No RCMP bomb-sniffing dog was on duty at Toronto's Pearson airport when Air India Flight 182 departed in 1985, carrying hidden explosives, because all of the force's dogs and their handlers were at a course, an inquiry heard Tuesday.

That left the baggage loaded onto Flight 182 to be screened by an electronic detector that had failed a test conducted six months earlier, the Air India inquiry learned.

The inquiry in Ottawa is looking into the investigation of the bombing that killed 329 people as the flight was en route from Canada to India on June 23, 1985.

RCMP dog handler Gary Carlson, who was stationed in Toronto at the time, testified Tuesday that on June 22, 1985, he and his dog, Thor, were with all the other dogs and handlers at a yearly training course in Vancouver.

This was despite the fact that a heightened security protocol at the airport required a bomb-sniffing dog to be on duty.

Jacques Shore, a lawyer for the victims' families, asked Carlson how effective Thor might have been had he been at the airport that night.

"I would guess 70 to 80 per cent effective, depending on the amount of explosive," Carlson said.

Carlson said there was no backup dog at Pearson because, at the time, other police forces in the Toronto area didn't have canine teams capable of explosives work.

Should have conducted hand searches, but didn't

The standard procedure, in the absence of a dog, would have been to search baggage by hand, Carlson told the inquiry headed by former Supreme Court justice John Major.

It's known, however, that there were no hand searches that weekend. In addition, an X-ray machine broke down and Burns Security, the firm hired by Air India to screen its baggage, had to resort to an electronic sniffer that had failed its initial explosives-detection test.

Carlson said he tested the electronic sniffer at a meeting attended by Air India officials in January 1985 and demonstrated that it could detect gunpowder only if it was held within an inch of the substance.

Flight left Montreal before dog handler arrived

The inquiry heard last week from a former Quebec provincial police dog handler who said he believed he could have found explosives on Flight 182, but the plane had already left a Montreal airport by the time he arrived to check it.

Serge Carignan said he was called to the airport on June 22, 1985, hours before a bomb blew the flight out of the sky. Carignan said he was told that officials needed help searching a plane and luggage, and that the airport's regular RCMP explosives dog was out of the region.

By the time Carignan arrived at the airport roughly 45 minutes later, the plane had already taken off, he told the inquiry. Carignan said he didn't know why the plane departed before he got to the airport.

Flight 182 stopped in Montreal after leaving Toronto, en route to London's Heathrow Airport and then India.

The explosives — allegedly planted by Sikh extremists in luggage that was loaded in Vancouver — exploded off the west coast of Ireland and killed everyone on board, mostly Canadians. A related bomb killed two baggage handlers at a Tokyo airport.

The inquiry, which started in 2006, was called because the Air India investigation and prosecution was the costliest and one of the longest in Canadian history — yet led to no murder convictions.

Investigators believe extremists who wanted India to create an independent Sikh homeland carried out the bombings.

Only one person was ever convicted in the plot. Inderjit Singh Reyat pleaded guilty to manslaughter in 2003 and received a five-year sentence.

The suspected ringleader, Talwinder Singh Parmar, died in India in 1992 and the RCMP's two main surviving suspects were both acquitted in March 2005, after a 19-month trial.

With files from the Canadian Press