Originally Posted by
Whirlybird
...They can probably find out which direction the helicopter was facing when it crashed...or maybe not...
If there was a GPS on-board then the track of the aircraft for the whole of the flight should be recoverable from unit memory, at good resolution, by the manufacturer.
Flying in mountains in reduced visibility can make it difficult to judge whether you are going to clear the ridge line, or not. Given the crash was close to the top of the mountain, it's quite possible he may have thought he was OK, until it was too late. But if you stick to the weather rules for visual flight then you have adequate visual cues for judging height when crossing a ridge line.
There is an optical illusion where you think there is clearance between the cloud base and the ridge line, but in reality the clouds go down to the tree tops on rising terrain. You must be able to clearly see the valley on the other side of the ridge before attempting to cross. Crossing the ridge at an oblique angle is a safer option than flying directly at it, gives you more of an opportunity to turn away at the last moment if you miss judge it.