Well it turns out neither of them at all accurate.

I last checked the websites at 10 minutes before the scheduled landing time;

- The airport said it was landing 5 minutes early.

- Qatar Airways said it was landing 5 minutes late.

Close enough not to worry about. So I went to the airport and ended up having to wait around because it actually landed 25 minutes late. Granted that's not a huge difference, but I'm surprised they can't be more accurate.

So SAMAEL, obviously the airports control tower isn't very good at tracking. That's a little worrying.

And stealth, as the flight took off exactly on time it seems that your theory of using that to predict the landing time doesn't work.