Jan. 17--WARWICK -- Since 2004, security officials at T.F. Green Airport have tried to spot dangerous passengers by a pulsing cartoid artery, how much they sweat, blink, and behave in ways that might indicate an anxiety that stems from something more sinister than a fear of flying.
The federal Transportation Security Administration is looking for passengers who have their stress hormones up and running because they intend to attack the air transportation system.
Green was among the first three airports in the nation to test "behavior detection techniques" -- a list of "tells" that federal officials think may help them to identify terrorists.
Joseph S. Salter, the federal security director assigned to Green, said "a significant number" of TSA's 250 officers at Green have been trained in the program officially known as "Screening Passengers by Observational Techniques," or SPOT.
So have members of the Rhode Island Airport Police Department, the state employees that TSA calls upon to speak with passengers who score high on the federal SPOT scale.
TSA will not say how many airports it added to the SPOT program after introducing it in Boston in 2002 and expanding it to Warwick and Portland, Maine, two years later.
Ann Davis, a TSA spokeswoman in Boston, said SPOT is in use full time at "a handful" of airports across the country and that a number of others took part in a two-week trial last month.
Some civil libertarians challenge the techniques as subjective, racially biased, probably ineffective at spotting a trained terrorist, and a waste of resources that could enhance security if used elsewhere.
TSA, an arm of the U.S. Department of Homeland Security, still considers SPOT an experimental program, Davis said. The agency expects to decide this year whether it works and should be put into practice at all airports.
In an interview last week, Salter endorsed the program, saying, "I personally see the value of it" at Green.
Salter, 60, is a former police officer and detective for the Port Authority of New York and New Jersey, and counted as "personal friends of mine" 25 of the 37 Port Authority employees killed in the 9/11 attack on the World Trade Center.
He was assigned to JFK, Newark and LaGuardia airports from 1973 to 1991, retiring as a detective sergeant.
He called the SPOT criteria an attempt to codify behaviors that every good beat cop practices instinctively.
"I cut my teeth on this stuff," he said.
TSA will not reveal the behaviors on the SPOT scorecard, but Salter said, "The public has a right to know what's going on and we have a duty to share with them the fact that there are things being done in their best interest. I think this is a worthwhile program and I have no problem saying it."
As one part of the array of security measures in place at Green, SPOT presents terrorists with one more obstacle to a successful attack, Salter said.
"Those people are opportunists," he said. "They'll seek a softer target," though no one can say whether Green was ever scouted by terrorists and abandoned as a potential target because of SPOT or any other aspect of its security program.
Salter said he was confident in the deterrent effect, but "how do you prove that you've deterred somebody?"
"We're looking for anything and everything" that might pose a threat, he said.
The SPOT criteria allow for "certain baseline behaviors" and tend to screen out "people who are nervous about flying," he said. "There are other behaviors that we're looking for."
He rejected any concern that officers might home-in on passengers for subjective, even unconscious reasons, and be more likely to perceive a high score on the SPOT criteria depending on the passenger's race or ethnicity.
"We've got a great training program," Salter said, expressing confidence that it teaches officers to watch for terror suspects who might look more like Timothy McVeigh, the Oklahoma City bomber, and not necessarily Mohammed Atta, a leader in the 9/11 attacks.
"We're looking at the behaviors, we're not looking at the person," he said.
TSA trains officers in the threat posed by counter-intelligence efforts, he said, terrorists who are "trying to ping the system" and see which behaviors single out passengers for additional screening.
"These guys are very smart at what they do; they're not stupid. Anybody who sells them short is making a mistake," Salter said.
The program at Green has never turned up a terrorist, or anyone on the government's "no-fly" list, but Salter said it routinely turns up undocumented aliens and passengers who are carrying illegal drugs or have arrest warrants outstanding.
"The behaviors are indicative of something going on with this person, exactly what it is can be sorted out after the police have had contact with them," he said.
If a passenger registers high enough on the anxiety scale, TSA requires additional screening before he or she is allowed to board a plane, Salter said. The transportation security officer who makes the call on a passenger may be working the security checkpoint, or may be a uniformed or plainclothes officer whose only job is to observe.
"On every shift we have people specially assigned" to SPOT, Salter said.
In all cases, a high score on the SPOT criteria means a trip through the bomb-sniffer (the Explosive Trace Portal), a pat-down search, "other security measures" or all of the above.
"We have a full range of screening techniques that we would use," Salter said.
In 2004 and again last year, TSA advertised for firms to propose emerging technologies that may be capable of removing the human factor in sizing up whether a passenger is nervous for extraordinary reasons and should receive extra scrutiny before boarding an aircraft. On the TSA's most recent appeal to the technology sector, Government Computer News reported the agency was interested in "desirable technologies for detecting suspicious behavior."
The technologies should be "useful for tracking travelers or employees in airports, train stations and bus terminals."
TSA said it should be "noninvasive, remote, covert, passive, automatic . . ." and able to detect "physiological response or overt behavior associated with malicious intent."
