Canadian Privacy Commissioner Jennifer Stoddart is concerned about the potential unfairness of a plan to scrutinize the flying public's behaviour at the airport.

The federal government announced last year it would develop a passenger-behaviour observation program to detect terrorists.

Officers of the Canadian Air Transport Security Authority would be on the lookout for suspicious actions at air terminals, such as a traveller wearing a heavy coat on a hot day, or sweating profusely.

Stoddart says she's not convinced the techniques will actually help screening officers zero in on genuine threats.

"There is a huge possibility for arbitrary judgments to come into play," Stoddart said in an interview with The Canadian Press.

"This kind of initiative that doesn't have a clear scientific basis is extremely worrisome."

The program is the latest in a series of security measures that have exposed air travellers to new heights of surveillance since the 9/11 terrorist attacks a decade ago.

Stoddart's office has been closely monitoring a six-month pilot project carried out by the air security authority at the Vancouver airport to test the passenger observation concept.

The pilot, which concluded in July, involved about 20 uniformed observation officers scrutinizing and sometimes interacting with passengers, said air security authority spokesman Mathieu Larocque.

"These people were not roaming the airport. They were at the checkpoint in the queuing areas. They had a uniform. They were visible," Larocque said. "And they approached passengers and asked normal questions."

The air security authority, created following 9/11 to oversee air passenger screening, is analyzing data from the trial and preparing a formal assessment of the program's impact on privacy.

In May last year, just months after Canada embarked on the project, the U.S. Government Accountability Office questioned the very basis of a behaviour screening program run by the American Transportation Security Administration since 2003.

It noted the U.S. National Research Council's view that there is no scientific consensus on whether behaviour detection principles can be reliably used for counter-terrorism purposes.

Internal Transport Canada briefing notes, obtained under the Access to Information Act, acknowledge that passenger behaviour observation has "complex operational, policy, legal, privacy and human rights dimensions."

The Transport Department will "look at the GAO comments" as it develops policy for the use of behaviour detection and reviews the air screening authority's plan, the notes say.

But the department insists the methodology of passenger behaviour observation is based on decades of scientific research that demonstrates there are "certain involuntary, subconscious actions that can be indicative of deception."

"Without a PBO program in place, passengers are not being assessed to identify those persons who may present a threat to aviation security."

The government notes that in addition to the U.S., countries including Australia, Hong Kong, Indonesia, Israel, Russia and Singapore have either introduced or are developing similar behaviour-based initiatives for their air-security programs.

The Israeli approach, which features intensive questioning of passengers, has been criticized as a form of racial profiling due to its focus on people of Arab descent.

Canada's Transport Department insists its program must be "sensitive to the cultural diversity of the travelling public."

Still, some degree of racial profiling is bound to creep into the system, said Reg Whitaker, a distinguished research professor emeritus at Toronto's York University, and adjunct professor of political science at the University of Victoria.

"To some extent, it's going to happen. And whatever screening system is in place, a certain amount of ethno-cultural tension is the unfortunate result," said Whitaker, who chaired a 2006 advisory panel on the review of the law governing the air security authority and advised a recent federal inquiry into the 1985 Air India bombing.

Canadian transport officials tout behaviour observation as an additional layer of security that adds unpredictability to the screening process.

It is a process that has become ever more elaborate since the 9/11 attacks – from a clampdown on nail clippers and strict limits on liquids, to souped-up screening of hand baggage and millimetre-wave scanners that peer beneath a person's clothes.

Stoddart plans to issue an audit this fall on the air security authority's implementation of the controversial full-body scanners and use of surveillance cameras in airports – a nod to the fact air terminals offer a glimpse into the future.

"They seem to be the laboratory for new surveillance technology of the most sophisticated kind," Stoddart said.

But there's also a growing sense that all the poking and prodding has made the flying experience about as palatable as lukewarm airplane food.

The International Air Transport Association, a global alliance of airlines, has proposed a blueprint for checkpoint screening of the future – a "tunnel of technology" where all security and customs processing would take place seamlessly.

As the passenger strolls through, the tunnel could simultaneously scan the traveller's shoes, check for metal in pockets, and detect any liquids or explosives, said Dan Ebbinghaus, a vice-president with SITA, a company that specializes in air security technologies.

"It'd be just kind of nice if all that technology which is available could be more seamless."

Increased use of biometrics – unique identifiers such as iris scans – to move passengers through the airport could make the process simpler, he added.

For the foreseeable future, Canada's air security agency is focusing on refining current approaches, not a dramatic overhaul, said Larocque.

For instance, the security authority is testing screening technology that could allow passengers to pack the limited amounts of liquid they are allowed to bring onto planes inside their luggage – avoiding the need to present gels and perfume separately in transparent bags.

It is also looking at tweaking the full-body scanners to project a stickman-like image of the person being examined rather than a revealing outline of their form, Larocque said. "It just highlights the area of the body that could pose a threat."

The focus on better passenger screening has largely overshadowed the lack of comprehensive examination of cargo that is routinely loaded onto passenger aircraft.

The "firm hand of government" is required to ensure cargo is adequately examined, said Whitaker.

But it doesn't mean all the emphasis on scrutinizing passengers should be dismissed as mere "security theatre" – a show to make people feel safer in the sky.

The security measures are there as much to deter potential terrorists as they are for the general public, Whitaker said.

"Theatre, yes, but theatre has its uses as well."