@AC
"I can't imagine how he could just disapear in the United States"
Bad luck. Or maybe more likely, not taking sufficient care with lower-level risks.
One of the UK's top female rock-climbers died about 10-15 years back after slipping on a walk down that any kid in trainers would happily scramble up and down all day. And just last month, the British Hang-gliding and Paragliding Association's magazine carried an obit for a pilot with 20+ years' experience who died falling off the roof of his house whilst doing DIY.
Remember that the USA is a big place with areas that have seriously nasty terrain and not many people there - they called those areas of Nevada the Badlands for a reason. You might think that it'd be easier to find a crashed pilot in the USA than in, say, the Sahara Desert, but there's plenty of places where your chances aren't substantially different, especially if you're not in good shape after the crash.