That crash was caused by a collision the plane had with a much smaller plane that had violated its airspace.
If you want to hear the cockpit voice recorder of the crash in MP3, go here:
http://www.worldwidemart.com/sapienz...ssna%20172.mp3
(one of my silly little habits is to collect and MP3 CVR recordings ...)
More links of interest:
http://aviation-safety.net/cvr/cvr_ps182.htm
http://www.airdisaster.com/special/special-psa182.shtml
... yeah, I know, I find air disasters a little TOO interesting...
sapienza