Metal Detectors have been around for a long time. They can accurately detect metal objects, such as guns and knives, and do a pretty good job of it. The hand held versions do a great job in finding metal objects on the beach and hobbyists young and old can enjoy weekends searching for buried treasure.
As a personnel screening device, however, better and more practical technologies exist.
Metal detectors do not, as the name suggests, necessarily detect metal. They actually recognize any material that conducts electricity. Most think that the larger the object, the easier it is for the metal detector to find it. Not true. The size or shape of the object is immaterial to the detector. Herein lies one of their several weaknesses: The machines will detect anything from a harmless hair clip to a full-size AK47. They also don’t catch everything and can be defeated.
As most everyone knows by now, being screened by a metal detector at the airport or at some secure facility can be a long and arduous process necessitating removal of just about everything on your person. Airports require shoe removal, interestingly, because the average metal detector cannot detect metal in the shoes. I will explain why in a moment.
Metal detectors function by generating an electromagnetic pulse that produces a small electric current in an object that conducts electric current. If the pulse causes an object to produce the electric current, the receiving mechanism of the metal detector lights up or buzzes alerting the operator.
This technology has many weaknesses. To use them effectively they must be calibrated to zero out the effects of nearby metal or conductive objects. Rebar in walls, metal desks, chairs, wires, etc. all can affect the operation of a metal detector. There are some locations where they simply will not work. Companies must train guards or operators in calibration. The machines must be recalibrated every time they are moved or jarred. Most manufacturers charge extra for the calibration machines.
Metal detectors can often be defeated. You probably are familiar with being told to stop before entering the screening portal, then told to walk at a normal pace through the portal without stopping. If you stop and moon walk through the archway slowly, oftentimes the metal detector cannot detect any conductive object on your person. By moving slowly you can fool the detector. Operators must be trained to ensure that people enter and exit the portal properly to ensure detection of threat objects.
This “dance” each person performs limits the throughput to, at best, 200-300 per hour per machine.
Most metal detector operators require you to remove your shoes due to the field generating limitations and calibration. The electromagnetic pulse does not reach down exactly to floor level due to calibration and other issues. A razor blade, for example, in your heel may not be detected.
Other technologies available do a much better job at discriminating threat objects from harmless ones. They also have quicker through put and do not require calibration.
Metal detectors have their uses. They do what they do very well. For some uses, this is more important than the limitations. The Secret Service, for example, uses metal detectors in many cases despite a robust budget that allows them afford many other, more efficient, technologies. They may use other technologies too, but they use metal detectors on high threat details, for example, when they want to detect everything. They do not want any object to slip by them.
Sometimes older tech, like my reliable .45 caliber M1911 pistol, can still do the job despite limitations.
Disclaimer: The content in this article is the opinion of the writer and does not necessarily reflect the policies or opinions of US Patriot Tactical.
As Vice President of a Security Fusion Center, Bill has provided risk management advice and direction to major Fortune 100 defense industry, ultra high net worth and other clients.
As Global Director for Security, Alem International, Bill planned and directed all facets of the security and risk mitigation strategies for the 2004 Olympic Torch Relay that took place in over 34 countries.
Bill was commissioned as an Explosive Ordnance Disposal (EOD) Officer in the US Army immediately after college.
Mr. Gaskill has a Bachelor of Science degree in Ancient History with a math minor from the University of Wisconsin-Madison.He has a current Top Secret/SCI clearance.He has professional fluency ratings in Spanish, Greek, Hebrew and French, and has a working knowledge of Russian.