On a recent Sentinel Drone test flight, the compass heading switched 180 degrees while in flight. All preflight checks were accomplished without any errors being detected. Approximately 2 and a half minutes into flight, the drone began an uncommanded right-hand turn. The drone was sent an RTL message, which it reported as received, but it did not respond. the drone continued to turn right at a faster rate and crashed. Review of the error logs after the crash showed that the drone yaw orientation prior to the error was =83 degrees. the Yaw after the error was a negative 89 degrees (-89 degrees). The logs indicated there were multiple compass errors requiring a calibration in mid-flight. the error messages were two "compass needs calibration - land now", followed by two "GPS spoofing detected", and then followed by two more "compass nees calibration - land now" messages. The elapsed time from the first message to the last message was 8 seconds. None of these messages were transmitted to the ground station and were found during the post-crash investigation.

Additional Information: The drone was a VTOL sUAS ModalAI Sentinel Drone utilizing a Remote Control Spektrum DSMX Reciever 2.4GHZ, WiFi Short Range IP Conectivity for nearby flights and a 5G LTE Longe Range BLOS capability. Navigation Sources were the Ublox Neo-M8N module GP. Navigation modes included Fail Safe Mode Px4 Safety Configuration and Manual Remote Control.

Any thoughts on what would have caused the compass to flip 180 degrees in flight and steps to take to prevent this from happening again? Have any other users reported this type of error?

We have a ModalAI Sentinel drone that was airborne approximately 2.5 minutes, when the Yaw orientation went from +83 degrees to -89 degrees instantaneously. The aircraft started to veer right, and we applied left input to straighten it out. The more left input we gave it caused it to turn right faster and it crashed inside of 10 seconds. Once we were able to download and read the logs, it recorded "compass needs calibration - land now" twice, followed by "GPS spoofing detected" twice, then the "compass needs calibration - land now" message two more times before crashing. Those messages were not transmitted to the ground control station. A RTL message was sent to and acknowledged by the drone, but that message was disregarded. We confirmed that there was no other activity on the range when this happened, so we are confident that no GPS spoofing was occurring.

Have any other users reported any incidents involving a compass error like what we encountered. Are there any procedures, or software changes that we could initiate to ensure that this is not repeated?

Additional information: Datalinks: Remote Control Spektrum DSMX Receiver 2.4GHZ, Navigation Sources Ublox Neo-M8N module GPS, and Navigation Modes include Fail Safe Mode Px4 Safety Configuration