Do you have any ideas what could be the problem here? This happens in flight or on the ground. Sometimes it is gone after couple of seconds and works normal, sometimes it needs reset.
**EDIT** - I changed the radio and the receiver. For the moment it is working ok. I hope it was just a bad radio (Turnigy 9x - Frsky module, worked ok for two years) Tnx Aaalie, you gave me an idea to check the radio.