ׁ WARNING. The construction and layout of IEDs often means that a searcher may only detect one component or one material inside a larger component. An example of this is a carbon rod in a low metal content pressure plate. This must be factored into how detectors and follow-on excavation drills are conducted.
Metal detector checking for metal anomalies in an earthen walled structure
Image 7. Some buildings only contain limited metal in the structure yet metal detectors may still provide benefit to search operations
3.4.2. FALSE POSITIVES False positives in detector search has been an issue in wider MA operations since their conception in the late 1980s. An example of this is data gathered by the Cambodian Mine Action Centre, from March 1992 to October 1998, that shows that for every item detected there was a 99.7 percent chance that it was scrap metal and not EO. This figure would certainly hold true in urban areas, where metal contamination exists in large quantities alongside EO contamination. Detector search procedures should consider in detail the degree to which false positives will reduce efficiency and these should be mitigated as far as possible. Procedures should consider gross contamination to the point where detectors are not able to provide any value to the searcher. This should be linked with the MA organisation’s accredited SOPs to state under which conditions rapid excavations could be conducted or certain signals not investigated at all. The type of detector being used in relation to the IED threat will significantly influence these SOPs.
Search core skills and procedures
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