During February 1973 the Electronic Systems Division of the United States Air Force ordered two 747-200B airframes for conversion into Advanced Airborne National Command Post (AABNCP) aircraft. These were to be used as long range, mobile war rooms, to provide continuous (and relatively invulnerable) communication with American nuclear forces at times of dire national emergency. A third aircraft was odered in july 1973 and a fourth in December 1973 - although these two were not fully funded until FY-74/75: in 1976 it was announced that the total fleet would eventually increase to six aircraft, but such plans have long-since been dropped. The first two E-4A airframes (73-1676 and 1677) were both powered by 47900lb thrust JT9D-7W engines, but the third (74-0787) was powered by General Electric F103-GE-100s, the military equivalent of CF6-50E. These were not fitted with the big satellite-communications antenna or fuel-recieving equipment in the nose. This version is the GE 74-0787.
