Here's what can happen if you haven't set your altimeter correctly:

http://uk.youtube.com/watch?v=alo_XWCqNUQ

January, 2004, of the USAF Thunderbirds F-16 ejection at Mountain
Home AFB, Idaho. This compilation produced for AVweb by Glenn Pew
( http://www.glennpew.com/video.html ) includes all previously
released footage and images made available to AVweb at the time,
plus the results of the official investigation. For more, see:
http://www.avweb.com/avwebflash/briefs/186633-1.html