KANDAHAR, Afghanistan — Two CH-146 Griffon helicopters lifted off into the dim, grainy dusk above Kandahar Airfield one night last week and made straight for the mountains, in a new and completely unheralded chapter in the Afghan war.

This mission and the handful of ones before it are not something the air force eagerly broadcasts in its public relations campaign, but it is perhaps one of the most important life-saving duties the new air wing carries out.

Aircraft running lights were switched off once they cleared "the wire" allowing the grey and black camouflaged Griffons to blend in with the night sky.

Armed with night-vision goggles and a pod of darkness-piercing sensors, including high-definition cameras, the aircrews had set off on a deadly cat-and-mouse chase with the Taliban.

Two gunners on each aircraft leaned on their weapons through open doorways and looked down impassively as the lights of Kandahar city unfolded below them like irregular multi-coloured jewels cast on black velvet blanket.

The helicopters rose swiftly, brushed past the soaring volcanic peaks and then burst out over the desert, dropping to 152 metres, where the total blackness of the countryside enveloped them.

Although officially relegated to escort new CH-47D Chinook transport helicopters, the Griffons belonging to 408 Squadron were quietly given a new, more dangerous role soon after they deployed in December.

Their orders were to hunt insurgents who lace the roadways with home-made bombs, missions that depend on the murky world of classified intelligence.

Roadside bombs,have over the last three years exacted the single most deadly toll on Canadian soldiers, accounting for half of the 108 deaths.

That the Griffon could be useful in reducing the carnage has long been recognized in air force circles.

"Two kilometres to the road," Capt. Ben Massicotte, the commander of the second Griffon, declared over the intercom. "Keep your eyes open."

A tense silence followed.

The location of the road on this mission was classified, but was clearly one that NATO troops often used.

Twin cone-shaped lights of a pickup truck punctured the darkness and Capt. Greg Cowan, the flying officer, swung the chopper around to creep up behind the slow moving vehicle.

Massicotte quickly determined it was "only carrying junk" and not an explosive.

Ideally they hoped to catch the bombers in the act of digging into the hard-baked soil of dirt roads that spiderweb the desert -- or find them tunnelling under the few paved highways.

Occasionally, only U.S. surveillance drones have been that lucky, dispatching the night-time bomb-planters with a well-placed Hellfire missile, but there have never been enough of them in southern Afghanistan going around.

But even without actually spotting insurgents, the sensors and electronics carried by the CH-146s were powerful enough to detect changes in the landscape.

That the Griffons, a utility helicopter modified for combat and surveillance, were here at all is something of minor miracle.

Their deployment had been stubbornly opposed by National Defence since it was first proposed in December 2005, according to documents obtained by The Canadian Press under access to information laws.

The stated reason was that the helicopters, based on Bell 412 civilian model, didn't have engines powerful enough to handle the Afghan heat and high altitude flying -- a claim held to even though other allies in Kandahar flew similar light helicopters.

Remarkable there was resistance in Ottawa even though the Americans had demonstrated in 2007 success in Iraq with the U.S. army's once super-secret Task Force ODIN, which hunted roadside bombs in a similar way.

The federal government quietly spent $25 million with L-3 WESCAM last summer to provide the Griffons with the latest in sensory image technology, but insisted the helicopters weren't headed overseas.

Even when Ottawa announced it was buying the Chinooks, the initial plan called for the Griffons to be left home and gunships from other NATO countries to take up the escort duties.

That changed last fall, when the allies told Canada there were not enough AH-64 Apaches in Kandahar to go around.

The Griffons, it seemed, arrived by fluke.

"OK, this is it," Massicotte told the crew. "I want to look over by that compound over there."

The helicopter banked sharply.

On the right side, a dizzying splash of stars whipped past the open door, while on the left the grey desert floor turned counter clock-wise beneath them.

"Those are our LAVs over there," Cowan said, referring to a Canadian position.

"A little further," Massicotte urged. "There."

They had found something.

For the next while the Griffon tracked back and forth while the lead helicopter also examined the find.

On this night, two roadside bombs were confirmed by the patrol.

Missions such as this mean "a bit more than other missions" to Massicotte, 41, who has flown three different types of helicopters in over 20 years in the military.

"It seems everytime that there are casualties in theatre, we hear a lot they come from IEDs on the road, so if every time we go out we can catch a few of those ahead of time, it makes you feel good; definitely," said Massicotte, a native of Latuque, north of Trois Riviere, Que.

Capt. Brennan Cassidy, the mission commander that night, said mostly they don't know whether they've actually found something, but when they do it's rewarding.

Statistics on the Griffons success rate are classified.

But he said the fact that the helicopters are up there searching at night is no secret from the Taliban, who hear the choppers the coming.

"I'm quite certain they are aware of presence," Cassidy, a native of Kemptville, Ont., said after the flight.

"The nice thing, sometimes we may not have even specifically found something, but just our presence has prevented an IED from being implaced."