No, for flying there is a quasi-facing system. There's minimum forward speed and limits on how much you can turn per x feet moved. If you moved 50 ft east last round and have clumsy flight, you can't just start flying west at the start of your next turn. That's why there are entries for turning...
The dragon's easy flight bothers me a lot, too. Not only the grace it seems to possess, but also how you say you can't follow too easily because of sight limits in the dark. Unless the dragon knows the area it's flying in VERY well, how the heck is it plunging forward at 200+ ft in a 6 second round completely confident it won't be smashing its face into a rock wall? I mean, check out the
Hampered Movement rules. Moving in poor visibility typically cuts movement in half. So how is the dragon sailing ahead into pitch darkness like that?
I think your DM is intentionally or unintentionally cheating. And please don't tell me DM's can't cheat. *sigh*