C-17 Globemaster III

The Boeing C-17 Globemaster III is a four-engined strategic transport aircraft developed by McDonnell Douglas for the United States Air Force to replace the C-141 Starlifter and take over part of the outsize-cargo work of the C-5 Galaxy. It first flew on 15 September 1991, reached operational status in January 1995, and 279 were built at Long Beach, California, before the line closed in 2015. The type combines intercontinental range with the ability to carry an M1 Abrams tank into short, austere airfields, and it equips the USAF alongside the air forces of the United Kingdom, Australia, Canada, India, Qatar, the United Arab Emirates and Kuwait and the NATO-hosted Strategic Airlift Capability.

Development

The C-17 descends from the Advanced Medium STOL Transport (AMST) competition of the 1970s, in which the USAF sought a jet replacement for the C-130 Hercules: Boeing flew the YC-14 and McDonnell Douglas the YC-15, and the programme was cancelled without a winner. In November 1979 the USAF opened the C-X programme for a larger, longer-ranged derivative to bolster strategic airlift as its C-141 fleet aged, and on 28 August 1981 selected McDonnell Douglas's scaled-up YC-15, with swept wings and more powerful engines, over Boeing and Lockheed proposals.

Funding lagged and full-scale development was only contracted in December 1985, for a requirement of 210 aircraft. Design problems pushed first flight back to 15 September 1991, a year late, and in April 1990 the order had been cut to 120. The programme then nearly collapsed. A static-test wing failed in October 1992 at 128 percent of limit load against a 150 percent requirement, forcing a $100 million redesign. In late 1993 the Department of Defense capped the buy at 40 aircraft and gave the contractor two years to fix production and cost problems or face termination, and studied a Boeing 747-400 freighter and a C-5D as alternatives. Accepting those terms cost McDonnell Douglas close to $1.5 billion on the development phase, but by September 1995 the type was meeting its performance and reliability targets.

The Department of Defense ordered the remaining 80 of the 120 in 1996, and Boeing inherited the programme on merging with McDonnell Douglas in 1997. The USAF order rose to 180 in 2002, 205 in 2009 and finally 223, the last USAF delivery coming on 12 September 2013, plus a 224th ordered in 2012 to replace the aircraft lost at Elmendorf in 2010. Boeing cut the rate from 16 to 10 aircraft a year in 2010 and built the last airframes without firm customers. The 279th and final aircraft was delivered in 2015 and the Long Beach plant closed. In June 2025 Boeing said it was in talks with an international customer about restarting production, and Japan's government had signalled interest in the type.

Design

The C-17 is a high-wing, T-tailed airlifter 174 ft (53 m) long with a span of 169 ft 10 in (51.8 m). Four Pratt & Whitney F117-PW-100 turbofans, military derivatives of the PW2040 fitted to the Boeing 757, each deliver 40,440 lbf (179.9 kN). Their thrust reversers direct exhaust upward and forward, limiting debris ingestion and letting the aircraft back up under its own power on a narrow taxiway; at idle reverse they can also be used in flight for steep descents. It can operate from strips of 3,500 ft (1,067 m), only 90 ft (27 m) wide, paved or not.

The cargo compartment is 88 ft (27 m) long, 18 ft (5.5 m) wide and 12 ft 4 in (3.76 m) high, loaded through a rear ramp over a floor that converts between pallet rollers and a flat deck. Maximum payload is 170,900 lb (77,500 kg) and maximum takeoff weight 585,000 lb (265,000 kg), enough for one M1 Abrams, two Bradleys or three Strykers, 102 paratroopers or 134 passengers. With 157,000 lb (71,200 kg) aboard the range is about 2,420 nmi (4,480 km), and the ferry range 6,230 nmi (11,540 km); from Block 13 (2001) a sealed centre wing bay serves as an extra tank, known informally as the C-17 ER. It cruises at Mach 0.74–0.79, around 830 km/h. The flight crew is two pilots and a loadmaster. Block 16 and 21 upgrades added fuel-tank inerting, a new weather radar, ADS-B and navigation and flight-management improvements.

Operational History

Entry into service and the 1990s

Charleston AFB in South Carolina received the first production C-17 on 14 July 1993, and the 17th Airlift Squadron was declared operational on 17 January 1995. The type won the Collier Trophy for 1994. Over Kosovo in 1999 it flew half of Operation Allied Force's strategic airlift missions, much of it into small airfields. Since 1999 it has also flown the annual Operation Deep Freeze resupply of McMurdo Station in Antarctica.

