Many times while hiking (and/or Geocaching) we see our GPS (in our phone and Delorme PN-60) going awry, reporting that you are somewhere where you are not. This happens next to cliff faces, in gulleys and canyons, any time there is multipath reception where the signals bounce off walls. I am wondering if anyone has done any testing with the phantoms. I would think it is best not to fly in GPS mode in such locations. However, flying x feet above the cliff face (when you launch from the top of the cliff) should be okay, but I am looking for someone who has done some good testing in this area. I plan on flying today next to a cliff face so your early reply would be much appreciated. Thanks so much.