In 1981 the United States Air Force bought eight American Airlines Boeing 707-320C aircraft at a cost of around 1.5 million dollars each with the initial intent to modify four of these aircraft to replace four of the aging EC-135N ARIA Aircraft.
The ARIA equipment was removed from one of the original eight ARIA EC-135N aircraft and installed in 81-0894.
Capabilities as of 1996
EC-18B - Basic TLM/Scoring with Horn Antenna - Acquires and tracks TM data using steerable 7 foot antenna. Provides worldwide HF voice communication and real-time UHF satellite data retransmission. Record, monitors and plays back mission data (2 - 14 track wide band recorders w/dubbing capability)
Source: Randy L. Losey