Let's collect data on the conditions / places where we lost signal (interference), or compass went wrong, or gps failed... I'll start it off with a story. This evening I was flying near the top of a building in the city that has GSM antennas (2) mounted up there. While near them, flying in CL mode; at one point I've found out that flying BACK actually moved the bird FORWARD. I tried twice, before getting panicked (as every forward leap moved it towards the building and towers). I switched to Failsafe and it came above me. From there I took control and landed. Still shaking. Were the cell towers the issue?