Boeing C-17B Advanced Globemaster III. Also includes bonus k its of Shorts C-23A, Fairchild C-26B and Cessna UC-35B. In 1980, the USAF found some of the C-141s had major structural problems as a result of heavy use. In response, McDonnell Douglas elected to develop a new aircraft using the YC-15 as the basis. McDonnell Douglas won the contract to build its proposed aircraft, by then designated the C-17A Globemaster III. Development problems and limited funding caused delays until the late 1980s. By the mid-1990s, most of the problems had been resolved. The first production model was delivered to Charleston Air Force Base, South Carolina in 1993. The first squadron of C-17s was declared operationally ready in 1995. In 1997 McDonnell Douglas merged with Boeing. The US DoD and Boeing are considering further follow-on orders. In 1998, Boeing proposed upgrade package for transforming the C-17A into a true tactical airlifter, the C-17B. The package included higher thrust engines, double-slotted flaps, adding centre main landing gear, engine / landing control systems and major software upgrades.