Hello I`d like to share my first experience with “flyaway”. Before that fly I did all necessary things from my check list: 1. Ajusting the temperature of the quadrocopter to the outdoor one (7-10 min.) 2. Fixing to more than 6 sats. 3. Compass calibration. 4. Starting the timer (alarm on 14 min.) after turning on the engines. 5. Checking the proper HP (home point) by flying in a circular in HL mode. After 10 min and 23 sec. of stable flight my Phantom suddenly lost control. I managed to turn off the controller. The Phantom stabilized its flight and was heading to HP. Not so long after a few sec. it speed up to 55 kmph just in the opposite direction to the HP. I switched the controller off again and in a few sec. the Phantom started its way back to its HP. I was afraid that the reason of “flyaway” was caused by loosing sattelites so I decidet to switch to manual mode. That was a mistake because the copter fell down from 15 meters to the ground. I found it in one min. thanks to remembering the direction of last seen position and my tracker installed on Phantom. I was very surprised when I found that the copter, the gimbal, GoPro B3+ and tracker were intact. Only the battery slipped from the copter. After that experience I downloaded data from my FLYTREX Core 2 unit just to analize the flight parameters. I was surprised when I got to know that the number of sats was 10-11. It was obvious that GPS fix was OK all the time of the flight. I focused on the terrain to find out what caused the flyaway. Examining the track of the Phantom in Google Earth I was surprised that the direction of “flyaway” was in one direction. I know that there weren’t any dangerous antennas or metal structures. The nearest BTS (base transceiver station) was 2.16 km SE. I realized that the direction of “flyaway” was exactly the same as the direction to the BTS. It`s well known that flying close to BTSs can interrupt connection with any radio controlled units but what distans is safe? I found out that there are mostly two types of antennas that are used in BTSs: sector and directional ones. The directional antennas work by focusing energy in any sort of direction other than just letting it radiate at random in all directions. I let to plot straight line from “my “ BTS to nearest one and the line matched exactly the “flyaway” track. I realized that my quadrocopter crossed the radio beam from one of directional antennas mounted on BTS. That experience tought me that I should add another number to my check list: 6. Plot straight line from the nearest BTS to all in distance about 20 km then avoid crossing the lines. Please check Your "flyaway" sities to proove it.