We have a lot of PixHawks flying both copter and planes, so you have a lot to choose 
You have to remember that EMI from your set-up is going to be higher when youâre in the air than on the ground. Because it is current-dependent.
So the fact that you have GPS lock on the ground and are able to arm is no guarantee you will keep GPS lock in the air.
And if you lose GPS lock, anything can happen if RTL is triggered. If the flight controller knows where home is, but doesnât know where the drone is - trouble.
So I wouldnât personally test RTL on the first flight of a brand new set-up, until I had flight logs and could see there were no GPS errors happening mid-flight.
Or in your case, if telemetry tells you, mid-flight, the same thing, you should be safer.
George
Thanks, George! That is indeed good advice!
Hi Benny,
Just joined the forum so this comes way late. I know the discussion is about RTL but I was currious, did it by any chance take off in the direction of your home? I was test flying an APM 2.5 when I had a similar experience. In my case a jackass intentionally (I saw him) ran over my quad before I could get to it. However, after much thought about that incident, my quad may have been attempting to go HOME and some other failsafe was operating.
Bobster256
Hi Bobster256,
I think it went in an opposite direction from my home, but the truth is it all happened so fast, I canât really tell for sureâŚ
I think it was really the mismatch between the radio failsafe and the one of the Pixhawk.
Anyway, only God can tellâŚ
Thanks!
Benny
@Andre-K correct me please if Iâm wrong. The Taranis or - better - the X8R receiver must be setup in order to follow a behaviour in case the radio link should be broken (radio off, radio battery down etc.).
How can we setup both the Pixhawk and the X8R so the FCU will control the RTL?
There are two kinds of RTL: voluntary RTL flight mode set by the pilot, and RTL due to radio TX/RX issues.
As mentioned, EMI goes up quite a bit while the copter is flying. A low PDOP and high # of sats can change in an instant when the motors ramp up. A good way to check for this, is to take off and land under stabilize or a mode like alt-hold (and avoid using a gps mode) where you can look at the logs after and see if the GPS maintained under all circumstances. Check the UBX messages in the dataflash .bin. The important ones are jamInd, noiseperms and acgCnt. This thread has some good info on those values and EKF variables to monitor related to GPS