For general aviation pilots, the six biggest worries aloft are:
• Flying into bad weather that has the capacity to kill you (icing and turbulence being the biggest factors for instrument-rated pilots)
• Flying into instrument conditions without being instrument rated (the JFK Jr. crash serves as an example)
• Having a mid-air collision (there goes the wing)
• Losing an engine on takeoff less than 1,000 feet AGL (#@$%$&*#)
• Encountering a structural failure (main wing spar collapses)
• Encountering a complete instrument failure while flying in instrument conditions (Are my life insurance premiums up to date?)
Thankfully, the pilot has some control over the first ...