Several private security experts also spoke about the necessity of such machines.
"The TSA, to me, gives credible assurances that that isn't going to happen," said Cathal "Irish" Flynn, a former FAA associate administrator for security who now runs his own consulting firm. "Could there be mistakes? Yes, I suppose so. But as I listen to them, they seem determined not to let that happen."
John DiScala, a blogger known as Johnny Jet, said the TSA should take note of this release and be careful.
"They need to realize if this was them, heads would roll. They need to do everything in their power -- and I mean everything -- to prevent this from happening," DiScala said. "There's already a grassroots effort to ban these machines when just a year ago almost everybody wanted them. It just shows how many people are comfortable with their bodies or being touched. It's a real fine line and they've only got one shot at this."
The full-body scanners, formally known as Advanced Imaging Technology, provide security screeners with what are essentially nude images of travelers. To ensure privacy, the TSA says, faces are blurred and the images are deleted once the TSA officer determines that the passenger is not a threat. The person viewing the images is in a remote location and communicates with the on-site officer via radio.
Passengers worried that their nude photos may end up on the Internet (or concerned about the radiation from the scanners) can opt to bypass the machines. But those travelers then must undergo a more-intrusive search, including the new patdown procedure in which a same-gender TSA agent touches the inside of passengers' inner thighs and women's breasts.
That new patdown alone has generated controversy as passengers, and even some pilots, have equated it with sexual assault. Pilot unions started to advise their members to have the patdown done in private.
Then, over the weekend, a 31-year-old software programmer was thrown out of San Diego International Airport after he got into an argument with a TSA screener about the new, more aggressive patdown.
"If you touch my junk, I'm going to have you arrested," John Tyner told the male screener. Tyner recorded audio of the whole 30-minute incident with the TSA on his cell phone's video camera, a video that has now had hundreds of thousands of hits on YouTube and been replayed on major television stations.
Despite the controversy, security experts say such searches are necessary to protect travelers.
"The patdown is unavoidably intrusive, embarrassing, uncomfortable, but it's an unfortunate price of security these days to keep the components of bombs off planes," Flynn said. "It's a dangerous world, and the probability of an attack on flights on any given day are extremely low, but the results of one such attack by the terrorists can be of course catastrophic."
"The patdowns in my option are necessary," said Jim Welna, who served as the chief of police at the Minneapolis-St. Paul airport for 17 years and spent four years working for the TSA. "It's a very thorough search, but there isn't an alternative to it given how the current system works. The current system treats everybody as an equal threat."