One is a crash involving a large passenger aircraft. The other is an airplane crash causing casualties on the ground. Despite the large number of planes flying over heavily populated areas, the number of crashes killing or injuring non-passengers is quite small. In general, crashes are most likely to occur within five miles of an airport, typically along flight paths. The area within a five mile radius of airports in the Puget Sound region are heavily populated and therefore could result in a mass casualty event if a plane crashed in these areas, even if the plane itself was not a passenger aircraft.
Weather is a significant factor in air transportation accidents.
Down bursts, thunderstorms and ice are the primary weather related events that increase risk. There has not been a major air accident in the Puget Sound region in recent history. However, accidents in other parts of the country allow us to examine the potential vulnerabilities we face in this area. In 1995 there were 175 deaths associated with large scheduled airline traffic and 732 deaths associated with general aviation flights. The Puget Sound experiences extensive air traffic of both these types.