The 5-M Factors are a model called Man-Machine-Medium-Mission-Management, and are used to examine the nature of accidents in the transport industries. It was started by T.P. Wright's Man-Machine-Environment triad at Cornell University. The 5-M incorporates a diagram of 3 intertwined circles and one all-encompassing circle. In each of the smaller circles "Man," "machine," and "medium" are placed. The large circle is labeled "Management." The space in the middle where they all meet is called "Mission," which is the objective the other four M's have in common.
It can also be used in troubleshooting - 5 factors Man-Machine-Materials-Method-Medium (or environment)
References
5 M factors Wikipedia(Text) CC BY-SA