Originally Posted by
ATC Watcher
With a mode S return you can very accurately calculate the ground speed and the final rate of decent
I'm still struggling to understand how that can be so. Can you explain further ?
You said previously that you were talking about Mode S and not ADS-B, but basic Mode S only gives you surveillance ID (squawk) and altitude (DF5 and DF4, respectively).
So, yes, you can calculate RoD, but the download data contains no velocity information so I don't see how it's possible to derive GS.
Originally Posted by
ATC Watcher
I noticed the BEA said it will be concentrating the research within 4 square miles, so here you go.
No doubt that's true, but the estimate of final position could well have come from primary radar (possibly military?), rather than SSR.