NASA Astronaut Group 1. The Bien Hoa Air Base Vietnam May 16, 1965 Conflagration/Fire Accident Investigation Board concluded that the disaster was caused by the accidental explosion of a bomb on a parked B-57 triggering a series of blasts. The aircraft and the ammunition were stored too close together which allowed the fires and explosions to spread. The accident investigation board recommended improvements. In the face of such experience, engineers initiated a major program to construct revetments and aircraft shelters to protect individual aircraft. The 10 surviving B-57s were transferred to Tan Son Nhut Air Base and continued to fly sorties on a reduced scale until replacement aircraft arrived from Clark AB. As the B-57B was withdrawn from active front-line service, some B-57Bs had to be transferred to Vietnam from the Kansas Air National Guard, and 12 B-57Es had to be withdrawn from target-towing duties and reconfigured as bombers to make good these losses. In June 1965, the B-57s were moved from Tan Son Nhut Air Base to Da Nang Air Base. On 23 June the 416th Tactical Fighter Squadron equipped with F-100D Super Sabres moved from Da Nang Air Base to Bien Hoa. On 13 July 1965 the newly arrived 307th Tactical Fighter Squadron also equipped with F-100Ds arrived at the base. 3rd Tactical Fighter Wing On 8 November 1965 the 3d Tactical Fighter Wing moved to Bien Hoa, becoming the host unit at the base. The 3rd TFW briefly absorbed the assets of the 1st and 602nd Air Commando Squadrons, however in January 1966 the 1st Air Commando Squadron moved to Pleiku Air Base and the 602nd Air Commando Squadron moved to Nha Trang Air Base. On 8 February 1966 the 90th Tactical Fighter Squadron equipped with F-100Ds arrived at Bien Hoa. F-100 units attached to the 3rd TFW were: 90th Tactical Fighter Squadron, 8 February 1966 - 31 October 1970 307th Tactical Fighter Squadron, 21 November - 6 December 1965 308th Tactical Fighter Squadron, 2 December 1965 – 25 December 1966 416th Tactical Fighter Squadron, 16 November 1965 - 15 April 1967 429th Tactical Fighter Squadron, 21 November - 14 December 1965 510th Tactical Fighter Squadron, 8 November 1965 – 15 November 1969 531st Tactical Fighter Squadron, 7 December 1965 – 31 July 1970 Other attached units were: 1st Air Commando Squadron, 21 November- 8 March 1966 8th Attack Squadron (later redesignated 8th Special Operations Squadron), 15