44 = 2.273 #1 helicopter Option 2: (0.05x80/20.25) 80%POD 5% - 6.75 3 20.25 = 0.198 #2 3-man team Option 3: 20%POD helicopter 5% 0.22 2 0.44 then 80%POD 3-man team 6.75 3 + 20.25 (0.04x84/20.69) ----------------- ------- cumulative POD=84% 4%shifted POA (20.69) = 0.162 #3 (after 20%POD helicopter search) Option 4: 80%POD 3-man team 5% 6.75 3 20.25 then 80%POD helicopter 0.22 2 + 0.44 (0.01x84/20.69) ----------------- ------ cumulative POD=84% 1%shifted POA (20.69) = 0.0406 #4 (after80%POD 3-man team search) This example illustrates some important points: Option 1, applying the helicopter alone provides the highest search priority as very little effort (manhours) is required to reach 20%POD. Option 2, reaching 80%POD using a 3-man team has the next highest priority, although its priority value is less than one tenth of the helicopter alone, primarily because of the much greater manhours required by the ground team to reach 80%POD. Option 3, deploying the 20%POD helicopter followed by the 80%POD 3-man team has only a slightly lower priority value than option 2, because only marginally more manpower is required by the helicopter to raise the cumulative POD from 80% to 84%, while not substantially reducing the areas POA (from 5% down to 4%). Option 4, deploying the 80%POD 3-man team followed by the 20%POD helicopter has a significantly lower priority value (one quarter) than option 3, because the 3-man team would have already searched the area to 80%POD, thus reducing the area's POA down from approximately 5% to 1%. The search priority of this deployment sequence is reduced by a factor of four because of the low benefit of searching the now low, (1%)POA area, by helicopter to only raise the POD from 80% to 84%. Clearly this is the least attractive of the four search options. This four-step approach can be used to determining the optimum sequence for deploying multiple resources to the same search area. This could be of great value when a large number of resources have to be deployed to a number of search areas, although it does require performing both search priority and shifting POA calculations. copyright Martin Colwell 1996 -----------------------------