The McDonnell Douglas/Boeing C-17 Globemaster III is a large military transport aircraft that was developed for the United States Air Force (USAF) from the 1980s to the early 1990s by McDonnell Douglas. The C-17 carries forward the name of two previous piston-engined military cargo aircraft, the Douglas C-74 Globemaster and the Douglas C-124 Globemaster II.

The C-17 is based upon the YC-15, a smaller prototype airlifter designed during the 1970s. It was designed to replace the Lockheed C-141 Starlifter, and also fulfill some of the duties of the Lockheed C-5 Galaxy. Compared to the YC-15, the redesigned airlifter differed in having swept wings, increased size, and more powerful engines. Development was protracted by a series of design issues, causing the company to incur a loss of nearly US$1.5 billion on the program's development phase. On 15 September 1991, roughly one year behind schedule, the first C-17 performed its maiden flight. The C-17 formally entered USAF service on 17 January 1995. Boeing, which merged with McDonnell Douglas in 1997, continued to manufacture the C-17 for almost two decades. The final C-17 was completed at the Long Beach, California plant and flown on 29 November 2015.^[2]

The C-17 commonly performs tactical and strategic airlift missions, transporting troops and cargo throughout the world; additional roles include medical evacuation and airdrop duties. The transport is in service with the USAF along with air arms of India, the United Kingdom, Australia, Canada, Qatar, the United Arab Emirates, Kuwait, and the Europe-based multilateral organization Heavy Airlift Wing. The type played a key logistical role during both Operation Enduring Freedom in Afghanistan and Operation Iraqi Freedom in Iraq, as well as in providing humanitarian aid in the aftermath of various natural disasters, including the 2010 Haiti earthquake and the 2011 Sindh floods.