Most of the time when a pilot saves the day he just disconnects the autopilot and writes an incident report. There's been at least four inflight upsets due to autopilot or sensor malfunction in the past few years that I can recall. Some of these caused serious passenger injury. Latest one I heard about here: http://www.aibn.no/Luftfart/Rapporter/13-18
Another one: http://en.m.wikipedia.org/wiki/Qantas_Flight_72