The full body scanner allows security agents to electronically peek under a person's clothes during the screening process. But the government is promising that procedures are in place to protect the privacy of air travelers.
This is not new technology. It has been tested at a number of airports for the last couple years, but it is moving now to the front lines for a number of reasons, most notably the Christmas Day bombing attempt with explosives sewn into the alleged bomber's underwear.
And, while the new machines still provoke debate over privacy, the TSA believes it has taken steps to mitigate that concern.
It's called a backscatter machine. You stand, raise your arms, and low-level x-ray beams take a full body picture. It is designed to detect items both metallic and non-metallic. In doing so, it also reveals your body in a chalk-like image that is reviewed in a room removed from the security line.
"The officer that is at the machine with the passenger does not see the image. The officer that's way over in the resolution room, who's look at the image, does not see the passenger," said Eddie Mayenschein, TSA general manager of security operations
The TSA says that as soon as a passenger's image is reviewed, and that person cleared to move to the gate, the backscatter image is deleted. The system, they say, does not allow for image storing or printing.
"You can see they strike a pose, and in just a few seconds the image is taken and is sent to the resolution room," said Mayeschein.
Unlike regular metal detectors, backscatter requires that you empty everything from your pockets, and you still must remove your shoes -- a practice that routinely tops the flying public's frustration list.
The whole business of advanced imaging technology has been in the testing phase for the last couple years, and while airport managers are watching, they don't believe it will slow the lines through security.
"Anything we can do to continue to layer our security process and add another measure of protection, I think, is appreciated by the general public," said Chicago Aviation Commissioner Rosemarie Andolino.
"If it's gonna help airport security, I don't see why not," said passenger Evan Puruleski of Detroit.
"I'd prefer not to, but if it's going to make everything safer, well I guess it's a better idea. I'm not sure it's necessary either. I think it's a bit hyped up," said Triona O'Dwyer, a passenger from Dublin, Ireland.
In theory, this type of technology would be able to detect non-metallic explosives sewn into someone's underpants, but there are limits. The x-ray image is skin deep. It doesn't see inside the body.
Twenty of these machines will be operational at O'Hare by this May as primary screening devices. Passengers do have the option of refusing to go through the backscatter, but they are then subject to a hand-wanding and pat down.
The one backscatter machine at O'Hare became operational Monday afternoon in United's Terminal One. It is the primary screening device in one security line. Passengers are not selected to go through it. For now, it is just luck of the draw. That, of course, will change when more machines arrive by May.