As US lawmakers demand to know how a would-be attacker smuggled explosives aboard a plane on Christmas Day, the use of body scanners at airport security points is likely to be revisited.
The machines are considered effective and have been tested at numerous international airports, but they are also controversial because they scan beneath clothing to detect items that may be hidden from ordinary view.
Security experts believe that the scanners could have detected the explosives that Umar Farouk Abdulmutallab was hiding as he boarded a Northwest Airlines plane in Amsterdam last week.
Abdulmutallab attempted to bring down the Airbus 330 by combining a flammable liquid he was carrying in a syringe with an explosive powder known as pentaerythritol (PETN) that was sewn into his underwear.
The metal detectors that passengers ordinarily step through as their luggage is being X-rayed would not have detected either component, experts said.
In the wake of the failed attack, British Interior Minister Alan Johnson said on Monday he would consider installing full body scanners at British airports “as quickly as possible.”
In the US, the scanners are already used at 19 airports and a handful of courthouses and prisons, the US Transportation Security Administration says.
The machines look like small booths and use radio frequencies to scan underneath clothing and produce a 3D image of the individual’s body.
While the scanner does not produce an image of the naked body, it has caused consternation among privacy advocates because it does faithfully reproduce individual curves hidden beneath clothing, from the shape of a breast to a roll of fat.
The device has been tested in numerous European airports, but its use was halted after the EU expressed concerns and protested a plan to install the scanners at airports throughout the EU.
EU representative Martine Roure praised the mothballing of the project, saying it would have been “disproportionate to submit all passengers to this type of check in the name of the fight against terrorism.”
But Thursday’s failed attack could prompt lawmakers worldwide to change their minds about the body scanners.
Successful and failed terror attacks targeting airplanes have already led to significant changes to the way people fly.
After the Sept. 11, 2001, attacks, pilots began locking the cockpit door behind them to prevent hijackers from accessing the flight controls.
In the wake of Richard Reid’s failed December 2001 attempt to detonate explosives in his shoes, passengers now routinely submit their footwear to inspection before boarding a plane.
And after authorities uncovered a plot in 2006 to blow up airliners with explosives in liquid containers, new regulations were imposed limiting the amount of fluid each traveler could bring aboard a flight.
Bruce Hoffman, a terrorism expert at Georgetown University, told reporters that traditional security measures simply would not be able to detect the sort of explosive Abdulmutallab was carrying.
“There is no other way, except for a body scan, to detect it,” he said.
Even the secondary screening measures sometimes used at airports would have failed, he said.
“If [if the explosive PETN] was sealed extremely tight in plastic, dogs wouldn’t have picked it up,” he said.
Douglas Laird, a former security director for Northwest Airlines, agreed, noting it was virtually impossible to know what was beneath clothing without the scanners.