aircraft operations. Laboratory testing occurred in the 400 area of Kirtland AFB and initial ground tests in hangar 1001, while the hangar at the Advanced Radiation Test Facility (ARTF) at the southeast corner of the runway was being constructed. ARTF was used for later ground tests that aimed the APT from the ARTF test pad to a target in the atmosphere in order to calibrate aircraft instruments in preparation for flight tests. Along with the five NKC-135, the 4900th FTG operated a fleet of five F-4Ds, one RF-4C, three NC-135As, five C-130s, and several A-37s, F-100s, and helicopters. These flights tests took place from January to July 1975, with the first "good" beam generation occurring in March. Testing ended in 1976, and although the airborne tests demonstrated the need to upgrade the tracker, the optical quality of the mirrors, and the stabilization of the APT, they clearly proved that a laser could be accurately pointed in an airborne environment. After 1977, work continued on the ALL, which would reach its goal in 1983. In 1979, AFWL achieved a milestone in the development of airborne high-energy laser weapons. The High Energy Laser Radar Acquisition and Tracking System (HELRATS) was designed specifically to track enemy aircraft and missiles. Installed at North Oscura Peak on the White Sands Missile Range between May and November 1979, HELRATS underwent extensive testing against aircraft and missiles. These tests were critically important steps to developing the DoD's high-energy laser program. Range tests took place from May to December 1979. The most successful of the tests was one that shot an AIM-9B downrange; the beam in the test cell delivered and locked onto the aim point on the missile dome, causing damage to the dome, guidance, and seeker unit inside the AIM-9B. This test demonstrated that the ALL systems could work as a unit and disable a target. In July 1980 a "hot firing" test of the system was made being the first airborne test of the system. The flight took place near WSMR at 10,000 feet. A series of airborne systems tests were then made prior to extracting a beam from the ALL. In January 1981 a high-energy laser beam was generated inside the ALL, directed through the APT, and propagated in the air outside the aircraft; this was the first demonstration that the ALL components could work as a unified system and point to a target.