Based on T.P. Wright's original work on the man-machine-environment triad at Cornell University, the 5M model incorporates a diagram of 3 interlocking circles and one all-encompassing circle. The smaller circles are labeled Man, Machine, and Medium; the intersecting space in the middle, where they all meet, is labeled Mission; while the larger circle is labeled Management:
- Man (people): including the physiology and psychology of those involved, as well as their performance and proficiency.
- Machine (equipment): including the design, manufacture, maintenance, reliability, performance, etc.
- Medium / measurement (environment, inspection): including weather, terrain, obstructions, lighting, etc.
- Mission (purpose): the reason these three factors are brought together.
- Management (leadership): the prevailing supervisory approach in terms of regulations, policies, procedures, and attitude involved in establishing, operating, maintaining, and decommissioning.
These have been expanded by some to include an additional three, and are referred to as the 8 Ms:
- Method / mother nature (process, environment)
- Material (includes raw material, consumables, and information)
- K., Cusick, Stephen; T., Wells, Alexander (2012). Commercial aviation safety. McGraw-Hill Professional. ISBN 0071763058. OCLC 707964144.
- Ballesteros, J.S.A. (2016). Improving Air Safety Through Organizational Learning: Consequences of a Technology-led Model. Routledge. ISBN 1317118243.
- Stolzer, A.J.; Goglia, J.J. Safety management systems in aviation. ISBN 1317059832. OCLC 944186147.
- Bradley, Edgar. Reliability engineering : a life cycle approach. ISBN 1498765378. OCLC 963184495.
- Weeden, Marcia M. (1952). Failure mode and effects analysis (FMEAs) for small business owners and non-engineers : determining and preventing what can go wrong. ISBN 0873899180. OCLC 921141300.
- Nathan., Crutchfield, (2008). Job hazard analysis : a guide for voluntary compliance and beyond : from hazard to risk : transforming the JHA from a tool to a process. Elsevier/Butterworth-Heinemann. ISBN 0080554164. OCLC 182759248.