After declining for decades, the U.S. airline fatal accident rate began to “plateau” in the early 1990s. Because airline flying volume was projected to double in 15-20 years, the industry was concerned that the number of accidents from doubling the volume without reducing the rate could generate undue public concern.
Commercial aviation is a complex system that consists of several subsystems – airlines, manufacturers, airports, pilots, flight attendants, air traffic controllers, maintenance personnel, and regulators – that must all work together in order for the entire system to function. Because the subsystems are coupled, changes to one subsystem can have effects on the other subsystems. One of the major challenges of improving the safety of a complex system is the possibility of unintended consequences.