In this paper, we report the results of a detailed examination of the causes of 700 fatal aviation accidents that occurred worldwide between 1990 and 2006 in commercial passenger service. We look at both scheduled and nonscheduled and both domestic and international service. We also categorize the accident aircraft as large jets, regional and medium jets, small jets, turboprops, and piston powered aircraft. We find that the mix of causes of those accidents vary substantially across regions of the world, across different kinds of service, and across different categories of aircraft.