But user screening, awareness, behavior and education are now paramount.

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Security personnel should be given wide discretion to use the machines for anybody with suspect behavior or whenever there is a need for secondary screening.

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If a passenger sets off the metal detector, engages in suspicious behavior, or is listed on a watch list, secondary screening would be appropriate.

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"You can have perfectly effective screening processes and admissions processes and not in any way be able to predict behavior a decade forward, " she said.

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Right now the FAA and airlines rely on random screening and computer-assisted passenger screening to decide which bags should be screened, based on a profile of suspicious behavior.

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