As I mentioned the incident occurs when there is a difference in GPS derived velocity and IMU derived velocity. I noticed that these differences seem to be correlated with abrupt pitch changes. The latest flight looks like this
The top plot has the north velocity difference (blue) and the east (red) velocity difference. Pitch (blue) is shown in the bottom plot. Also included are the Y axis gyro data (green). I suspect the .DAT from the Spark itself will reveal a more pronounced correlation between the Y axis gyro data and the velocity differences.
These pitch changes were not the result of elevator inputs. Probably due to gusty wind conditions - although they seem to be a little abrupt. The AC .DAT would tell us more.
Your previous flight has pretty much the same phenomena.
What’s all this mean? I’d be interested to know if you’ve done an IMU calibration. Especially since the previous flight 10-15-2018. And, can you do an IMU calibration followed by a test flight then provide the .DAT for that flight. During the flight try giving it full forward elevator and once max speed is obtained give it full back elevator. This should result in some abrupt pitch changes.