The majority of general aviation crashes are the result of weather affecting the flight. Useful steps now underway include better provisions of real-time weather information to pilots, better weather information and forecasts for trip planning, and cameras at airports to verify weather information. Other factors in crashes are pilot error and equipment failure. These are best addressed through pilot training.
Source: National Transportation Safety Board; Annual Review of Aircraft Accident Data
Source Data available at: http://www.ntsb.gov/publictn/2003/ARG0302.pdf