The Boeing C-17 Globemaster has proven extremely popular with the RAF and can operate in both strategic and tactical roles, combining transcontinental range with the ability to operate from short runways under basic conditions.
The C-17's huge capacity enables carriage of loads such as a Chinook helicopter or thirteen Land Rovers, or mixed freight loads of up to 160,000lbs (73,000kg).
The new C-17 aircraft will join the rest of the fleet at RAF Brize Norton in Oxfordshire when it enters service with the RAF in March 2011 after it has been fitted with self-protection measures.
This additional C-17 is part of the £900m package of enhancements for operations over the next three years announced by the Defence Secretary, Bob Ainsworth, in December 2009.
Mr Ainsworth said:
"Afghanistan remains our top priority and this extra C-17 represents a major contribution to the strategic airlift directly supporting our troops in Afghanistan.
"Since its entry into service in 2001, the UK's C-17 fleet has provided outstanding performance in RAF service in support of operations, humanitarian relief and routine tasks.
"The additional aircraft will allow our strategic transport capacity to be expanded during a period of intensive coalition operations."
A Royal Air Force Merlin helicopter is loaded onto a C-17 Globemaster aircraft at Brize Norton for transportation to the USA for Exercise Merlin Vortex
[Picture: SAC Neil Chapman, Crown Copyright/MOD 2009]
Officer Commanding 99 Squadron, Wing Commander Simon Edwards, said:
"The operational record of the C-17 is unsurpassed. The current fleet of six aircraft deliver an incredible capability to our deployed forces and the announcement of a seventh aircraft will mean a great deal not only to the RAF but to the soldiers on the front line.
"There is no better way - and often no other way - to get vital equipment such as helicopters and large vehicles, such as Mastiff, where they are needed and when they are needed."
Six RAF C-17s are operated by 99 Squadron from their base at RAF Brize Norton. Since the first aircraft was delivered in 2001, the RAF C-17 fleet has flown well over 50,000 hours, largely in support of operations in Iraq and Afghanistan, but also including humanitarian relief work in South East Asia and Pakistan.
It can carry a number of different equipment types. For instance it can carry a Chinook helicopter or three Apache helicopters or three Warrior vehicles or 13 Land Rovers or even a Tornado F3 fighter.
Configurations can vary but as an example it can transport 100,000lbs (45,500kg) of freight over 4,500 nautical miles (8,000km), flying above 30,000 feet (9,000 metres).