The value of rigorous error checking is exemplified in any of the several catastrophes arising from poor software engineering. Examples abound, but a few are particularly illustrative of what happens when bad data and design go unchallenged.
On 4 June 1996, the first test flight of the Ariane 5 rocket self-destructed 37 seconds after its launch. The navigation code from Ariane 4 was reused in Ariane 5. The faster processing speed on the newer rocket caused an operand error. The conversion of a 64-bit floating-point value resulted in a larger-than-expected and unsupported 16-bit signed integer. The result was an overflow that scrambled the flight's computer, causing too much thrust to be passed by the rocket itself, resulting in the crash of US$370 million worth of technology. Widely considered to be one of the most expensive computer bugs in history, the crash arose due to mistakes in design and in subsequent error checking.
On 15 January 1990, the...