|Courtesy of Capt. David O. Hill|
In Oct. 1970, with its entire fleet equipped with dual Litton LTN-51 INS (inertial navigation systems), Seaboard began trans-oceanic operations without navigators. This photo, taken in June 1971, shows the INS CDUs (control/display units) in N806SW, a DC-8-55F, during descent for landing at Anchorage. Both CDUs display the distance and time to the next waypoint. Two different CDU models were used, as seen here.