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.
I do think, this is just Mode-C/Mode-S, using MLat to get the added details. Although MLat is "declared" to be only useful above 3000ft, it highly depends on the number of receivers with proper sky-view in that area. Given the trajectories and other parameters are not really looking ragged, I think, the accuracy of the (playback !) flight paths in the YT video is pretty good. Not to say, the collision location fits quite good with the factual wreckage location(s).
For real-time professional use, the "FR24" is not that suitable, insufficiently calibrated, unreliable, etc.
Though for replay, with the opportunity to remove obviously wrong data points, recalibrate, etc, this data is also used by the national safety boards to analyze the happenings.
Originally Posted by
Locked door
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
I think, on the contrary. FR24 is an excellent data source to retrieve otherwise lost data. Of course, one needs to calibrate this data against other known sources.
The simple fact, none of the relevant parameters for this accident does show ragged playback, suggests, the data is pretty reliable. When you calculate a vs from subsequent altitude data points, and the vs does not show jumpy values, it is reasonable to assume, the altitude data points are reliable and accurate (in a row, of course, needing calibration).
Of course, it could be, the static pressure system / Mode-C measuring of the P-63 is completely off calibration, though for that, check the earlier circuits of the P-63 in the same display. I didn't, though, feel free to do so and report back. I have no reasons to assume, the final 30 seconds of data points would show erroneous, whereas the earlier ones would be OK. FR24 gives really powerful data, provided you know what you do.