VTOL starts climbing 8m/s instead of landing at -1.5m/s


I almost crashed the drone. I need help to prevent such problem in future.

At final stage of mission VTOL starts climbing super aggressively at vertical speed 8 m/s instead of landing.

I tried to change to QHover and QLoiter modes without any results. It didn’t respond to throttle stick. Only switching to QStabilize allowed to control altitude at 400meters and I land it without crash.


I checked logs and the only problem that I could see is difference in QTUN.Crt and QTUN.DCrt.

I’ve made a error and positioned the last waypoint too close to VTOL land. It forced the drone to make super aggressive braking. Maybe it caused the problem. Do you have any advise what is best practice for VTOL Land planning? What is safe distance for transition?

One more strange behavior at start. At the end of Quad > Fixed Wing transition it got internal error 0x400 and some strange Failsafe that I can’t find in the dataflash logs. It is available only in telemetry logs. It also pushed the motors hard at that point. After that it was always FAILSAFE and internal error 0x400 blinking on the screen.

FAILSAFE and 0x400

Motors high at the end of transition

Dataflash and telemetry logs are available at

Thank you for help

Do you check vibration levels?

Yes, vibration level is not high. For FW flight it almost zero. I was getting internal error whole flight.

An year has passed so… have you found the root of the problem for the fast climbing? I’m having the same issue right now.

I haven’t found the problem. It didn’t reproduce anymore. But I’m always ready to move to Stabilize.

Thanks for the quick answer! Guess that’s a matter of distance to the landing point and excessive flight speed that leads the airbrake to be too aggressive and climb upwards, then. I’ll try to take that in consideration during future flights.