Before take off that's normal the bird is just getting synced up.
During flight it is most likely heavy 2..5 ghz area.
You can get apps that tell you how much spectrum is in use in your area.
You will find normal flying areas that are great one day mite not be so great the next time.
Yesterday I had to abandon an area I fly, I swear it was a lady running the track with large head phones on. But I don't know for sure, I do know I moved to a new location and everything was spot on.
Check the HD Connection up above when this happens it will tell you quite a bit as well as a wifi app.
Clear you cache often! since I started doing that religiously I have far few problems.
Android Nexus 7 II P3P
Cheers