Those on no flight plan who had an accident that included the above weather conditions between 1998 and 2007 led the fatal category with 203 fatalities. But those on IFR flight plans came in second with 106. Those on VFR flight plans were much lower, with only 49 fatalities over the nine-year period.
Part 91 operations in fog, obscuration, and below minimums conditions led the statistics with 340 fatalities. In second place were charter operators with only 38 fatalities.
What’s the conclusion? Kenny has these observations: “The relatively low number of fog accidents [for aircraft] on VFR flight plans–and the high number on flights that didn’t file any–probably says something about the risk attitudes and flight practices of the pilots involved. IFR pilots are expecting low visibility, so reports of fog won’t necessarily deter them from trying the approach, but it [fog] will make things get bad in a hurry if [the pilot] gets off course or goes below minimums.”