fatal" ("Aviation Weather: The True Story," 2005). A study of four types of accidents caused by weather over an 11-year period(wind-related, low-visibility, airframe and induction icing, and thunderstorms(showed that there were "5,894 fixed-wing light aircraft accidents relating to these weather categories" (Landsberg, 1996). Of these, 48% involved "getting blown off the runway or end of the runway on takeoff or landing" (Landsberg, 1996). In the more than 1,700 fatal weather accidents recorded in the study, VFR-flight-into-instrument meteorological conditions were the leading cause (Landsberg, 1996). Possibly due to a "fascination with thunderstorms...at least 200 pilots got too close to cumulonimbus," although only 3% of weather accidents relate to thunderstorms (Landsberg, 1996). There were only a few more instances of structural icing-related accidents than those involving thunderstorms, although "airframe ice is insidious and forecasting it is not easy," as "temperature, cloud structure, air mass moisture content, and airframe shape all play a part that has confounded our ability to predict accurately where and when it will be a problem" (Landsberg, 1996).
The mechanisms involved in how weather causes aircraft accidents differ according to the particular weather condition and its effect on the pilot or the airplane. Convective motion, for example, occurs when an aircraft flies over clouds. Convection "sucks" the plane downward in the spaces between the clouds and pushes it upward when it is centered over the cloud, resulting in strong up-and-down motion ("Aviation Hazards: Thunderstorms and Deep Convection," 2006, p. 5). Convection results from warm humid air near the earth rising into the cooler air above it. Convective hazards can occur either in weather phenomena such as thunderstorms and tropical storms or in "clear air phenomena such as vertical currents caused by surface heating," which can result in turbul...