WASHINGTON — High-tech security scanners that might have prevented the Christmas Day attempt to blow up a jetliner have been installed in only a small number of airports around the world, largely because of concerns over the way the machines see through clothing.
The technology is in place at 19 U.S. airports, while European officials have generally limited it to test runs.
Umar Farouk Abdulmutallab, the Nigerian man accused of trying to ignite explosives aboard a Northwest Airlines jet as it was coming in for a landing in Detroit, did not go through such a scan where his flight began, at Amsterdam's Schiphol airport.
The full-body scanner "could have been helpful in this case, absolutely," said Evert van Zwol, head of the Dutch Pilots Association.
But the technology has raised significant concerns among privacy watchdogs because it can show the body's contours with embarrassing clarity. Those fears have slowed the machines' introduction.
Jay Stanley, public education director for the American Civil Liberties Union's Technology and Liberty Program, said the machines essentially perform "virtual strip searches that see through your clothing and reveal the size and shape of your body."
The U.S. Transportation Security Administration, part of the Department of Homeland Security, has begun installing two types of advanced scanning machines.
These machines, which cost six figures each, screen airline passengers without physical contact. They can reveal plastic or chemical explosives and non-metallic weapons.
TSA has deployed 40 "millimeter wave" machines, which use radio waves to produce a three-dimensional image based on energy reflected from the body.
Six of those machines are being used for what TSA calls "primary screenings" at six U.S. airports: Albuquerque, N.M.; Las Vegas; Miami; San Francisco; Salt Lake City; and Tulsa, Okla.
This means passengers go through the scans instead of a metal detector, although they can elect to receive a pat-down search from a security officer instead.
The remainder of the machines are being used at 13 U.S. airports for secondary screening of passengers who set off a metal detector: Atlanta; Baltimore/Washington; Denver; Dallas/Fort Worth; Indianapolis; Jacksonville and Tampa, Fla.; Los Angeles; Phoenix; Raleigh-Durham, N.C.; Richmond, Va.; Ronald Reagan Washington National; and Detroit. Travelers can opt for a pat-down instead in those instances as well.
The agency also has announced plans to buy 150 "backscatter" machines, which use low-level X-rays to create a two-dimensional image of the body, from Rapiscan Systems, a unit of OSI Systems Inc. Those machines, which cost $190,000 each, are being deployed in U.S. airports now.
"The machine gives a very accurate and very precise image of things on the body that are not the body," said Peter Kant, executive vice president of global government affairs for Rapiscan.
Last June, however, because of privacy concerns, the House voted 310-118 to prohibit the use of whole-body imaging for primary screening. The measure, still pending in the Senate, would limit the use of the devices to secondary screening.
"As a society, we're going to have to figure out the balance between personal privacy and the need to secure an aircraft," said Rep. Jason Chaffetz, R-Utah, who sponsored the measure. "And there is no easy answer."
Executives at the companies that make the machines insist there are ways to strike that balance.
Kant said the technology has evolved enough to produce body images that look like chalk outlines. In addition, privacy filters can blur faces, noted Colin McSeveny, communications manager for Smiths Detection, a British company that makes millimeter wave machines that are being tested in Europe and the U.S.
TSA said it safeguards privacy by ensuring that all full-body images are viewed in a walled-off location not visible to the public. In addition, the security officer assisting the passenger cannot view the image and the officer who views the image never sees the passenger. Also, the machines cannot store, print or transmit any images they produce.