Midair collisions in US civil aviation, 2000-2004: the roles of radio communications and altitude

Background: Midair collisions are destructive to aircraft and often fatal to occupants, with the additional possibility of death and destruction on the ground. We sought to determine the characteristics of civil aviation mid-air collisions in U.S. airspace with focus on the altitudes at which the collisions took place and radio communications prior to the collisions. Methods: Accident reports published by the National Transportation and Safety Board for the period 2000-2004 were analyzed using descriptive statistics. Additional information was extracted from the narrative report of each accident. Results. During the 5-yr period, 48 collisions in U.S. civil aviation occurred with 78 fatalities and 7 persons severely injured. There were 46 aircraft destroyed and 37 substantially damaged. In 14 cases no radio communication was reported. In 19 cases there appeared regular radio communication with a tower or other aircraft. Conclusions: Midair collisions resulted in fewer severe injuries at lower altitudes. Visibility and weather were not contributing factors. Radio communication is recommended to assist aircraft where practical, but pilots need to be made aware of the limitations of radio communication for the avoidance of midair collisions.