Ottawa has procured another C-17 military transport aircraft, bringing the total number of C-17s in the Royal Canadian Air Force's fleet to five.

Defence Minister Rob Nicholson announced the purchase of the Boeing-made plane on Friday at Canadian Forces Base Trenton

He said the additional C-17 will ease the burden on the current fleet, and will extend the life expectancy of all five planes by about seven-and-a-half years.

"Having a fifth C-17 will significantly augment the flexibility of the Canadian Armed Forces strategic airlift," Nicholson said.

The C-17 Globemaster III – which in Canada is designated as the CC-177 Globemaster III -- is a four-engine long-haul aircraft that can transport large equipment, supplies and troops directly to small airfields anywhere in the world, according to Boeing.

It has a carrying capacity of nearly 75,000 kilograms and has been used in cargo deliveries since the 1990s.

Gen. Tom Lawson, chief of the defence staff, said in a statement that the massive planes allow the military to remain flexible, as they can perform several different operations on short notice.

The Department of Defence said the acquisition project cost (meaning the cost of the plane during its entire lifespan) is estimated at $415 million, with an additional $30 million for 12 years of in-service support.

With the purchase of the additional plane, it is estimated that the RCAF will have at least three C-17s available more than 90 per cent of the time to respond to any type of international or domestic crises, Nicholson said in a statement.

Currently, Canada's C-17s are being used to ferry supplies to Canadian Forces in Kuwait who are participating in Operation Impact. They have also been used to deliver supplies to Canada's CF-18s, which are stationed in Lithuania and taking part in Operation Reassurance in response to the crisis in Ukraine.

The planes have also been used in humanitarian operations, such as in 2013, when they were used to support French troops fighting in Mali.

In addition to Canada, the plane is currently used by the U.S., U.K., Kuwait, Australia, Qatar and the United Arab Emirates.