That was a well known accident at an airshow. More specifically, it was Air France Flight 296 flying over the Mulhouse-Habsheim Airport in France. It was supposed to make a gear-down flyby of the audience at 100 feet but the pilot miscalculated and came in too low. The cause of the accident is listed as pilot error, although that's dispuited. The autopilot wasn't even in use. If it was it probably would have prevented the accident since it would never have let the plan fly so low & slow to begin with. See http://en.wikipedia.org/wiki/Air_France_Flight_296 for details.