On the private side, before the Russian invasion of Ukraine, we routinely would use Petropavlovsk on the Kamchatka Peninsula and Magadan for fuel stops to/from Japan and deeper Asia. Routing would usually be ANC-ADK-PKC-CTS- Asian destination. Some aircraft could overfly a stop if the winds were right.

And, back when AS (or maybe just armchair CEOs on FT) was contemplating flying to Japan with their 737s, Siberia was a part of the discussion.

But, here we're talking about the reverse direction (aided by strong jetstreams that almost never point anywhere close to NNE) on planes that can fly halfway around the world without needing to refuel.

I’m pretty sure I remember doing it many years ago in JFK-NRT. I flew that route a number of times and on this one we went almost due north out of JFK to just south of the North Pole then down into Siberia and turned east to NRT. I think the pilot even commented on the unusual flight path that trip.

JFK-NRT goes TO Japan from the US, and indeed can benefit from polar routes when the jetstream over the Pacific is dialed up. But, the reverse direction is what we've been discussing here.

Sorry I didn’t notice that implied directionality.

On the subject of ETOPS distances, I was on an LHR-JFK flight where while on the ground at LHR (out taxiing around) we pulled over and stopped and the pilot told us they had a mechanical issue with the air conditioning. After a while the pilot came back on amd said they checked the manuals for the aircraft and we could do the flight on the backup but it changed our ETOPS rating so we had to do a reroute. We went north over Scotland, then over to Iceland and then over to northern Canada and roughly followed the St. Lawrence River for a bit. I think we came back into the US near Montreal.

That’s the route for FRA to DFW which goes south of Iceland and over Greenland.

this was probably an ETOPS-120 track, as opposed to ETOPS-180 for either more northerly (likely shorter distance) or more southerly (likely better winds, so shorter flight time)

ETOPS-xxx identifies the number of minutes to the nearest suitable airport after an engine failure