To cross the Atlantic with a twin-engined plane has that requirement (ETOPS).
I enjoyed the history of ETOPS-138 [0]. ETOPS-120 leaves some small triangles of the Atlantic inaccessible, particularly if one emergency airfield is unavailable. A 15% increase to 138 minutes covers it.
Anecdotally, though, my experience as a commercial passenger feels like airlines fly almost directly over pacific islands rather than within X minutes of diversion. My memory may be anchored in bygone years.
[0] https://aviation.stackexchange.com/questions/30979/why-etops...
> pacific islands
Depending on the jet streams, the flight can take the great circle route [0] or taking advantage of the jet stream [1] and flying more southernly
[0] https://flightaware.com/live/flight/JAL6/history/20230108/02... [1] https://flightaware.com/live/flight/JAL6/history/20230105/02...
The Japan to Europe flights are even worse. The great circle route cuts west, straight across Russia [0]. These days, they fly east to the Bering Strait then more or less directly over the north pole [1] (though probably easier to see on great-circle: [2])
[0] http://www.gcmap.com/mapui?P=HND-FRA
[1] https://flightaware.com/live/flight/DLH717/history/20230109/...
Back in the Soviet era when USSR airspace was closed to most Western flights, planes couldn't do that route non stop from Europe, so had to stop over in Anchorage for refueling.
http://www.gcmap.com/mapui?P=BINP%2CFRA-KUTAL%0D%0A&MS=wls&D...
Need to find an excuse to go to Japan
Playing around, a theoretical NUE (Nuremberg) to KUTAL flight comes within 1 mile of the North Pole
Well into the 24 hour polar night/day period though (depending on time of year)