I have owned an original IRIS since March of 2014. I just recently got around to installing the IRIS+ upgrade kit. The upgrade kit came with a GPS shield which I installed as part of the upgrade. You should know that I had also updated Mission Planner, the firmware to the latest releases as well as moving the Pixhawk as advised by the Improvement Update. I then recalibrated the radio, Acceleration, ESC, etc. That is when the weirdness started. I couldn't arm and received error messages for NEED GPS FIX, BAD VELOCITY, HIGH GPS HDOP. After reading a number of forums I found that I could not arm without setting the GPS_HDOP_GOOD parameter to 500! After communicating with Alan at 3DR I was cautioned that this value should not exceed 230 (Alan and 3DR support has been great). So I suspected a GPS hardware failure. I opened the shell and removed the GPS shield and traced all the connections. Everything looked good so I reassembled the IRIS+ without the shield. The result was GPS lock in 30 seconds! I dialed back the GPS_HDOP_GOOD parameter to 150, and I am arming and flying around with no problem. So I am wondering if anyone else has had similar experience with the GPS shield. I had a similar issue with my Blade 350QX...in an effort to block the EMI from my GoPro H3+ I applied copper tape to the bottom and sides of the Taoglass antenna (I upgraded this from the original antenna). I was never able to acquire GPS Lock until I removed the copper tape from the sides of the antenna. Should I reinstall the IRIS+ GPS shield or simply ignore it?