The prototype and development aircraft were involved in an intensive operational testing program, along with the first C-141 to be delivered to MATS (63-8078) on 19 October 1964 to the 1707th Air Transport Wing, Heavy (Training),
Tinker Air Force Base, Oklahoma. The first delivery to an operational unit (63-8088) was conducted on 23 April 1965 to the 44th Air Transport Squadron, 1501st Air Transport Wing,
Travis Air Force Base, California. Although operational testing was still underway, as a consequence of the United States' military involvement in
South Vietnam, the C-141 was quickly dispatched to the region to commence operational sorties within the combat zone. The type became heavily used throughout the latter stages of the
Vietnam War, its transport capabilities being in high demand. Even following the arrival of large numbers of C-141s in the Vietnam theatre, the type was never able to replace the
C-124 Globemaster II fully due to its inability to transport
outsize equipment in-theatre; this situation was later addressed by the introduction of the even larger
C-5 Galaxy. The final duties performed by the C-141 in the conflict were repatriation flights, bringing home thousands of American
prisoners of war (POWs). Despite some operational issues experienced, the C-141 formed the backbone of the USAF's strategic airlift capability during the late 1960s; it continued to hold this status through to the late 1990s. On 8 January 1966, following the disestablishment of MATS, all C-141s were transferred to the newly established
Military Airlift Command (MAC). During October 1973, both the C-141 and the larger C-5 Galaxy airlifted supplies from the United States to Israel during the 1973
Yom Kippur War as part of
Operation Nickel Grass. Over the course of the operation, C-141s flew 422 missions and carried a total of 10,754 tons of cargo. By 1975, the C-141 fleet had reportedly accumulated an average of 20,000 flight hours each, two-thirds of their original rated life span. Specifically, the C-141 fleet was troubled by seemingly random cracking through the wing area, which was, according to a report compiled by the
Government Accountability Office (GAO), sometimes attributable to stresses imposed under certain types of missions undertaken. A planned remedial program during the 1980s to repair C-141
wing boxes uncovered significant corrosion and cracking, necessitating the replacement of all wing boxes across the fleet instead of making repairs. During the late 1970s, the USAF opted to commence a series of major upgrades to the C-141 fleet; not only was work started on a life extension program but, in 1977, the service also accepted a proposal from Lockheed to stretch several aircraft. over Antarctica The first strategic airlift flight of
Operation Desert Shield was flown by a MAC C-141 of the
437th Military Airlift Wing out of
Charleston AFB, SC, on 7 August 1990. The C-141 proved to be a workhorse airlifter of Operations Desert Shield and
Desert Storm, flying of cargo and 93,126 passengers during 8,536 airlift missions. In order to provide sufficient C-141s to meet intense demands, all scheduled maintenance activities were postponed, while the planned peacetime flight hours of the fleet were doubled. According to a GAO report, weight-related operational restrictions imposed upon the fleet have little effect on performance overall. On 1 June 1992, following the disestablishment of Military Airlift Command, all C-141s and the airlift wings to which they were assigned were transferred to the newly established Air Mobility Command (AMC).
Air Force Reserve Command (AFRC) and
Air National Guard (ANG) C-141s and units were also transferred to AMC. While the USAF was in the process of putting the fleet through a life extension program, numerous aircraft had reached well into their extended service life already, necessitating large numbers of C-141s to be withdrawn accompanied by tight limitations on the remaining fleet's flying hours being implemented during the 1990s. The GAO warned that, should another event on the scale of Desert Storm break out, the USAF would probably experience a significant shortage in airlift capabilities due to the high fatigue state of the fleet, and noted that the
C-17 Globemaster III intended to eventually replace the C-141 was experiencing delays. in December 2005. During 1994, one of the aircraft based at Wright-Patterson AFB was identified by its crew chief as the
Hanoi Taxi (AF Serial Number 66-0177), the first aircraft to land in North Vietnam in 1973 for
Operation Homecoming in the final days of the
Vietnam War, to
repatriate American POWs from
North Vietnam. Between 1996 and 1998, a C-141A was used as a towing aircraft in the
Eclipse project to demonstrate the possibility of using aerotow systems to bring towed winged vehicles to sufficient altitude to launch small satellites, the ultimate goal was to lower the cost of space launches. Six successful tests were flown with a modified
Convair F-106 Delta Dart, the QF-106 variant, in tow. A similar system can be seen in
SpaceShipTwo, whereby atmospheric engines carry a rocket-engined "second stage" to high altitude for launch. On 16 September 2004, the C-141 left service with all active USAF units, being confined to Air Force Reserve and Air National Guard units for the final two years of its operational service life. Between 2004 and 2006, multiple C-141s assigned to the Air Force Reserve's
445th Airlift Wing (445 AW) at
Wright-Patterson AFB were deployed to
Iraq and
Afghanistan, where they were typically engaged in the
medical evacuation (MEDEVAC) mission to repatriate wounded service members. In 2005,
Hanoi Taxi and other aircraft were marshalled by the USAF to provide evacuation for those seeking refuge from
Hurricane Katrina. This aircraft and others evacuated thousands of people, including the MEDIVAC of hundreds of ill and injured. With the 5 May 2005 announcement of the retirement of the last eight C-141s, the
Hanoi Taxi embarked on a series of flights, giving veterans, some of whom flew out of POW captivity in Vietnam in this aircraft, the opportunity to experience one more flight before retirement. On 6 May 2006, the
Hanoi Taxi landed for the last time and was received in a formal retirement ceremony at the National Museum of the United States Air Force, located at Wright-Patterson Air Force Base near
Dayton, Ohio. There are 14 C-141s, including the "Hanoi Taxi", now on static display at various air museums around the United States. All other airframes were retired to the "boneyard" at Davis-Monthan AFB, Arizona, where they were scrapped. ==Variants==