I have flown this afternoon in a field near Madrid (Spain). Temperature was 103 F (39 C). I connected the iPad mini4 with no cover, and was flying from a shadowy spot. The video transmission was horrible, even selecting 1980 video, airplane mode (I have flown more than 200 batteries before with 4G mobile network and the same iPad mini4) and manually selecting one video channel instead of auto mode. No way to be able to see anything live from the camera but green or black screens!
A friend let me try his iPad
mini 2, but no way to ameliorate...
After this, and while in flight, he disconnected the iPad from the RC and connected his small (4 inch screen) Android phone with Litchi application on: Like in a miracle, we could see there was a perfect video feed on real time! I tested it during a couple of minutes and decided to land the P4 with a 32% battery. Battery temperature was 68 Celsius (155 Farenheit), but motors were not that hot.
Waiting until sunset at 21:45 local time, with ambient temperature down to 32C (90 Farenheit) I tried again my very sane iPad mini 4 with a new battery and everything went well: no problems at all with the video transmission, as in 'old times'. I was able then to demo the new modes (Draw, Tripod, Terrain following, etc) and see everything as expected on the iPad screen.
It seems, then, that in my case it is a temperature problem. I said earlies in this post that could be a firmware update problem, but probably the bottom cause is the internally generated heat. Maybe not only in the iPad, but in remote controller as well. I do not remember experiencing as many video problems last summer at similar temperatures, but again, the new updates and their need for more calculations might worsen the problem today. Hipe rhis can be of some use to some of you.