Breaking the mishap chain

Human Factors Lessons Learned From Aerospace Accidents and Incidents in Research, Flight Test, and Development
By Peter W. Merlin, Gregg A. Bendrick, and Dwight A. Holland

This book is a series of case studies looking at mishaps with aircraft and space vehicles. It examines what leads up to the problem that occurred and how such accidents can be avoided in future.

Test flights are always thought of as being dangerous but this does not have case, what these reports examine is that the cause of failure is nearly always the accumulation of several errors in the system, design or testing process. Sadly in these cases the end result is often loss of life or serious injury. As the title might suggest the studies focus on the human aspects rather than technical defects, a lot of the focus is on the test pilot but it soon becomes apparent from reading these just how many other people are involved in a flight.

The studies are divided into three sections, Design Factors, Physicological Factors and Organizationl Factors each section looks at 3 different craft and situations. The design factors looks at the aircraft user interface, re-use of user inputs and pilot induced oscillation. The physcialogical factors focus again on the pilot and their ability to physically and mentally handle the stresses of flight. One of the cases inspired the film and series “The Six Million Dollar Man” and shows that even experienced test pilots can become distracted if given too much to do. Finally the organization factors looks at how the procedures and origanisation can let down the pilot. There is an analogy of layers of swiss cheese with holes all lining up to show a hole all the way through, a problem that could have been caught and corrected at many points is let slip through the net. One particular disaster was the side effect of trying to combine a test flight with a photo oppertunity, something that is strongly advised against.

The photos and diagrams in the studies are not the most detailed but do add and explain the text. There is quite a lot of aerospace terminology in the studies but it is explained along the way. I did not need to use any additional research to understand acronyms and terms but I did find it necessary to cross reference earlier parts of chapters. Those with a basic technical background should have no issues with understanding the studies.

Even if you are not in the business of making safety critical systems I feel that understanding how these errors accumulate and interact can help with designing and testing of any system.

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