This might have helped but....
Might not be news to others but I only recently discovered that if you run LiveATC with Flightradar you can see approximately where the transmissions to and from the aircraft are made. Tried the same thing with archived outputs including 521 crash only to find that Flightradar plays back at X 12 so cannot be matched to ATC. If anyone else wants to investigate further, today is probably the last day you can replay 3rd august on Flightradar.