Thanks to Finagle's Law (or just ignorant writers), on TV a system's failsafe will never work when it's needed the most, nor will it actually be failsafe -- usually it'll be quite the opposite, sometimes referred to as 'fail deadly'. The only reference to an emergency shutdown you'll be likely to hear is a panicked tech yelling "It won't shut down!" as the system runs wild. It's supposed to make the phenomenon of Explosive Instrumentation more plausible, by acknowledging it's not supposed to blow up in your face, but a failure elsewhere of a key safety lockout means it can, and will. It also justifies how something that is supposedly governed by industry-wide standards, regulatory law, and years of engineering refinements could go so horribly wrong in the first place.