LarryJ, I think what Wally Bird meant when he said "rationale" was "stated reason", which is not always the same as the "actual reason." In other words, I think he meant that AIT was put into place for reasons other than those stated by TSA.

de·tect/diˈtekt/
Verb: Discover or identify the presence or existence of.

Nope, AIT cannot do that with explosives. Or pretty much anything else, either, at least not reliably or consistently.

There are two types of AIT - those with ATR and those without.

Those without ATR detect absolutely nothing - NOTHING. They merely create a digital image which is viewed by a human operator, and the human operator examines the image in an attempt to identify prohibited items on the image's subject. This is fraught with flaws, not the least of which being the fact that the operator might be asleep at the wheel, or might be a genuine perv who sends cutie pies or little children through the scan multiple times to get his jollies while ignoring his assigned task of looking for WEI. But be that as it may, non-ATR AIT doesn't actually "detect" a damn thing, any more than my phone's camera "detects" anything when I take a picture with it. It merely creates an image; any detection of anything is done with my own eyes, by examining the image.

AIT with ATR, on the other hand, doesn't create an image. Rather, it runs the scan returns through a software analysis, which is supposed to "detect" prohibited items by identifying "anomalies", i.e. "stuff which does not match the scan return properties of human skin." But this software, and the rationale behind it, is severely flawed.

You see, almost any object in the universe other than human skin fits the profile of "stuff which does not match the scan return properties of human skin," so the scan is basically looking for "the whole universe except human skin." But the whole universe does not consist of prohibited items, so even when the software identifies a scan return that doesn't match human skin, it hasn't really discovered or identified anything; it's up to the human operators to discover and identify the object which made the non-skin scan return - almost all of which are NOT prohibited items, such as folds of cloth, rolls of fat, or human sweat, which thus qualify as false alarms or false positives.

eas·y/ˈēzē/
Adjective: Achieved without great effort; presenting few difficulties.

Okay, how is this for easy - two guys get jobs, one at the Burger King in Concourse A-B at BWI, the other for the food service delivery company that supplies Burger King with its consumables. Delivery guy stops his truck at a truck stop or WalMart parking lot on the way to BWI and hides prohibited items inside the boxes of frozen burgers, trays of buns, or bags of Coke syrup. Burger King guy then retrieves the prohibited items when the supplies are delivered and hides them within the sterile area.

Bingo. Easy.