I have a 15s and a month ago it had been flying fine and all at once the wings rocked and started to porpoise and any input to recover failed.Found the plane 2 blocks away in a bush.(no damage)I discovered that the battery had a shorted cell and was puffed up.Apparently when the voltage was unbalanced the receiver went crazy due to a low voltage condition.You may want to check your batteries.Since replacing my battery there have been no issue.Hope this helps