1. Human Error: Anatomies of Accidents Anthony J Spurgin IEEE Section Meeting 8-26--2009

2. Human Error: Anatomies of Accidents Outline of Presentation Introduction Accidents cover all industries –Listing of a number of accidents given Brief general discussions on some of the accidents –Role of NTSB and Human Reliability Experts –View of Media Causes of Accidents, including human error – In Depth Analysis of a few accidents Lessons Learned, effect of context Comments

3. Introduction: Some Assumptions About Accidents Everyone knows what an accident is: something that happens to others! Usual assumptions: Random failures, and usually involving people Humans cannot be relied upon and cause accidents Humans have to rescue us from machine failures Most accidents are due to single failures We cannot do anything about accidents

4. Analysis of Accidents Very visible accident reports from: –Nuclear, Chemical plant, Airplanes, Railways, roads Brief discussion about the accidents Some accidents will be discussed some detail. NTSB Accident reports focus on specific causes - comment Human Reliability persons consider what are the causes of accidents and how to mitigate or minimize their effects

5. IndustryAccident Consequence Nuclear 3Mile Island 3/79 $2 Billion, no deaths short term Nuclear Chernobyl 4/86 Deaths:36 short 4000 long term +++ Space Challenger 1/86 Shuttle loss and crew(7) Space Columbia 2/04 Orbiter and crew on re- entry Air TransportTenerife 3/77 2 x747s crews and most passengers (583) Air TransportJFK 11/02 Airbus 300, 265 plus 5 on ground Petro-Chemical Bhopal 12/84 3,000 plus 8,000 deaths Petro-Chemical Texas City 3/05 $1.5Billion, 31 deaths, 100injur’d Oil-RigPiper Alpha 7/88 $3.5 Billion, 165 deaths Rail Way Flaujac 8/85 31 deaths & 91 inj Rail Way King’s Cross 11/87 31 deaths

6. Human Error Are Humans prone to errors? What leads to humans taking erroneous actions? Careful analysis of accidents indicates that one has to consider the context under which the accident took place The context can vary according to the accident

7. Accident Analysis Process Gain access to all available reports, Google, Wikipedia Produce an independent evaluation of the events Produce an event sequence diagram of the events Draw conclusions relative to the various impacts on human error: design decisions, training, management involvement, etc.

8. NASA Challenger Accident

9. Three Mile Accident

10. JFK Airbus Accident

11. Boeing 747s Tenerife Accident

12. Texas City BP Refinery Accident

13. Texas City BP Plant Accident

14. Flaujac (South West France) Railway Accident

15. Human Error: Context Effects and other Observations Training Information Layout and Availability Procedure Layout and Organization Prior Design influences and effects Management Influences

16. Comments Official Accident Reviews often result in Human Error being the cause, often the human is set-up to fail and does PRAs rely on the combination of equipment and human error estimation to estimate the risk of operation The PRA is a good start to the process but one can see that more needs to be done to cover things like the effects of design limits and HRA methods to be based upon context rather than the task The predicted human error rate range is bounded and this has consequences for any designer and manager