I've been sitting here firing arrows at this dragon for 5 minutes now, and it just won't come down... I'm not even sure if I'm hitting it, but I can't seem to aggro it. How the f**k are you supposed to get the f*ckers down!?

Sometimes dragons spend like a few minutes just flying around you and other times they have just flung in from behind a mountain and really surprised me. Destruction magic has worked well for me so far.

Ahem well, there is another possibility.