Why are my friends flying over Norway, Sweden and Denmark from Manchester to Vancouver?
(gcmap.com)

Above is the shortest route, it's called a great circle route. This is what airlines try to follow as much as possible.

The possibilities:


They've mistaken the icy parts of Greenland and northern Canada for the Scandinavian countries1
They've mistaken the western Scottish fjords for Scandinavian fjords
They need new maps :)




On a great circle route, like a taut thread over a ball, the bearing changes. Roughly it'll be something like this:

Initial heading of NW for 1,000 nautical miles, WNW for another 1,000, then West for 2,700. That's a very rough visualization, because again along the route the heading changes, just like the thread.

The route takes you along the western coast of Scotland, across the Atlantic, passing over Iceland, then Greenland, then Canada, where Vancouver is.



1 Denmark, Norway, and Sweden compose Scandinavia according to the normal definition.