I knew this had to be Diego.
3.8 hours into a 4.6 flight? I'd consider it safe to continue, but that's based on knowledge of my aircraft. The IRUs won't drift significantly in 0.8 hours, even without a position fix from the GPS or DME/DME. But again, I have no knowledge of the DC-8, and for them it may have been better to turn around. There is absolutely no need to jeopardize safety or put the crew in a legal situation just to complete the mission.
And sorry MikeD, I'm a young whippersnapper.
Random aside since ETOPS was brought up: In my two-engine jet, if you're inside of an hour, you've already exited ETOPS. Not a factor.
Being AOG in DG wouldn't be ideal I spent some time there in 1980 on a C-5 trip staging out of Clark. This was back in the days of the *Party Pack*. They escorted the entire crew to the trailer they had reserved exclusively for us and gave us a box with hot dogs, hamburgers, chips and soda. We spent the day exploring the beach and had a barbeque that evening. We restocked their BX with beer on one of our legs.
Wouldn't want to live there, but it was a beautiful place.