hello every body

Actually I was trying to fly my AC with RC & OTG cable and after checking every thing it needs to fly ( airplane mode, calibration compass, ..... etc) and after reaching 19 meters only I lost connection between the RC and AC and the Mobile screen blanked and indicator lamp of RC becomes red around 4 or 5 seconds the AC automatically start the RTH and reconnected again to RC automatically and indicator lamp retuned green . I tried many times and same result. By the way I live in kuwait and I have broadband tower on my building where I tried to fly near it and only 10 Satalite showing and throw OTG cable channel mode 2.4G the heat outside was 38 C ,  Need your advice.

I see two possible factors here.  The broadband tower could be interfering with the location functionality of the craft, which may be why you only see 10 sats.  The other factor could be the wifi traffic where you were flying.  It sounds plausible that there is a LOT of wifi users with their own wifi routers, and (unintentionally) you are getting "jammed".

Do you have an opportunity to fly in a location that is less densely populated?  An open field or a park?  If you are able to fly in such a location with none of these problems, that would confirm my theories.

I agree with Charles. Changing to another location without interference will be helpful to verify the issue.