Copter became hardly controllable and crashed; Log indicates a fail to enter the flight mode (AltHold)

I tested my Copter (Navio+ board from Emlid and RPi2). The copter was started in Stabilize and later I switched to AltHold. From there the copter behaved weird. It was hardly controllable, went up and down in altitude and crashed.
Then I launched again from Stabilize and the copter was going down on the field a little bit later again. It was simply hard to control the device.
The copter was able to fly well. I just repaired it from an earlier crash due to mechanical problems and changed to the latest Navio2 image from Emlid. According to the log, I cannot find a reason for the issues.

Btw: The file upload is broken, it complains the file would be too big, but it isn’t

Tested again and triggered this time the battery fail-safe. The copter tilted in the air when the firmware switched to RTL. Loiter does not cause a flip?!


Thanks for the testing and report.

The issue is probably related to the fact that the vehicle was flying before the EKF had a good position estimate. This caused it to fail to enter Loiter mode but more importantly you may have uncovered an issue with AltHold before we get the position estimate. I’ll check into this.

For now, I think it would be good to wait for a good position estimate before taking off which you can do by switching into Loiter mode (before takeoff) and waiting for the LEDs to become green. While you’re in stabilize mode (on the ground) the light will become flashing green but that actually doesn’t mean that it has a good position estimate yet, it only means that it has a good GPS lock. I think maybe we should change this so that it only goes green once it has the good position estimate. That would make it consistent with the autonomous flight modes. I’ll discuss with the other devs.

By the way, looks like you’re flying -rc1. It would be great to upgrade to -rc2. I’m not sure if you have to wait for the emlid guys to produce a new binary or if you can just get it from the site.