Unhealthy AHRS, Need position estimate

Hi Team,
I have been facing the isse when I try to arm the copter in loiter mode. I have connected my GPS and led is green when it is in stablize mode. WHen I hcange the mode to loiter it changes to yellow and get error in the screen PreArm need position estimate. I have done the calibration couple of time and checked wiring. everything seems to be good. Not sure what the error is. Any help on this please ?

  • Loiter requires “GPS Lock”
  • Stabalize does not require “GPS Lock”

If you want to take-off in loiter you need to wait until you get a GPS lock.

Hi lucas,
Yes. For stablize mode we dont need GPS. Im able to arm and lift in stblize and altitude mode.
I could see good GPS signal and my location in map too. I see led glows green which indicates good gps signal.
But problem comes only when i change to loiter, guided mode. Led also change its status to yellow. I waited for a long to see if it awaits for gps lock. The erro also indicates pre arm need position estimate. Is tht a problm with hardware and GPS or firmware???

Provide a .bin log where this is happening and we’ll be able to help.
If you are going to run missions and use guided mode it will be best to set FENCE_ENABLE,1 and WAIT…
You can not arm in any mode until there is a good 3D fix and Home position has been set, not even Stabilise.

It can take a while, but then you know for sure that Home is set. This gives you a good opportunity to stand around and review the planned flight and think if you’ve missed any pre-flight checks.
Check that the other Fence parameters are appropriate for you.


Hi shawn,
Thanks for the help. That solved my problem. I have enabled fence and the error " need position estimate" is gone.

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