> Steering was controlled by the on-board computer, which mistakenly thought the rocket needed a course change because of numbers coming from the inertial guidance system. That device uses gyroscopes and accelerometers to track motion. The numbers looked like flight data -- bizarre and impossible flight data -- but were actually a diagnostic error message. The guidance system had in fact shut down.
The real question is, why was the diagnostic error message interpreted as flight data?
The real question is, why was the diagnostic error message interpreted as flight data?
I recommend reading the original report, which has much more meat: http://sunnyday.mit.edu/nasa-class/Ariane5-report.html