While I was out in the Alvord Desert last week, we did a shoot on July 4, and the GPS worked just fine. The next day, at the same location, I could not throttle up when I was ready because the MK GPS board had not got a 3D-Fix. This was after waiting for, oh, five minutes or so. I connected up MK Tool and looked at the MK GPS data -- I could see that it was receiving data from 16 satellites (bear in mind, out in desert, so huge sky view), but all 16 histograms were dancing up and down in the green. The numbers at the bottom of each histogram were "twinkling" on and off, and, of course, there was no fix. I went on-line (via a Verizon MiFi card) and confirmed that the Kp Index wasn't showing that we were in the middle of a solar storm. Nope. Kp = 2. I even called Gary on voice and discussed this situation with him and he did some checking on the net (thanks Gary!). I swapped out GPS receivers. Exactly the same behavior -- so it wasn't the GPS receivers. I tried a Garmin GPS hand-held that I had -- it saw about 14-15 satellites but had a tough time getting a fix too. I was just about at the point of putting the bird back in it's box and calling it quits, when, after about 40 minutes, it suddenly got a 3D-Fix and we flew the rest of the day without incident. The next day, same location, the GPS locked onto a 3D-Fix in about 10 seconds. I mentioned this to the professor leading the research group that we were shooting and he said something similar had happened when he tried to use a scientific GPS unit about 10-days prior. Where were we? https://maps.google.com/maps?q=fiel....184814&t=h&hnear=Fields,+Harney,+Oregon&z=19 Basically waaaay out in the Boonies -- way past El Beyondo. So, folks, anyone got any ideas? Secret government installation jamming the GPS? Aliens? Some atmospheric phenomenon that royally naffs up the GPS system? NSA? Andy.