Mode errors are a ubiquitous bane: they cause us to lose our work and to kill hundreds of people. Despite the millions of dollars spent on the design of airplane cockpits, between 1988 and 1996 five fatal airline crashes were the direct result of mode errors. Many more crashes were probably indirectly caused by mode errors. What’s the lesson? If a system contains modes, people will make mode errors; if we design systems that are not humane—responsive to human needs and considerate of human frailties, we can be guaranteed that people will make mistakes with sometimes cataclysmic consequences.
