Originally Posted by
emcampbe
3648 doesn't sound like a flight number for a regular AC-operated flight. Today's YUL-FRA is AC 874. Are you sure it was a 3xxx, and if so, wasn't an AC flight operated by LH? That may not even make sense - just typed in a bunch of random 3xxx numbers and seems to all be UA (express) flights.
3648 is the great circle distance in miles between yul and fra.