Flashing Blue Lights after 3.6 update

Hey Everyone!

Running a Pixhawk (cube) with a Here+ GPS unit. Just updated from 3.5 to 3.6. The first time I went to go flying with it after the firmware update I noticed I wasn’t getting flashing green lights. It was just flashing blue… so I waited for like five minutes. Still flashing blue. I thought it was odd it was taking that long to get a GPS lock so I checked my ground station. Via MavLink Mission Planner indicated a 3D Fix.

I thought it was strange that I was seeing blue flashing lights (indicating no GPS lock) while Mission Planner was showing a GPS lock. So I picked up my controller and armed the system. Once the armed the system I got a steady GREEN light (I would have anticipated a steady BLUE light). I disarmed the system, it went back to flashing blue. I armed again, and back to steady green.

Is this odd behavior? My understanding is that flashing blue lights indicates a disarmed state with no GPS lock. However, a steady green light indicates an armed state WITH GPS lock. Am I crazy?


I probably should have made the initial question more concise.

Revised question: Is it normal to have blue flashing lights (pixhawk cube, here+ gps) when Mission Planner indicates a “3D Fix”?

Thanks again!


edit: well i guess you figured out the meaning of the lights… ya i’m not sure about that either

Appreciate the response!

Yeah, I can’t seem to understand why:

  1. I can no longer get flashing green.
  2. I get flashing blue when my ground station indicates a GPS lock.
  3. When I arm the system it goes from flashing blue to steady green. When I disarm the system is goes from steady green to flashing blue.

I suppose I could just revert back to the old firmware.

Hello Tyler,

We had this same ‘problem’ from 3.4.6 onwards.
I can’t quite remember the solution for this but I will check with my colleagues tomorrow.
It had something to do with pre-arm checks.


Hey Toni!

Really appreciate the feedback. As far as the flying goes, it behaves normally. Just stuck me as kinda odd. Glad to hear I’m not the only one affected :slight_smile:


Hello Tyler,

Sorry for delayed reply.

Have a look at your parameter ARMING_CHECK .
We found that enabling GPS lock in the parameter ARMING_CHECK resulted ‘normal’ behaviour of the leds.
Now the led shoud flash green when gps lock is achieved.

We also had another mysterious problem with flashing blue/red leds. It occured maybe 1 out of 50 flights and always at power-on or reboot.

The problem was following: the ESC’s would keep on beeping and the GPS leds kept flashing blue/red. No error messages in MP. Arming the copter (via rc transmitter) would clear the problem most of the times but not always.

The reason was too ‘tight’ RC-calibration. AC was sensing that the throttle was not completely down and thus interrupting it’s regular boot routine. Therefore there was no pwm sent to esc’s and they kept on beeping. By arming (via rc transmitter) , the pilot pushed the stick downwards causing throttle channel pwm to drop few microseconds (just enought for the autopilot to be happy) and clear the problem.

The cure was to calibrate the throttle channel so that one would leave one ‘click’ of room in the downwards position of the stick.


SUPER HELPFUL! Thank you so much! Really appreciate it.



I’ve got the same problem after upgrading t o3.6.1.1 My LED blinks blue. When I enable “all” safety checks, it still blinks blue. When I only have the hardware switch check enabled, the Pixhaw led blinks yellow until I depress the arming switch, and then it blinks green. Any explanations?

I’ve managed to partially fix this. I remembered this happened on my other Pixhawk1 and the way I fixed it there was to arm the craft with the hardware switch safety check aneable. Then unplug the safety switch from the Pixhawk, disconnect from Mission Planner, and reboot the Pixhawk. Now I get the blinking green light, and when I go to arm it, no change. Don’t know why it won’t arm with ALL safety checks disabled now. Reasons to try?