By the 1990s, there were 423.7 million domestic passengers and 41.8 million international passengers each year. With this many aircraft, accidents are bound to happen. Airports have become extremely busy and several of the larger ones have an aircraft landing or taking off every 60 seconds, around the clock. Many smaller airports also have heavy loads. Weather and nightfall play significant roles in accident prevention and unexpected fog or storms may require rerouting, creating more congestion in other areas.
Aircraft crashes are especially difficult for disaster management for a variety of reasons.
An aircraft may be reported overdue but the precise location is unknown. Rugged and remote terrain may hide aircraft for months, even years. Weather may hinder or even prevent aerial searches. Injuries are often extremely severe and delay in medical assistance is likely. The aircraft fuel is highly flammable and often ignites as a result of a crash, further complicating rescue and life saving efforts.