I know FlightAware and actually all the real time flight tracking services that I’ve come across are unable to track international flights. Does anyone know of a website that does? I have a friend who flies from the UK all over the place A LOT, and I’ve been unable to find anything. Help??? Thanks so very much in advance.
Welcome to the forum flyawa! Great to have you here! 
Please search the forums and you’ll find the answer to your question most of the time. I found THIS thread when I searched for “international tracking” on the second page. Please read it.
As for an internet site like FA that tracks Europe flights, it doesn’t exist (at all). Your best shot at tracking your friend’s flights would be directly from the airline or its website (i.e. THIS and THAT). (I couldn’t find one for British Airways or I would have posted it.)
Thanks very much for your responses. It was pretty much as I surmised. Appreciate your taking the time, tho. Enjoy your Sunday!!!