ATLANTIC CITY, N.J. — On Dec. 22, 2001, passengers on a flight from Paris to Miami subdued Richard Reid after he attempted to bring down the airplane with a high-top sneaker filled with explosives.
Ever since, travelers at airport checkpoints have been asked to take off their shoes and send them through x-ray machines.
Since the 9/11 hijackings, passengers have submitted to a variety of new Transportation Security Administration procedures, and some may have walked through the portals of a few new screening machines. However, the basic technology — metal detectors for the passengers and x-rays for the hand-carried baggage, has remained the same.
The relatively new TSA, meanwhile, has attempted to deploy cutting-edge sensors designed to both increase security and make the procedure smoother for passengers. Its efforts have been marked by notable failures, and few new technologies deployed uniformly throughout the United States. The problem of finding explosives concealed under clothing has not been completely solved.
“One of the hard lessons we’ve learned is that there is no single technology that is going to detect everything,” Clark Kent Ervin, former DHS inspector general and now director of the Aspen Institute’s homeland security program, said in an interview.
The United States is capable of developing the technologies needed to both boost security, and make the passenger screening procedure go faster, it just hasn’t done so yet, Ervin said.
“Terrorists are on a quick timeline and we have got to be quick,” he said. “We are capable of doing these kinds of things.”
After 9/11, changes in TSA procedures have come in reaction to terrorist plots to detonate bombs aboard passenger aircraft. The actions of Reid, better known as the “shoe bomber,” resulted in the footwear rule. A London-based plan to take down 10 aircraft in 2006 necessitated the banning of large quantities of liquids in hand-carried luggage. The so-called Christmas Day plot, which had Umar Farouk Abdulmutallab allegedly concealing plastic explosives in his underwear, prompted the TSA to dramatically boost the numbers of its new advanced imaging technology machines.
Abdulmutallab’s attempt to destroy a Detroit-bound airliner highlighted the biggest vulnerability in passenger screening — the ability to detect explosives carefully hidden underneath clothing.
Scientists and engineers at the TSA Security Laboratory near the Atlantic City airport are conducting basic research on promising technologies, although many of them are several years away from being deployed, if they ever do bear fruit.
“We have people who have spent their whole professional careers here worrying about how to find a bomb,” said Susan Hallowell, the lab’s director.
Potential screening technologies are put through rigorous testing procedures. The lab has an extensive “library” of real explosives, military grade, or homemade, that it stores in a bunker on site, as well as experts whose job is to construct concealed bombs designed to trip up the machines. (
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“Everybody wants to get the technology in the field because it’s needed,” Hallowell said. “But if it’s not effective for one reason or another, it breaks down, it’s not usable or there is some other defect, it’s not of value.”
Once the lab gives a new scanning machine the stamp of approval, it is turned over to the TSA for field tests in airports.
“Sometimes you see things that work well in a laboratory, but when you take them to an airport, operationally, they fall down,” Hallowell said.
The most glaring example of this was the “puffer” machines.
Beginning in 2004, TSA began to install in some airports portals that shot jets of air over passengers, which would then dislodge trace amounts of explosives from their clothes and bodies. These picogram-sized traces were sucked into a collector that would alert a TSA officer of their presence.
The machines, which ultimately cost taxpayers some $36 million to deploy, began to malfunction as the sensors became clogged with other particles. They also had a high rate of false positives. Jet fuel fumes, for example, set them off, according to Government Accountability Office reports.
Hallowell said the puffer machines were sped into the field prematurely in reaction to the so-called “black widow” bombings in Russia in 2004, when it was believed that Chechen women carrying explosives underneath their clothes made it through Russian checkpoint security and blew up two aircraft. Traces of the military grade hexogen explosives were found on both flights.
TSA was a relatively new agency then, and Hallowell said there was a collective decision to deploy the machines.
“They went to the field too fast and we didn’t have a chance to really kick the tires and make sure it was operationally very effective,” she said. It was a “lesson learned,” and there are now processes in place to ensure the mistake isn’t repeated, she added.
