Originally Posted by
jimjim1
I then tried the flight number CX890 as the call sign as a FR24 filter - no good.
I don't see why that wouldn't work. A Google search for FR24 CX890 finds the flight history as the first hit.
Incidentally, a Google search for
"flights from [departure airport code or name] to [arrival airport ditto]" (omitting the brackets) will tell you which carriers fly any route, and you can easily drill down to find the flight numbers concerned.