Hi,
We were flying our 2 weeks old Mavic 3 Pro Cine yesterday in waypoint hyperlaps mode over water around some marine construction activity.  Around 10 minutes into the flight, the drone dramatically started to lose height and very nearly went into the sea.  We stopped it just in time by cancelling the flight and flying it back.  We then conduicted a second flight in free hyperlapse mode from what we wanted to be a fixed position.  However, the drone continually lost or gained a significant amount of height.  We manually controlled it but the resulting hyperlapse is not useable due to significant movement.  

The really odd thing is that the height reading started at -1.7m (we are flying from a platform c 40m above the water) and by the end of the flight the height was showing as c-75m inspite of the fact that we had controlled the drone to try to maintain the height.  In reality it probably varied by c5m.  

Wind was at c8m/s so challenging but within limits.

I'm sure you can approeciate how alarming this is!  Any thoughts before I send it back would be approeciated,
Regards
Richard

Hi there, please note that the aircraft flies by visual positioning. Be careful to avoid areas with specular reflection such as water or snow. We recommend that you not fly the aircraft close to the water, as flying on the water surface will affect the normal function of visual positioning, and the aircraft may fall into the water due to the impact on positioning accuracy. You can also refer to: https://dl.djicdn.com/downloads/ ... _User_Manual_EN.pdf

Thanks for the reply but that's not the best news.  So it uses visual positioning, even at c30m, and it's ineffective enough that we can't trust it over water?   Can we expect it to lose or gain altitude in normal flight as well?  I believed they use it when GPS is not available not when GPS is VERY available.  How does that explain the wildly inaccurate height telemetry?