The chart posted looks to be from the ADS-B data posted by
FlightRadar24. You'll note that the last data recorded on the chart is 8:37:43; when the FR data resumes, 30 seconds later, the aircraft is stationary, and the altitude is still fluctuating between 525/550 (Q0994=530 feet, 0993=546).
The first time they get to Pressure altitude
2016-08-03 08:37:13Z.302,0x89609b,UAE521,25.26224,55.35482,525,4772,177 ,122,-448,A
Or 177 kts
The low point on the chart comes eleven seconds later:
2016-08-03 08:37:24Z.872,0x89609b,UAE521,25.25739,55.36341,475,4772,154 ,122,512,A
Or 50 feet below pressure altitude, 154 knots and climbing.
The bounce peak is:
2016-08-03 08:37:35Z.134,0x89609b,UAE521,25.25423,55.36921,625,4772,134 ,120,640,A
100 feet above pressure altitude, 134 knots. They don't get any higher, and the speed comes off.
This is probably when they hit:
2016-08-03 08:37:40Z.160,0x89609b,UAE521,25.25249,55.37249,525,4772,124 ,119,-1024,A
First, these data are obviously suspect. ADS-B is not an accident investigation tool, and that there's a reading 50 feet below pressure altitude doesn't help.
Second, if you believe the data, they came in, floated for eleven seconds, then pulled up, bled off their remaining airspeed and came down again when the thing stopped flying.
Third, don't believe everything you read on the internet.