Hardware kills people too, sometimes in subtle ways. http://en.wikipedia.org/wiki/United_Airlines_Flight_232 http://en.wikipedia.org/wiki/United_Airlines_Flight

Hardware kills people too, sometimes in subtle ways. http://en.wikipedia.org/wiki/United_Airlines_Flight_232 http://en.wikipedia.org/wiki/United_Airlines_Flight_232 The combined utility of hardware and software interlocks is that they're complementary: Sometimes it's easy to specify an interlock in the language of hardware: Never, under any circumstances, should it be possible to slew an avalanche-control howitzer to point at permanent structures; let's use a steel pipe to block the barrel from traversing beyond safe limits. Sometimes it's easy to specify an interlock in software: Never, under any circumstances, should a rocket launch unless every desk at mission control has authenticated their assent with the main control system. When interacting with the real world, real-world interlocks are handy, but they're hardly sufficient to guarantee safety. Nothing is.