I have researched myself to death on this one and cannot find a solid answer. I am thinking it is due to the GPS not having acquired its position fully, but here is what I am facing.
I power up the Pixhawk and let it go through initialization. I arm the Pixhawk and then arm via radio. My radio is setup to always startup in Loiter mode. When I do this, I get a loud beep...beep...beep...beep that does not stop unless I disarm or go to Stabilize mode. The copter will arm but it continues to give me this noise. I have a blue "breathing" LED until I arm at which time I get the green.
Any knowledge that can be shared about this is greatly welcomed!