C-17 Globemaster III ladning after demo at 2009 Aviation Nation Air ShowThe Boeing (formerly McDonnell Douglas) C-17 Globemaster III is a large military transport aircraft.The  C-17 was developed for the United States Air Force from the 1980s to the early 1990s by McDonnell Douglas. The aircraft carries on the name of two previous United States military cargo aircraft, the C-74 Globemaster and the C-124 Globemaster II. The C-17 Globemaster III is used for rapid strategic airlift of troops and cargo to main operating bases or forward operating bases throughout the world. It has the ability to rapidly deploy a combat unit to a potential battle area and sustain it with on-going supplies. The C-17 is also capable of performing tactical airlift, medical evacuation and airdrop missions.
In the 1970s, the US Air Force began looking for a replacement for the C-130C-17 Globemaster III climbing into the deep blue skies over Nellis Air Force Base Hercules tactical airlifter. The Advanced Medium STOL Transport (AMST) competition was held, with Boeing proposing the YC-14, and McDonnell Douglas proposing the YC-15. Though both entrants exceeded specified requirements, the AMST competition was canceled before a winner had been selected. The Air Force subsequently started the C-X program to develop a larger AMST with longer range to augment its strategic airlift, this program was later canceled by the Pentagon.

C-17 Globemaster III banking during demo at 2009 Aviation Nation Air ShowBy 1980, the USAF found itself with a large fleet of aging C-141 Starlifter cargo aircraft. Compounding matters, USAF historically never possessed sufficient strategic airlift capabilities to fulfill its airlift requirements. The USAF set mission requirements and released a request for proposals (RFP) in October 1980. McDonnell Douglas elected to develop a new aircraft using the YC-15 as the basis; Boeing bid an enlarged version of its AMST YC-14. Lockheed submitted two designs, a C-5 based design and an enlarged C-141 design. McDonnell Douglas was selected to build its proposed aircraft on 28 August 1981, by then designated C-17. The new aircraft differed in having swept wings, increased size, and more powerful engines. This would allow it to perform all work performed by the C-141, but to also fulfill some of the duties of the C-5 Galaxy, freeing the C-5 fleet for larger outsize cargo.