Fail-Safe/Fail Secure: All systems fail, whether due to accident, error, or attack. What we want is for them to fail as safely and securely as possible. Sometimes this is as simple as a dead man’s switch on a train: if the driver becomes incapacitated, the train stops accelerating and eventually coasts to a stop. Sometimes this is complex: nuclear missile launch facilities have all sorts of fail-safe mechanisms to ensure that warheads are never accidentally launched.
