Hi friend..so I have a question: Most (…if not all) of my flight sim flying history has involved flights less than 12,ooo’ mSL. However, yesterday I attempted to ‘fly the MU-2 on a long cross country from Michigan to Alabama. I was attempting to go to fL 20,000, however, shortly after passing 15,000 the whole XP12 computer screen started to slowly black out. When this happened I realized for the first time that XP or the MU-2 app was illustrating a hypoxia “black out” condition because of either a) lack of supplemental oxygen or b) failure to adjust the cockpit pressurization. Q: Have you experienced this and if so, how did you correct it? Thanks in advance.. Randy