The support requirements for Apollo originally stated a need for twelve heavily instrumented, long-range, high-speed aircraft to supplement the telemetry and communication support provided by the Apollo ships. The operational requirements for the Apollo Range Instrumentation Aircraft (ARIA) stemmed from several considerations. During the long and critical second burn of the third-stage engine to inject the spacecraft into the trans-lunar trajectory, the spacecraft would travel a distance of about 1,800 miles. Accurate placement of the Apollo injection ship to capture this event made it impossible for the Apollo ship to obtain spacecraft telemetry and voice communication with the astronauts during that segment of the trajectory immediately preceding and during the first part of the injection burn. Specially instrumented aircraft at high altitude would be required to receive telemetry and function as line-of-sight relay stations for voice communications during that period. As the mission planning matured, with the decision to cover a single injection area only, the aircraft requirement changed, six to be on station, and two standby spares. The instrumentation aircraft could be used for general Range support when not required for Apollo.
The Air Force indicated a willingness to make available eight KC-135As for this purpose at no cost to NASA, provided NASA would pay for the required structural modifications and the procurement and installation of equipment necessary for Apollo support. In December 1964, a three-way agreement signed by the heads of the National Range Division (NRD) and the Electronic Systems Division (ESD) of the AFSC for the DOD, and OTDA for NASA, to acquire, test, and operate these needed range aircraft started the beginning of the Apollo Range Instrumentation Aircraft program.
Four additional KC-135Bs were obtained and structurally modified. They were nearly visually identical to the ARIA aircraft, except for engines installed and the planes displaying "US AIR FORCE" on the fuselage. In contrast, the ARIA Aircraft showed "UNITED STATES OF AMERICA." The history of the mission of these TRIA, Telemetry Range Instrumentation Aircraft, has been lost to time. The modification timeline is unknown, but I do know that two of these aircraft had the complete ARIA package installed and would supplement the ARIA program. The third aircraft eventually was modified as an RC-135S, and the fourth aircraft extensively modified to detect and analyze nuclear explosions and their related electromagnetic pulses.
Credit: Randy L. Losey
Editor: Randy L. Losey