After losing my 1st 2 sparks to flyaways in the mountains where I live. I bought refurbished unit and decided to fly somewhere else for a while. In the mountains I've flown over 1 mile with no connection loss unless hills or trees got in the way. I've now flown the new bird in 3 different locations and in each case had connection loss within a few hundred feet with clear line of sight. At first I thought I might have a defective unit until I noticed that it was using the 5.8 GHz band. My understanding that 2.4 Ghz has longer range, but is more susceptible to interference. Is the Spark using 5.8 GHz because the populated areas are more prone to interference than my mountain home or is something else going on?