an optimized air superiority fighter to replace the F-4 Phantom II in counter-air and the F-106 Delta Dart in air defense roles and would not engage in multi-mission air-to-ground roles. Following operational test and evaluation, the first F-15A was delivered to TAC's 1st Tactical Fighter Wing at Langley AFB, Virginia in November 1974. Training on the new type, which also included twin seat F-15B versions, began at once. The A-10 Thunderbolt II, optimized as a close air support aircraft with emphasis on being able to defeat Soviet armor in the event of a Soviet/Warsaw Pact invasion of Western Europe, began arriving in March 1977 at Myrtle Beach AFB, South Carolina, equipping the 354th Tactical Fighter Wing. Finally, the F-16 Fighting Falcon, later nicknamed the "Viper," also entered the Air Force inventory, initially assigned to the 388th Tactical Fighter Wing at Hill AFB, Utah in January 1979. With the cost of acquiring the F-15 continuing to escalate in the early and mid-1970s, the F-16 was the successful design of the USAF Lightweight Fighter (LWF) competition, increasing overall USAF tactical fighter numbers with a multi-mission fighter that could replace those F-4 Phantom IIs not replaced by the F-15 in the air-to-air role and being able to concurrently assumed the F-4's role in air-to-ground / interdiction roles. Divestment of Tactical Airlift It was found during the Vietnam War that there was a large duplication of aerial port facilities and mission objectives between MAC, TAC and PACAF. A study group recommended the consolidation of all tactical airlift forces under MAC as a cost-saving measure under MAC and on 1 December 1974 all TAC and TAC-gained AFRES and ANG C-130 tactical airlift wings, groups and squadrons were reassigned to MAC. In 1975, PACAF and USAFE tactical airlift wings were also reassigned to MAC, thus ending the theater troop carrier mission as it had existed since the beginning of World War II. Inactivation of Aerospace Defense Command and assumption of the Continental Air Defense mission In early 1977, strong congressional pressure to reduce USAF management "overhead", and the personal conviction of the Air Force Chief of Staff that substantial savings could be realized without a reduction in operational capability, resulted in the disestablishment of Aerospace Defense Command (ADC) as a USAF major command. ADC was inactivated on 1 October 1979, with its "atmospheric" resources e.g., its Regular Air Force and Air National Guard F-101, F-102 and