I drove straight from Los Angeles (sea level) and free soloed the regular route on Mt Whitney (almost 15,000 ft above sea level). I used to do this regularly, but something in my physiology had changed and I got a surprise altitude sickness toward the top of the cliff. Suddenly, I blacked out on a ledge. I ended up making very bad decision and instead of down climbing and getting to lower altitude as soon as possible, I climbed to the top thinking it would be easier to walk down the hikers trail. I ended up spending 10 hours at high altitude. It took every bit of strength and experience to get back to the parking lot. I got in the drivers seat of my car (too weak to take my climber’s pack off) and drove straight to the emergency room. Blood work showed anaerobic damage as if I had run multiple marathons. I didn’t feel normal again for many weeks. Lessoned learned.
I blacked out on the horizontal ledge half way up the cliff face (center).