In 1981 the United States Air Force bought eight American Airlines Boeing 707-320C aircraft at the 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.
81-0891 was delivered to American Airlines on August 31, 1967, registered as N7598A and was the first of the American Airlines aircraft to be modified for the ARIA mission. The modification of this first Boeing 707-320C aircraft involved 300,000 working hours.
The ARIA equipment was removed from one of the original eight ARIA EC-135N aircraft and installed in 81-0891.
On February 12, 1982, N7598A, was delivered to the United States Air Force and then extensively modified at Wright-Patterson Air Force Base to perform the ARIA mission. On January 4, 1985, ARIA aircraft 81-0891 was placed in the United States aircraft inventory as the only EC-18B in existence.
The equipment installed in 81-0891 was the typical ARIA set up with the addition of the SMILS system. SMILS was the Sonobuoy Missile Impact Locating Systems, which used to score MIRV re-entries in the Kwajalein and Kodiak ranges.
The SMILS aircraft had the left-wing painted black with red insignia. The blackened wing reduced glare reflected off the wing during re-entry reducing the glare to the high-speed cameras that filmed out of the port windows.
Capabilities as of 1996
EC-18B - Basic TLM - Acquires and tracks TM data using a steerable 7-foot antenna. Provide 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)
81-0891 flew the last ARIA mission on August 24, 2001, staging the mission from Ascension Island. In June of 2013, 81-0891 was auctioned off for scrap at the Northrup-Grumman facility at Lake Charles, Louisiana.
Source: Randy L. Losey