Hand-Held Scanners for Personnel|
(Chapter 3 Metal Detection, Continued)
Procedures for the operator
While it is not difficult to learn to use a hand-held metal detector correctly, school administrators should not underestimate the value of annual training for their operators, as well as training for staff who may be called upon to serve as backup or supplemental operators. However, on-the-job practice is important in allowing the school to achieve the type of throughput that will be required in order to process students quickly.
Every school will want to tailor its own set of operator procedures to take into consideration its students' and community needs. Some generic procedures:
- The detector should be passed over the scannee's body at a distance of no more than 3 to 4 inches. Avoid touching the body or clothing with the detector. However, for some baggier clothing, such as pants or jackets, it may be necessary to hold the detector against or more into the fabric while scanning in order to stay within 3 to 4 inches of all body surfaces.
- Most hand-held metal detectors should be set at their highest sensitivity. An exception to this is if there is significant interference from metal reinforcing in a floor or other nearby material that could cause constant alarms unless the detector's sensitivity is turned down.
- The body scan should be performed each time in the same pattern so that the operator always knows what parts of the body still need scanning. A sample routine, illustrated in exhibit 3.10, follows:
- Ask the scannee to place all carried items, plus any caps or headgear on a table (procedures for manual search of baggage are not covered in this text). The scannee should stand with his or her feet about 18 inches apart, facing away from the table and about 2 feet in front of it. Footprints outlined on the floor or drawn on a mat can greatly help position the scannee properly. Ask the scannee to hold his or her arms out to the sides, parallel to the floor.
- Quickly run the hand-held detector across some piece of conductive material on your own body, such as a belt buckle. The ensuing squeal of the detector will assure you that the scanner is still operating properly.
- Start at the top of one shoulder of the scannee. With the paddle of the detector held horizontally and parallel to the front of the body, sweep down one side of the front of the torso, down the leg to the ankle, then move to the other ankle and sweep back up the front of this opposite leg and torso, ending with the opposite shoulder. (If a particular detector's detection paddle is less than half the width of the average body, or if a particular body is wider than twice the width of the detection paddle, the pattern will have to be modified to achieve adequate coverage.)
- Sweep the detector paddle over the outside top of the arm from the top of the shoulder to the bottom of the wrist, then up the inside of the arm to the armpit. Sweep down that side of the body to the ankle, then up the inside of that leg and down the inside of the opposite leg, then back up the other leg from the ankle to the underarm. Repeat the sweep of the inside and outside of this arm. Note that it would be particularly important to avoid touching the paddle up against the scannee's body when scanning up and down between the legs.
- Ask the scannee to turn around. (Arms can be put down now.) The pattern used to scan the front of the body should now be repeated over the back of the body.
- Ask the scannee to grab the edge of the table for support, then to lift one foot up in back of him- or herself. Scan across the bottom of the shoe. Repeat for the other foot. The operator should expect to hear a short squeal from the detector when scanning the bottom of shoes or boots with steel shanks or steel toes. Both shoes should cause equivalent squeals.
- For the head area, start at the top of the forehead and scan around the top of the head down to the back of the neck.
- Given that the type of hand-held detector being used is the kind that provides different volumes of feedback, i.e., a soft squeal versus a much louder squeal, the operator will be able to distinguish between the detection of a smaller innocuous item or material, such as a zipper, and the detection of a larger, more suspicious item. It is important to be attuned to these different volumes to recognize when further investigation is required for a particular scannee.
- When the detector identifies a suspicious item and there is no visible source for the alarm (clothing is shielding the source object), ask the person to show you what they have in that area. For example, for an alarm along the arm or wrist, have the scannee pull up his or her shirt sleeve. Using your detector, duplicate the squeal you heard before, but now over the visible item.
- Do not let the scannee influence you as to what is actually causing an alarm (exhibit 3.11). For instance, if the detector denotes the presence of a suspicious item under a shirt sleeve, do not fail to completely investigate the source of the alarm even though the scannee assures you that it is just his or her watch.
- If the person you are about to scan caused an alarm when walking through a portal metal detector, and your job is to try to locate the source of that alarm on his or her body, do not stop the complete scanning process just because you come across one alarm-causing item. Continue the scan even though you find one or more items in the process.
- The lower abdominal area is particularly difficult to scan because this area is private in nature and because of the metal items usually found in this area: belt buckles, metal buttons or snaps, and metal zippers. When doing the initial front body scan, if an alarm occurs in this area, there are two possible ways to further investigate:
- Ask the scannee to undo any belt he or she might have on and have him or her pull the belt ends away from the middle of the body. Now scan the zipper area; the feedback volume from your hand-held metal detector should tell you if it is now only sensing a zipper and/or a metal snap, or if a more suspicious item is present and further investigation is needed.
- A second approach that some schools use is that, if the lower abdominal area is causing an alarm on the hand-held detector, ask the scannee to bend the front of his or her front waistband forward, to ascertain that no weapon is hidden behind it. Facilities need to be available for situations where further investigation can be accomplished privately, but only in the presence of two or more school employees who are the same gender as the scannee.
Research Report: The Appropriate and Effective Use of Security Technologies in U.S. Schools