OTTAWA - The public should take comfort that armed RCMP air marshals are riding commercial passenger flights and should not fear their presence will lead to wild-west shootouts, says the officer in charge of the program.

Supt. Alphonse MacNeil told the Air India inquiry Wednesday that the plainclothes officers -- assigned to selected flights according to the level of terrorist threat -- are trained in hand-to-hand combat and taught to use their "surgical'' shooting skills only as a last resort.

The aim is to avoid the kind of "shootout at the OK corral'' that could endanger passengers, MacNeil told the inquiry headed by former Supreme Court justice John Major.

"We give them firearms hoping that they'll never have to use them, but I'm confident when they do they'll do the right thing.''

The inquiry is studying air-security initiatives as part of its review of the 1985 downing of Air India Flight 182 with the loss of 329 lives. That attack by Sikh separatists used a luggage bomb, but the focus of anti-terrorist attention has shifted since al Qaeda used hijacked jets to mount the 9-11 attacks in the United States.

The RCMP started putting air marshals on Canadian flights to Washington, D.C., six years ago and has since expanded the program to other routes -- although exactly which ones and how many are carefully guarded secrets.

Air marshals have been used in the United States since the 1970s, but critics question the programs and cite the danger that mid-air shootouts could puncture an airliner's pressurized cabin or cripple vital hydraulic or electrical systems.

"I don't want to be sitting in an airplane at 35,000 feet while armed sky marshals are shooting it out with terrorists, because the likelihood is they will be my last moments,'' British aviation security expert Rodney Wallis told the inquiry in June.

"There is no place for a weapon of any sort in the cabin of an airplane.''

But two Canadian pilots, Craig Hall and Jean Labbe, testified earlier this week that modern aircraft can generally withstand any damage that could be caused by a handgun, and MacNeil said the Mounties have enlisted aircraft engineers and technicians to help officers learn how to shoot safely.

MacNeil also urged the inquiry to think about what could happen in the absence of air marshals.

"You have to be prepared to accept the fact that there's always going to be some risk in using a firearm,'' he said. "But does that risk outweigh the potential of someone taking over that aircraft and causing mass destruction?

"We don't feel it does. ... I hope if I'm on an aircraft and that situation occurs that there's an air marshal on board that can deal with it.''

Major didn't question the thoroughness of RCMP training or the accuracy of their marksmanship. But he did note there's really no way of knowing how good they are, since there hasn't been a confrontation aboard any Canadian airliner in the years the Mounties have been riding along.

"It's kind of a Catch 22,'' observed the judge. "If you don't have to do any shooting you can't demonstrate your skills. We don't know empirically whether they work or not.''

Nevertheless, Major didn't challenge the overall usefulness of the program and even suggested the general public might feel safer if people knew more about the initiative.

MacNeil readily agreed but said it's difficult to publicize the program because so many details -- including the precise training the Mounties undergo, the exact flights they travel on, and even the number of officers involved -- remain secret for security reasons.

''That's something that is one of the challenges I have to deal with in the next while,'' MacNeil said. "To figure out a marketing strategy to get that message out to the Canadian public.''