The C-17 is now a proven performer, capable of taking off from runways as short as 7,600 feet and landing on runaways as short as 3,000 feet. They feature an in-flight refueling capability that allows for extended operational ranges - a requirement of strategic and tactical airlifters anywhere in the world, particularly when attempting to move a massive army. A single C-17 can haul as much as 160,000lbs of cargo (including whole armored vehicles) out to 2,760 miles. Indeed, a single C-17 can move up to three Bradley Infantry Fighting Vehicles in one lift and holds the capability to haul the M1 Abrams Main Battle Tank -both vehicles represent primary components of the American Army and Marine Corps. A loading ramp at the rear of the fuselage (under the empennage) provides the needed access to the hold. Beyond its take-off and landing qualities, the C-17 is also cleared to airdrop up to 60,000lbs of palletized cargo at a time. In-cockpit equipment allows both pilots to operate their aircraft in low- or no-light periods for a highly useful "all-weather" capability. It further features twin Head-Up Displays (HUDs), four Multi-Function Displays (MFDs) and an all-modern digitally-minded instrument panel. When configured as a passenger transport, the C-17 can seat 102, making it an ideal infantry transport, MEDEVAC unit (36 litters) or humanitarian "people-mover". A dedicated loadmaster serves as the rest of the standard three-man crew. The undercarriage makes use of four three-wheeled main landing gear legs (held under the aircraft's center-mass) and a twin-wheeled nose leg. The nose leg is steerable for ground maneuvering. The undercarriage is specifically designed with a low profile to facilitate loading and unloading of the aircraft.
Dimensionally, the C-17 sports a wingspan of 170 feet with length of 174 feet and height of 55 feet. Controls are given a quadruple-redundancy as well as mechanical backup in emergencies. Power is served through 4 x Pratt & Whitney F117-PW-100 turbofan engines each delivering 40,440lbs of thrust. Performance numbers include a cruise speed of 515 miles per hour with a service ceiling up to 45,000 feet . Empty weight is 282,500lbs with a listed maximum take-off weight nearing 585,000lbs. With a 150,000lb payload, the C-17 can range out to 5,185 kilometers (2,800 nautical miles).
There is only one major (and official) C-17 variant and this remains the original "C-17A" airlifter model. C-17A "ER" is an unofficial marker used for C-17s granted "extended range" through implementation of a center-wing fuel tank. These appeared in 2001 and "winglets" at each wingtip have since been added for further fuel efficiency. The C-17B is a proposed, improved C-17A promoted by Boeing which would incorporate higher rated engines providing more power, use of double-slotted flaps at the wings, a revised undercarriage and improved runway performance.
The C-17 has seen use in military circles beyond American shores. The Royal Australian Air Force operates six C-17ER models through No. 36 Squadron. The Royal Canadian Air Force manages four C-17ER airframes (as the CC-177) through 429 Transport Squadron. The Indian Air Force is on the books for 10 total C-17s of which five were already on hand for No. 81 Squadron. Qatar has taken on delivery of four C-17As while the United Arab Emirates utilizes six such airframes. The United Kingdom has purchased eight C-17ER models and fields them through No. 99 Squadron. NATO operates three C-17s out of Papa Air Base, Hungary.