Y6B sudden high-velocity toilet bowl in Auto

Last week I flew my 3DR Y6B in Auto and nearly lost it. After about a minute into the mission it began deviating from the waypoint course, and started a large toilet bowl pattern. Switching to RTL did not remedy the issue so I had to take control in Stabilize and fly it home.

No hardware changes were made prior to the flight, and the firmware was updated to the current version two flights earlier. I’m not sure where to look for the bug, anyone have any ideas? flog is attached.

Also, this is using an APM 2.6, the 3DR Y6B motor configuration, and 880kv motors. 3DR GPS on a mast. Other than that there have been no hardware modifications.

Hello all, somewhat new to Quads. I recently have started trying to do Auto Missions using GPS and Mission Planner. Things have been working good and as I would expect. But the last flight almost went bad.

I had flown several Auto Missions during that flight, maybe 6 or 7 and everything was going good. I started to manually fly it further and further from home and then engage Auto. Well the last one, at about 15 minutes, did not return or try to go to the first WP. It was quite far away, and I couldn’t quite tell what it was doing, I let it do it’s thing for maybe 30 seconds and decided I should go back to manual (stab) and try to get it back. I got it back. I did not think to try RTL at that point.

The modes I have set up are Stab, then RTL then Auto.

When I look at the log file, at around 15 minutes (after 6 or 7 successful Auto flights on the same flight) I again engaged Auto and according to the GPS (in Google Earth) it started to circle in an increasing radius spiral at a roughly constant altitude. Sort of like a rabbit looking for home! Haha. I don’t know if that is a “toilet bowl” or not. It looked like a perfect increasing spiral to me.

Any ideas what I should be looking for in the log file to figure out what happened? Could there be a bug that shows up after 6 or 7 Auto flights in the same flight?

log attached.

Oh, HKPilot Mega V2.5, Ublox LEA-6H, Multistar 4225-610kv, Qbrain 4x25, custom quad frame about 700mm across motor to motor, 12x47 plastic props, 4200 3S battery. No video or other transmitting devices on board. Futaba 10GC radio, 7 channel rx. Mission Planner 3.1.4.


This sounds just like what happened to me. Hoping one of the developers can compare our logs and find a common thread…

I did notice in the cmd part of the log that right at the 15:xx time when I did the last auto, terms like cnum and others seem to be missing, or go blank or stopped recording or something. So it’s like I put it in Auto, yet there were no commands to do.

Maybe some kind of memory overwrite or bug or something after so many auto flights in the same flight screwed up a memory location?