OTTAWA - The American air force is letting Canada jump the assembly-line queue to acquire four giant Boeing transport planes within about 18 months.

"The United States air force, which has a fairly large order in train at the moment, has allowed us to step into the assembly line so we will get the aircraft quickly," Defence Minister Gordon O'Connor said Friday.

The first Canadian C-17 is expected to arrive by the end of August, with a second by the end of the year and the last two coming in the middle of next year. Under normal conditions, it would take years to build the Canadian order.

The $3.4 billion contract - $1.8 billion for the planes and $1.6 billion for 20 years of spares and maintenance - will be a windfall for Canadian industry, said Public Works Minister Michael Fortier and Industry Minister Maxime Bernier .

They said Boeing and Pratt and Whitney, maker of the plane's engines, have agreed to invest the face value of the contract in Canada and the benefits will boost defence and aerospace firms across the country.

Neither minister would offer any regional breakdown of the benefits, saying Boeing will be announcing a number of deals in the coming weeks.

Bernier said Boeing has already worked out $577 million in contracts with Canadian firms, with more to come.

The Bloc Quebecois has demanded that Quebec get the lion's share of the benefits because it has the largest chunk of the country's aerospace industry.

Gen. Rick Hillier, the chief of the defence staff, called it a great day for the Forces, which finally will have the capability to move big loads a long way by air.

O'Connor said the new planes will give the military a vital new capability.

"This marks the beginning of a new era for the Canadian Forces," he said. "Gone are the days when we had to rely solely on our allies or commercial companies for airlift to respond to crisis situations."

For instance, he said, it took two weeks to get the Disaster Assistance Response Team, or DART, into action after the Indian Ocean tsunami. With the C-17s, the team could have responded in two days.

The new planes will be based at CFB Trenton, home to most of the military's transport fleet. O'Connor said there will be "substantial" investment in new infrastructure there - hangars and other buildings - to handle the mammoth aircraft.

The purchase of the heavy-lift planes fulfils a promise the Conservatives made in the last election campaign.

Prime Minister Stephen Harper promised them in December 2005, saying they would give the Canadian Forces the ability to haul heavy loads, including the DART, without having to lease aircraft or beg a ride with allies.

"To put it bluntly, hitchhikers may get to their destination, but they don't get to pick the route or the timing," Harper said at the time.

Opposition politicians complained that the purchase was made without the usual tendering process, but the government countered by saying other firms were given a chance to compete, but none could meet the requirements.

In essence, the C-17 is unique and no other aircraft can match it.

The aircraft, which first flew in 1991, is widely used by the United States, which has 120 and is buying 60 more. Britain's Royal Air Force has four and plans to buy another and Australia took delivery of the first of four planes last December.

The planes are big - 53 metres long with a 52-metre wingspan - and can haul as much as 76 tonnes. They can be refueled in flight, giving them virtually unlimited range.

Despite their size, they can operate from runways as short as 1,100 metres.

The Conservatives are also in the process of replacing the aging fleet of C-130 Hercules transport planes, which have been the workhorse of the air force for decades, but which are rapidly coming to the end of their service lives.

The replacement is the C-130J, a completely revamped aircraft which looks much like a Hercules on the outside, but which has a new airframe, engines and electronics.

O'Connor said the C-130J assembly line is booked up, or he'd have them on delivery right away.

He said the government is still planning to buy new medium-to-heavy lift helicopters, new ships for the navy and new trucks for the army.