Hi and apologies if this question has already been asked a million times!
Who actually assigns call signs to each individual flight ? Is it the airline or the aviation authority of the country the airline is from ?
It would cause a lot less confusion if they were the same. For instance. British Airways flight BA2159 LGW-UVF has the call sign BAW9VA, but you won`t find that flight on this website as it is shown as BAW2159.