Originally Posted by
ATC Watcher
I am not sure any of the 2 aircraft involved were equipped with ADS-B out , more likely the data you are talking about comes from F24 , and the data then coms from the transponders relayed via a few private antennas on the ground. It is not the certified ADS-B we talk about in ATC or Commerciall aviation.
As to using the vertical rates mentioined earlier , I persoally doubt the calculations and the figures posted . , FR24 is a great tool but is not exact science
You are referring to the MLAT feature used by FR24 for non-ADS-B equipped a/c, but this does not work for a/c at low level and is always too inaccurate for tracking a/c maneuvering sharply
And the Youtube clip from post #236 clearly shows ADS-B / UAT as Signal Source.