Auto take off and crash


Recently I had a strange crash which I couldn’t understand. I had a quad and it operate normal when I manually take off (manual mode) and then switch to position mode, the quad can hold its position well (with good GPS lock). Then I tried to use QGC to command the drone take off using the build in “take off” button, the quad take off and reach its take off altitude, then suddenly, the quad start drifting while drop altitude, in the end it smash into the ground.

Here is the log

After reviewing the log, I couldn’t find a reason why it acted like this, could any one help?


according to your log the navigation filter (EKF) got very unhappy. Maybe vibration or bad sensor calibration or something else.

this looks like bad vibration all over the place:

this indicates the EKF being super unhappy:

these messages also indicate the failure:

Hi Antiheavy,

Thanks for the help. Do you think the “no global position”/“no local position” happened because of a GPS failure?


I don’t think you had a GPS failure. The GPS looks fine (up until the crash). It’s all the other sensors that seem very unhappy, maybe due to vibration? The way EKF2 works is that even though GPS might be totally fine, if the other sensors disagree wildly then EKF2 will not output a position solution.

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