According to this, it fell below ground level! And fortunately it was still transmitting after crashing so I have the GPS coordinates of its resting place. If I can just get through the stickers…
The altitude isn’t always reported correctly after a drone crashes.
Your flight log shows exactly what you described. I see nothing that explains the sudden uncontrolled descent. Contact DJI support and see what they say. Based on the data in the flight log, they might offer to replace it even if you aren’t able to retrieve it.
Very pleasant exchange of emails with Alvin at DJI support. After verifying the serial number (glad I kept the box) and the purchase date (less than a year old), I was asked to sync my Go4 app to their server to get the flight log. He asked for my shipping address, date & time of the incident, RC serial number and a description of my actions during the incident. Today I was assigned a case number and told "We will send you an update on the status of the case and result of the analysis as soon as it becomes available. " Excellent CS.
Today I received an email from ‘Lydia’ at DJI Tech Support which said:
Thanks for your patience.
The unfortunate incident that occurred to your aircraft has been confirmed as a warranty case according to our data analysis.
We would like to offer you a replacement, Spark (Alpine white) without the remote controller. Please kindly send us the following information:
I’m impressed. And pleased.
FINAL UPDATE: Replacement Spark, battery and props sent UPS 9/13, arrived today. Relinked the RC, updated firmware and flew for an hour! Great customer service.