Today I was flying the Cessna citation X. Set my altitude to 45,000ft and speed to just over 300. As I approached the Fl10 mark I engaged my AP heading. Everything was running smoothly, beautiful view, beautiful aircraft, beautiful pilot :). However everything went pretty ugly when ascending past FL400, suddenly the aircraft started swinging violently left and right. There was no wind and turbulence certainly wouldn’t cause this. As I disengaged HDG and re engaged it the problem continued, starting from small fluctuations to major swings. Ended up me having to descend to 30,000ft and manually fly the aircraft. NOT FUN.
I have experienced this a couple times, anyone else? Thanks.