[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 USAF started the C-X program in November 1979 to develop a larger AMST with longer range to augment its strategic airlift.

[6] This would allow it to perform the work done by the C-141, and to fulfill some of the duties of the Lockheed C-5 Galaxy, freeing the C-5 fleet for outsize cargo.

[13] The maiden flight of the C-17 took place on 15 September 1991 from the McDonnell Douglas's plant in Long Beach, California, about a year behind schedule.

[14][15] The first aircraft (T-1) and five more production models (P1-P5) participated in extensive flight testing and evaluation at Edwards Air Force Base.

[6] In late 1993, the Department of Defense (DoD) gave the contractor two years to solve production issues and cost overruns or face the contract's termination after the delivery of the 40th aircraft.

[22] In April 1994, the program remained over budget and did not meet weight, fuel burn, payload, and range specifications.

The report also stated "current military doctrine that does not reflect the use of small, austere airfields", thus the C-17's short field capability was not considered.

[41] Debate arose over follow-on C-17 orders, the USAF requested line shutdown while Congress called for further production.

[55] In May 2015, The Wall Street Journal reported that Boeing expected to book a charge of under $100 million and cut 3,000 positions associated with the C-17 program, and also suggested that Airbus' lower cost A400M Atlas took international sales away from the C-17.

The size and weight of U.S. mechanized firepower and equipment have grown in recent decades from increased air mobility requirements, particularly for large or heavy non-palletized outsize cargo.

[83] In 2021, the Air Force Research Laboratory further developed the concept into tests of the Rapid Dragon system, which transforms the C-17 into a lethal cruise missile arsenal ship capable of mass launching 45 JASSM-ER with 500 kg warheads from a standoff distance of 925 km (575 mi).

There were an unknown number possibly crushed and killed by the landing gear retracting, with human remains found in the landing-gear stowage.

[86][87][88] Also that day, C-17 01-0186 from the 816th Expeditionary Airlift Squadron at Al Udeid Air Base transported 823 Afghan citizens from Hamid Karzai International Airport on a single flight, setting a new record for the type,[89] which was previously over 670 people during a 2013 typhoon evacuation from Tacloban, Philippines.

[90] Boeing marketed the C-17 to many European nations including Belgium, Germany, France, Italy, Spain and the United Kingdom.

Although it was to be a fallback for the A400M, the Ministry of Defence (MoD) announced on 21 July 2004 that they had elected to buy their four C-17s at the end of the lease,[93] though the A400M appeared to be closer to production.

[104] On 13 September 2022, C-17 ZZ177 carried the body of Queen Elizabeth II from Edinburgh Airport to RAF Northolt in London.

[105] The Royal Australian Air Force (RAAF) began investigating an acquisition of strategic transport aircraft in 2005.

RAAF aircraft were ordered directly from the USAF production run and are identical to American C-17s even in paint scheme, the only difference being the national markings, allowing deliveries to commence within nine months of commitment to the program.

[112] Several days later the aircraft flew from Hickam Air Force Base, Hawaii to Defence Establishment Fairbairn, Canberra, arriving on 4 December 2006.

[115] On 18 April 2011, Boeing announced that Australia had signed an agreement with the U.S. government to acquire a fifth C-17 due to an increased demand for humanitarian and disaster relief missions.

[117] On 23 September 2011, Australian Minister for Defence Materiel Jason Clare announced that the government was seeking information from the U.S. about the price and delivery schedule for a sixth Globemaster.

[122][123] Prime Minister Tony Abbott confirmed in April 2015 that two additional aircraft were to be ordered, with both delivered by 4 November 2015;[124] these added to the six C-17s it had as of 2015[update].

[55] The Canadian Armed Forces had a long-standing need for strategic airlift for military and humanitarian operations around the world.

In 2002, the Canadian Forces Future Strategic Airlifter Project began to study alternatives, including long-term leasing arrangements.

After Typhoon Haiyan hit the Philippines in 2013, Canadian C-17s established an air bridge between the two nations, deploying Canada's DART and delivering humanitarian supplies and equipment.

[139] At the 2006 Farnborough Airshow, a number of NATO member nations signed a letter of intent to jointly purchase and operate several C-17s within the Strategic Airlift Capability (SAC).

[141][142] SAC members are Bulgaria, Estonia, Finland, Hungary, Lithuania, the Netherlands, Norway, Poland, Romania, Slovenia, Sweden and the U.S. as of 2024.

[179] In June 2013, The New York Times reported that Qatar was allegedly using its C-17s to ship weapons from Libya to the Syrian opposition during the civil war via Turkey.

[191][192] Data from Brassey's World Aircraft & Systems Directory,[230] U.S. Air Force fact sheet,[59] Boeing[231][232]General characteristics Performance Avionics