Not sure why this issue was locked, but perhaps StefanG locked it when he reminded us to keep things civil…but the issue still exists. I will want to see how this gets resolved as I will be rebuilding my crashed Iris (it landed upside down and the GPS and Pixhawk were both damaged (GPS destroyed-Pixhawk MIGHT be OK???) likely because of the close contact…so I, for one, will be interested in hearing how others find solutions to this.
[color=#00BF00]Yes, indeed I did. But we also try to keep it so that each problem gets it’s own thread, so it’s easier for searching users to find 
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About the question - I have a test setup for my groundstation development where I mounted my test-Pixhawk and the 3DR GPS/compass module right side-by-side on a wooden board - distance about 1cm. I usually get 8+ satellites and HDOP around 1.7-1.8 indoors(!).
So I don’t believe, it’s RFI from the Pixhawk which messes with your GPS. What else do you have in your Iris?
A year ago, I found by accident (literally…) that the Hobby King 720p wing camera is a great GPS jammer with an effective jamming range of well 10cm.
Any kind of telemetry R/C, like FrSky, would also be a candidate to look at.
Besides - if the GPS fails when in any GPS-assisted mode, the system should go into failsafe and autoland. When the external compass fails, it should use the internal sensors. I don’t see how a failure of the GPS/compass would cause a crash in which the Iris would land on it’s back.
Do you happen to have any logfile from the crash flight?