McDonnell Douglas C-17 Globemaster III BC-17X

The MD-17 was the commercial derivative of the C-17 Globemaster III that McDonnell Douglas began to promote in the years before its 1997 merger with Boeing, at a time when the military programme itself was still fighting for survival. In December 1993 the Pentagon had temporarily capped C-17 procurement at 40 aircraft while it evaluated the airlifter's cost and performance and assessed commercial alternatives; under the Non-Developmental Airlift Aircraft programme opened in March 1994, a modified Boeing 747-400 and a restarted C-5 line were weighed against further C-17s. A civil version offered the manufacturer a way to widen the production base and gave the Department of Defense the prospect of extra outsize-cargo capacity without having to buy it outright.

The concept was tied from the start to the Civil Reserve Air Fleet (CRAF), the contractual arrangement under which selected US carriers commit aircraft that the Department of Defense can call up to extend military airlift during a national emergency. Because only US carriers fully certificated by the Federal Aviation Administration can take part in CRAF, the civil airlifter needed a commercial type certificate of its own. In September 1997 Flight International reported a first step: Boeing, which had just absorbed McDonnell Douglas, received an Organizational Designated Airworthiness Representative delegation from the FAA, allowing authorised company employees to inspect parts on the agency's behalf as part of the path towards MD-17 certification.

After the merger the project was renamed BC-17 and later BC-17X. The aircraft was to remain very close to the military C-17, but without the aerial-refuelling receptacle and without the on-board inert gas generating system, among other items of equipment a commercial operator would not need. The idea that resurfaced several times was that airlines would fly the aircraft commercially in peacetime and make them available to the military when called up, in a CRAF-like arrangement.

Boeing never found the customer base it needed. Flight International reported in October 2000 that commercial cargo plans for the C-17 had been revived, and in May 2007 C-17 programme manager Dave Bowman said the company was "the closest we've ever been" to launching the BC-17. Several customers had issued requests for proposals and Boeing held proposals from them, although it declined to name them; it spoke of an initial launch of 30 to 60 aircraft and of a market that "could be upwards of 100". One of the candidates was Global Heavylift Holdings, a private company led by Myron Stokes that was trying to raise 10.8 billion dollars in equity to buy 30 new C/BC-17s and was seeking an exemption from FAA rule FAR 21.27 to ease the civilianisation of the airframe.

The timing depended on the military line: C-17 production was then guaranteed only up to the last contracted aircraft, due in August 2009, and long-lead items had been placed under a stop-work order in March 2007. Commercial deliveries, together with new US and export military orders, were presented as a way to bridge that gap from 2010 onwards.

None of these attempts turned into a firm order. Analyses of the project point to the aircraft's economics: the C-17 burns roughly three quarters of the fuel per hour of a Boeing 747-400 while carrying only about half as many pallets, and its blunt nose and high-lift wing, optimised for military missions, made it expensive to operate as a freighter. Demand never materialised, the proposal to place the aircraft with operators under a contract allowing recall in wartime also failed to gain traction, and no airline ever took delivery of a BC-17X. The C-17 line carried on instead with military orders from the United States and allied air forces.