Afghanistan and Iraq

The C-17 became the backbone of the air bridge to Afghanistan and Iraq. On 26 March 2003, 15 aircraft dropped about 1,000 paratroopers of the 173rd Airborne Brigade onto Bashur in northern Iraq, the largest combat airdrop since Panama in 1989, then ferried in M1 Abrams, Bradleys, M113s and artillery. The fleet also carried allied equipment, among them 15 Canadian Leopard C2 tanks flown from Kyrgyzstan to Kandahar in 2006. A surface-to-air missile disabled one engine of a C-17 climbing out of Baghdad on 10 December 2003; it landed safely.

Humanitarian and allied operations

Globemasters delivered relief after the 2010 Haiti earthquake, the 2011 Sindh floods, Typhoon Haiyan in 2013 and the 2023 Türkiye-Syria earthquakes. In January 2013 RAF C-17s moved French armoured vehicles into Bamako for the intervention in Mali, with American, Canadian and SAC aircraft also supporting the operation. On 13 September 2022 RAF C-17 ZZ177 flew the coffin of Queen Elizabeth II from Edinburgh to RAF Northolt. On 16 March 2024 an Indian Air Force C-17 flew a 10-hour round trip to an area 2,600 km away to drop marine commandos and two raiding craft near the hijacked MV Ruen off Somalia, enabling the Indian Navy to retake the ship.

Kabul 2021 and the 2020s

The evacuation of Kabul on 15 August 2021 produced the type's most widely seen images. C-17 02-1109 of the 62nd Airlift Wing took off from Hamid Karzai International Airport with people clinging to the fuselage, at least two of whom fell to their deaths. The same day C-17 01-0186 carried 823 Afghan civilians out on a single flight, a record for the type.

The USAF has also tested the aircraft as a stand-off weapons carrier: under the Air Force Research Laboratory's Rapid Dragon programme, palletised cruise missiles are launched from transport aircraft, a C-17 being able to carry up to 45 JASSM-ERs. On 4 March 2025 a C-17 parked at Perot Field Fort Worth Alliance Airport, Texas, suffered wing damage when two unoccupied business jets were blown into it during a windstorm.

Operators

As of 2026 the USAF operates around 220 C-17s across active-duty, Air National Guard and Air Force Reserve units, with main operating bases at Charleston, Dover, McGuire, Travis and McChord and training at Altus. The Royal Air Force flies eight C-17A ERs with Nos. 24 and 99 Squadrons at Brize Norton; the Royal Australian Air Force eight with No. 36 Squadron; the Royal Canadian Air Force five CC-177s with 429 Transport Squadron at Trenton; the Indian Air Force 11 with No. 81 Squadron at Hindon, the last delivered in August 2019; Qatar and the United Arab Emirates eight each and Kuwait two. The Strategic Airlift Capability's Heavy Airlift Wing at Pápa Air Base, Hungary, operates three aircraft, two bought jointly and one contributed by the United States, for twelve nations with multinational crews.

Accidents

The only hull loss and only fatal accident to date was on 28 July 2010, when 00-0173 stalled and crashed at Elmendorf Air Force Base, Alaska, during air show practice, killing the four crew. Repairable incidents include a runway overrun at Bagram in 2005, a gear-up landing there in 2009 and an overrun at Forward Operating Base Shank in 2012 repaired at a reported $69.4 million.

Future and Replacement

No replacement is in production. The USAF's Next-Generation Airlifter is intended to succeed both the C-17 and the C-5M with a single aircraft, with an analysis of alternatives in fiscal 2027, procurement from about 2038 and initial operational capability around 2041; under current planning the C-17 must serve to about 2075.

Variants

• C-17A: Production airlifter; 279 built; the T-1 prototype was retired in 2012.
• C-17A ER: Unofficial designation for aircraft with the sealed centre wing bay fuel tank, standard from Block 13 in 2001.
• CC-177 Globemaster III: Royal Canadian Air Force designation for its five C-17A ERs.
• C-17B: Proposed tactical version with double-slotted flaps, an extra centre-fuselage main gear and more powerful engines, offered in 2007; not built.
• MD-17 / BC-17X: Proposed commercial freighter for Civil Reserve Air Fleet carriers; none ordered.