This work examines the causes of airplane accidents and what private and public policies are needed to improve aviation safety. It begins by examining the safety record of the United States commuter airline industry in the post-deregulation era characterized by increased emphasis by airlines on cost control and growing pressures on the air traffic control and airport system. The authors go beyond the safety of the scheduled airlines to examine the reasons for accidents in the nonscheduled and general aviation segments of the United States industry, where the bulk of fatalities occur and where airline pilots increasingly receive most of their training and experience. They then turn to an examination of aviation safety throughout the world, first with a detailed comparison of Canadian and American aviation safety, and then with a look at air safety in all regions of the world and the safety performances of all the world’s major airlines. Three emerging issues are then examined in greater detail: assessing the margin of safety, worldwide aging of all airline fleets, and terrorism.