I've seen them on a flight before quite some distance from the north pole. I am not 100% certain on the flight but I think it was a Norwegian Air Dreamliner flight from London to New York, which still goes reasonably far north.
We had a spectacular view of them a few years ago on a flight from Portland (OR) to London.
Even the regular not-quite-north-pole-but-over-65-north are more than good enough. In fact, since the aurora is an oval, it's better to be a bit further south than at the pole. Not sure which the best latitude is, but guessing it's arund 70 north or so.
I’ve once had an amazing view on the northern lights flying icelandair. Crew went around waking people up so they could see it.
I've seen them flying from Minneapolis to Bismarck, ND. I could also see them from the ground in North Dakota, albeit a bit weak.
United forced the window shades closed on the 787 trips I took over the arctic circle. Couldn’t even see them if you wanted to.
Peak aurora season is during and after the polar night in Dec to Mar. If the shades were forced closed, your flight was likely during the Midnight Sun period of 24h light, meaning you wouldn't have been able to see them anyway.
I hate that the 787's electrically dimmable windows can be centrally controlled! Yeah it makes sense that they are "locked open" during takeoffs and landings, but horrific when you want to look outside to see the stars and the coffee-cart pushers have locked them for the night.
I'm sure it's not only United, but keeping the windows dimmed the entire flight seems to me more like reducing the workload of flight attendants (making everybody sleep more) on ultra-long hauls so they can spend more time in the back gossiping back whatever they like to gossip about.