My dad flew 727s in the 1970s and 1980s. He’s told me that one’s course was maintained by manually dialing-in the VOR frequency and turning the heading bug so that it was aligned with the needle. The only autopilot modes were heading select and altitude hold. The airplane was hand-flown up to the cruising altitude, and again from descent onto the ground.
He advised me that today, however, most airlines that operate 727s, DC-9s, DC-8s, etc. will have upgraded their aircraft with FMCs and Inertial Navigation Systems. Can anyone comment as to whether or not such modifications have been widespread amongst airlines in the developed world, that still operate such aircraft? Furthermore, after an FMC and INS were installed, would an autopilot mode (something akin to modern-day LNAV and VNAV) have been added as well, so that the lateral/vertical course could be tracked?
Lastly, i’m only vaguely aware of what navigational methods long-range aircraft such as the DC-8 and 707 used when flying over vast distances of water, where there were no navaids. Could anyone elaborate? Were such navigation systems installed on the 727, 737-200, and other aircraft that were intended to be “short range”? Or was it just assumed that they would never cross vast waters?