Pixhawk Power Failure, What Happens?

Question: What happens when the Pixhawk loses power during flight?

I recently suffered minor damage in a crash when I lost control over my hexa. I was about 10ft away from the hexa at takeoff and lost control when it was probably 25ft away. I know the receiver/transmitter is a possible culprit, but I did notice the power cable going to my Pixhawk was disconnected at the crash site. Did it come loose during the crash or before, I don’t know. What I’d like to find out is what is the expected behavior when you are mid-flight and the Pixhawk goes dark. Will the motors keep turning in the event the Pixhawk goes dark, or will they pretty much come to a stop in that sort of situation? Either way, I’m starting to look at adding another power source before I repair and attempt to fly again.

Pixhawk Flight Controller
SunnySky 380kv motors
30A Opto ESC’s
13" x 5.5 Carbon Fiber Props
6000mah 6S Lipo (Turnigy)
FrSky Taranis X9D Plus Tx
FrSky X8R Rx


If the pixhawk loses power the esc’s have no signal to tell them to spin the motors, the motors stop and the uav comes down…quickly.

Thanks, Mark. That makes sense.

I took a few months break from this hobby, but I’m getting back into it now. Given what I saw (when I lost control of the hexa) and the fact that I had recently changed out the radio system (went from Spektrum DX6i to Taranis X9D Plus), all my money is riding on radio trouble. I don’t recall the Taranis saying it lost link at any point, but the panic of losing control over a bird you’ve put over a grand into may have drowned out anything it tried to warn me about. :slight_smile:

To cover my bases, I decided to add a second power source to the Pixhawk as well as enabling geofence and radio failsafe. In addition, I’ve ran some extensive range checks to make sure the radio link is solid. Looking forward to attempting another flight this weekend now.