Physicus - your ADSB data doesn't seem accurate
UTC Time +/- 10s: 2019-09-06 08:14:17: TRK: 48.0 GSP: 127.0 ALT: 1450.0 V/S: -9024.0
UTC Time +/- 10s: 2019-09-06 08:14:07: TRK: 48.0 GSP: 127.0 ALT: 1450.0 V/S: -9024.0
UTC Time +/- 10s: 2019-09-06 08:13:57: TRK: 48.0 GSP: 127.0 ALT: 1450.0 V/S: -9024.0
UTC Time +/- 10s: 2019-09-06 08:13:47: TRK: 48.0 GSP: 127.0 ALT: 1450.0 V/S: -9024.0
UTC Time +/- 10s: 2019-09-06 08:13:37: TRK: 121.0 GSP: 152.0 ALT: 2200.0 V/S: -8768.0
UTC Time +/- 10s: 2019-09-06 08:13:27: TRK: 121.0 GSP: 152.0 ALT: 2200.0 V/S: -8768.0
UTC Time +/- 10s: 2019-09-06 08:13:17: TRK: 121.0 GSP: 152.0 ALT: 2200.0 V/S: -8768.0
In several places the Alt reading remains the same for 3 or 4 readings in a row whilst the VS is off the clock - they can't both be right so I wouldn't read too much into them other than a 9000'/min RoD is not indicative of a controlled situation, as others have said