At first, both types of scanners showed travelers naked. The idea was that security workers could spot both metallic objects like guns as well as nonmetallic items such as plastic explosives. The scanners also showed every other detail of the passenger's body, too.
The TSA defended the scanners, saying the images couldn't be stored and were seen only by a security worker who didn't interact with the passenger. But the scans still raised privacy concerns. Congress ordered that the scanners either produce a more generic image or be removed by June.
On Thursday, Rapiscan, the maker of the X-ray, or backscatter, scanner, acknowledged that it wouldn't be able to meet the June deadline. The TSA said Friday that it ended its contract for the software with Rapiscan.
The agency's statement also said the remaining scanners would move travelers through more quickly, meaning faster lanes at the airport. Those scanners, made by L-3 Communications, used millimeter waves to make an image. The company was able to come up with software that no longer produced a naked image.
The TSA will remove all 174 backscatter scanners from the 30 airports where they are now in use. An additional 76 are in storage. It has 669 of the millimeter wave machines it is keeping, plus options for 60 more, TSA spokesman David Castelveter said.
Not all of the machines will be replaced. Castelveter said that some airports that now have backscatter scanners will go back to having metal detectors.
The Rapiscan scanners have been on their way out for months, in slow motion.
The government hadn't bought any since 2011. It quietly removed them from seven major airports in October, including New York's LaGuardia and Kennedy airports, Chicago's O'Hare, and Los Angeles International.