I was doing a free flight from a cold start just to mess around and get a feel for the aircraft. I had on my oxygen in the front seat but didn't turn it on in the back. After flying around at 29000 feet for a little bit I noticed my controls wouldn't work and I could not click on anything. Hopped into the back and black screen. My guy in the back passed out. Back into the front seat I can see perfectly but it acts as if I'm blacked out as well. Has anyone else had this problem? It's got me afraid to fly up high in multiplayer.