Originally Posted by The Ancient Geek
1) It is foolish to rely on FR24, the sytem works by collecting data over the internet from amatuer ADSB receivers owned by enthusiasts and joining the dots. There are plenty of these stations in well populated areas but the chances of any reliable receiver data in the middle of an enormous desert are a tad slim. In these circumstances FR24 extrapolates (guesses) by extending the last known trajectory until it recieves a valid report or times out.
It is therefore not possible to derive a rate of decent from the last guessed postion and a single and possibly unreliable following report.
What a load of BS. You clearly have absolutely no understanding how the system works.
The only instance where FR24 extrapolates the data is if you have the option active in your browser, it will do so for you, but that's it.
The data they posted is the data one or more of their receivers received. It's the RAW data, as broadcasted by the airplane.
If there is an error in the data, it's because the airplane was broadcasting erroneous data, not because FR24 extrapolated anything.