Oh shit moment. Copter rises without any throttle input

I manage to arm and spin the motors and started the flight. But the more I discover things, the more conscious I become on what untoward incident the copter does so my finger is always at the Emergency Stop switch just in case. And I was right, without putting any throttle input, the copter started to rise. Oh shit comes into my mind and scared of loosing the copter, I immediately turned on Motor Emergency stop. Copter dropped straight to the ground but undamaged. Thank God.

When I investigated the log here’s what I found.

If that was an RTL, what could have cause it?

An onboard log would confirm the issue but in short the “Vibration compensation ON” means that the vehicle is experiencing very high vibration. When the IMU saturates the EKF is unable to correctly calculate its climb rate and it can lose altitude control and normally this means it shoots up into the air. The vibration compensation will take over and bring it down but it can takes a few seconds for that to happen.

Please check out the wiki page on measuring vibration and vibration isolation.

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Hi @rmackay9,

Thanks for the analysis. I will check the links you provided.

Here’s the graphs for the vibrations. There is a sudden spike when I did a U-turn and that’s when it started to rise and I panic. Green is VibeY. But the spike is X, Y, and Z.



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That all happened after the fact. You have the GCS failsafe set to RTL and that’s what it did. Until you panicked and hit the E-stop that is. You should consider the FS_OPTIONS parameter. 16 may be a good choice…

Thanks, I will set it to 16. I really don’t care if I loose GCS while I am in control from the radio. This Firmware is really good but with so many features that its hard to coordinate all parameters. Part of the learning curve. I’m loving it but getting more scared of it.

Do extensive failsafe testing, gain confidence in the Autopilot’s ability and then trust it.

And review the other FS Options and think thru what makes the most sense for how you fly.

Do you have telemetry on your transmitter?

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Yes I have telemetry and Yappu. the tele items are a lot.

But I cannot make Yappu work. The radio is a TS16S running on EdgeTx

Have you selected CRSF in the yaapu settings menu on the radio?

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Yes I did. Here’s the crossfire and radio settings

Nope, That’s for the Crossfire module. I’m talking about the yaapu menu.

Hold down the SYS button on your radio and go to the scripts menu. There should be one called Yaapu Config, select that one. In there you’ll see an option for CRSF telemetry. Make sure that’s turned on.

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Horayyy… That’s it. CRSF is not ON in Yappu. Now I have Yappu. How convinent now. Thank you very much.

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Yappu is a big upgrade to my Copter. Messages are at the bottom and in Page 2 so I don’t have to go in front of my PC to look for the messages anymore. Really appreciate your help.


Right, that’s why I asked. You have the info in your hand to make an informed flight decision. Consider disabling the GCS FS.

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Thanks a lot. When I was first reading the FS_OPTIONS parameter, it does not make sense to me. I was asking myself, what a hell does this do? I should have asked that time but don’t even know what to ask.

But after this incident, then it made that parameter very sensible. Every day I learn and getting more confidence. I still have a lot of questions in my mind, but I will deal with it slowly. This is really overwhelming for a beginner like me. Thanks for all your help guys. You’ve done a fantastic job on this firmware.

If you can step back a bit, I’ll make a suggestion. For a first flight of any sort with a new controller, aircraft, radio, and software eco system, there’s a lot that needs to be right to avoid disaster. I’d tie the aircraft down to something and verify throttle and the ability to control pitch and yaw at the most basic level before letting it go free.

Yup I did that on my maiden flight and some succeeding flights until I get a bit of confidence that the copter is able to level straight. One brick per leg with a very sturdy rope cause I was so worried it might tip over if I only use one rope.

When the Oh shit moment happen, my copter has at least 30 flights already. But yes I’ve already learned my lesson. The most dangerous part is during tunning I guess as you are changing PIDS that might end up in a flyaway. During this step, tie your copter again. Sounds funny but will save your day if something goes wrong. No joke.

That’s not a good idea. The PID control loop is expecting certain reactions and movements and if you tie down the drone it can cause the I-term to “wind up” resulting in a more dangerous situation. Test your motors using mission planner. Follow the tuning instructions. Set up, test, and be ready to use the an arming switch, or emergency motor-stop switch.


Thanks. I didn’t know that.

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