Interference or someone "stepping" on your frequency causes the servos to go nuts.

You may not notice this immediately as it takes a few seconds for you to realize that you no longer have control.

You find out about it when your plane does something very strange or noses in, turns over, etc.

Your description of the problem is typical of being "shot down".


Were you flying at a Club Field at the time?

Did you have your frequency pinned?

Did you scan the frequencies?