Originally Posted by
Akrotiri bad boy
my mind keeps returning to the 737's of my youth; …. Is the aircraft at the edge of its duration envelope?
Go back a bit further in time. Sterling Airways, a charter carrier from Denmark at the time, operated by 1969 (way before ETOPS was thought of) regular flights from Copenhagen to Los Angeles with the CARAVELLE ! They routed Copenhagen-Keflavik-Gander-Omaha-Los Angeles. Just one crew change, at Gander. They had previously run the flights with their propeller DC-6Bs, which had been quite capable of an Atlantic crossing from their introduction in the early 1950s. I think Sterling were the first to run "medium range" jets across the North Atlantic.
Don't believe it ? Here's a photo of one at LAX
https://www.jetphotos.com/photo/7402490
They also operated Caravelles from Copenhagen to Thailand, via the Middle East, and to Natal in Brazil routing via the Canaries, which last they also served very regularly. Copenhagen to Las Palmas must be further than Glasgow to St Johns Nfld.