The TSA accelerated its use of advanced scanners in 2010 following the failed Dec. 25, 2009, attempt by Umar Farouk Abdulmutallab to blow up a Northwest Airlines flight by igniting explosives in his underwear.
L-3 scanning machines rely on millimeter-wave technology, which uses radio frequencies that can find both metallic and non-metallic items. Rapiscan's machines are based on backscatter technology, which uses low-dose X-ray radiation to detect objects under a passenger's clothes.
Airline passengers were offended by the revealing images, including those of children and the elderly. The Washington- based Electronic Privacy Information Center sued the agency in July 2010 claiming the scanners violated privacy laws and has called use of the machines equivalent to a "physically invasive strip search."
Under pressure from privacy advocates and some members of Congress, the TSA moved its screens to separate rooms away from airport security checkpoints. Officials monitoring the scanner images alert agents if they see a possible risk.
The agency put out a contract in August 2010 asking L-3 and Rapiscan to develop the software to make images less revealing. L-3 developed its product in 2011, according to John Sanders, the TSA's assistant administrator for security capabilities.
Rapiscan recently indicated to agency officials that it couldn't deliver its software until 2014, Sanders said. It couldn't come up with an algorithm that met the agency's standards for accurately detecting objects without generating false alarms, he said.
"You can have a high probability of detection but a great deal of alarm," Sanders said. "Everybody's alarming. That doesn't work from an operational perspective."
TSA has contracted with L-3, Smiths Group and American Science & Engineering Inc. for new body-image scanners, all of which must have privacy software. L-3 and Smiths used millimeter-wave technology. American Science uses backscatter.