The TSA, in the meantime, will rely on three technologies to prevent concealed bombs from making it on to airplanes. The first are the controversial advanced imaging technology sensors that peer underneath clothing to look for shapes that may be explosives or other contraband. There are two kinds of AIT machines, one that uses millimeter waves, and another that uses backscatter radiation.
AIT machines were being slowly rolled out at airports throughout the country last year despite being criticized by privacy advocates for creating images that revealed subjects’ bodies.
In the wake of the Christmas Day plot, DHS announced the widespread deployment of the machines. Plans now call for the agency to boost AIT numbers from 878 to 1,800 and to make them a third primary screening technology along with the standard metal detectors and carry-on baggage x-ray machines. The goal is to have them in every U.S. airport by 2014.
The Government Accountability Office in a March report warned that the rapid deployment of AIT harkened back to the puffer machines. They too were an example of a technology that was rushed into airports in response to an attack. TSA responded that backscatter x-ray and millimeter wave sensors were further along in the development phase than the puffer machines when they were deployed, and that AIT had been rigorously tested in operational settings.
Ervin said he is not worried about the privacy concerns with AIT technology. DHS said the machines automatically delete the body imagery as soon as a passenger clears the checkpoint. And the TSA officer looking at the data is in another room and cannot see the subject’s identity.
“I’m concerned that they are putting so many of their eggs in the basket as far as AIT,” Ervin said. “What we have found is that there is no silver bullet technology out there and you have to have a variety,” he said.
AIT machines can only sense shapes. The GAO report said it was unclear whether the technology could have detected the explosives in Abdulmutallab’s underwear.
Hallowell said the “fairly traditional military explosive” used in the plot was well known, and in the lab’s inventory.
“I think the interesting part of that scenario was the attempt to make an artful concealment,” she said.
To find carefully hidden explosives, TSA has placed at least one trace explosives detector in every U.S. airport. Like the puffer machines, these devices search for the chemical signatures of explosives. However, they require agents to swab a passengers’ hand or luggage, which is a labor-intensive procedure, and slows down the screening process. Because of the time-consuming nature of the technology, TSA is only carrying out this procedure randomly.
During a tour of the Transportation Security Laboratory, scientists demonstrated several potential solutions for ferreting out concealed explosives. There is a sensor in the works using terahertz waves that could potentially peer underneath a passenger’s clothing and read the chemical signature of objects hidden there — a combination of the AIT and trace detector’s capabilities. Another machine can read the fumes coming off a bottle of liquid to determine if it contains the chemicals needed to mix explosives. These experiments are still being done on lab tabletops and could be years away from being used in airports, Hallowell cautioned.
TSA officials said there are currently no plans to revive puffer machine-like technologies that would allow passengers to walk through a portal and be tested for traces of explosives in a quick, non-intrusive manner. For now, it will be a combination of AIT machines, which are at least four years away from being deployed in all U.S. airports, and random swabbing.
Meanwhile, what about the shoes? Will there ever be a day when passengers don’t have to walk through checkpoints while wearing their socks?
TSA is making a renewed effort to remedy this, said Domenic Bianchini, general manager of the TSA’s passenger screening program. The agency recently completed an “extensive” market survey to determine what kind of technologies and sensors are currently available. A broad agency announcement has been released seeking proposals.
He wouldn’t give a deadline or timeline for when a shoe scanner might reach airports. “But we are very serious about it. We need to understand what’s possible, and will this technology meet our requirements at the end of the day.”
Hallowell said there have been efforts to solve the shoe problem in the past. The lab has looked at a variety of technologies, everything from trace explosive detectors to scanners that can peer into the shoe. Nothing was deemed “ready for prime time,” she said.
Both Hallowell and Bianchini said a solution to the problem will probably require integrating it with a currently deployed machine. The metal detector is at present the only portal that every passenger must pass through, so that is one obvious candidate.
“We have seen some partial solutions that aren’t fast enough and the last thing we want to do is put another thing in the airport that will … slow down the queue or require another officer to operate,” she said.
That’s why the integrated approach is necessary, she added.
“I think the game is to make sure that the whole security suite addresses all your threats. The sense now is that shoe scanners will be part of a larger suite, and that’s how we’re going to end up using it,” she said.