According to the “Ariane 5 Flight 501 Failure: Report by the Inquiry Board”, the failure that caused the Ariane 5 was a design error, namely of an Operand Error. The report says, “The exception was detected, but inappropriately handled because the view had been taken that software should be considered correct until it is shown to be at fault” (Lions, 1996). This view manifested itself in the use of extant software from Ariane 4 that was used for Ariane 5 because, to simplify, it worked well for Ariane 4 despite this previous flight having a different flight pattern and other design elements. The failure was in the inertial reference system which wasn’t a problem with Ariane 4, but was a problem, and the main failure occurring within the first
