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--- articles:human_factors [2022/02/26 12:42] – [What about "Zero Defects"?] rrandall
+++ articles:human_factors [2023/03/09 08:46] (current) – [Are nonconformities resulting from Human Factors "Common Cause" or "Special (Assignable) Cause" Variations?] rrandall
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-Since human factors are mentioned in 10.2, many assume that they are required to eliminate root causes associated with human factors. In the vast majority of cases, this is not true. I recommend reading the AMT  (FAA "Aviation Maintenance Technician”) Handbook because it clearly emphasizes/focuses on Risk Mitigation (rather than corrective action) when managing human factors.
+Since human factors are mentioned in AS 9100, sec. 10.2, many assume that it is required to eliminate root causes associated with human factors. In the vast majority of cases, this is not true. I recommend reading the AMT  (FAA "Aviation Maintenance Technician”) Handbook because it clearly emphasizes/focuses on Risk Mitigation (rather than corrective action) when managing human factors.
 The AMT Handbook: Chapter 14, Human Factors, can be downloaded from:
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 {{ :articles:scope_and_type_of_human_error.png?direct |}}
-<note tip>An excellent source of news and information about Aviation-related Human Factors is the "[[https://www.system-safety.com/Aviation%20HF%20News/AVIATION%20HUMAN%20FACTORS%20INDUSTRY%20NEWS.htm|Aviation Human Factors Industry News]]". Multiple editions of this online magazine are freely available in PDF (2006-2020). Learn from the mistakes of others.</note>
+<WRAP center round tip 80%>
+An excellent source of news and information about Aviation-related Human Factors is the "[[https://www.system-safety.com/Aviation%20HF%20News/AVIATION%20HUMAN%20FACTORS%20INDUSTRY%20NEWS.htm|Aviation Human Factors Industry News]]". Multiple editions of this online magazine are freely available in PDF (2006-2020). Learn from the mistakes of others.
+</WRAP>
 ===== Are nonconformities resulting from Human Factors "Common Cause" or "Special (Assignable) Cause" Variations? =====
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 ^ Action  ^  "Risk Mitigation" or "Risk Elimination"  ^
-| Fuse box lock-out procedures so that power cannot be turned on before an electrical repair is complete and all personnel are out of harm's way.  |  Risk Mitigation (because workers can fail to follow a procedure)  |
+| Fuse box lock-out procedures so that power cannot be turned on before an electrical repair is complete and all personnel are out of harm's way.  |  Risk Mitigation (making it difficult for workers to unknowingly re-introduce electrical power)  |
 | Guide pins to guarantee proper alignment.  |  Error Proofing  |
-| Color-coding of components that otherwise look similar.  |  Risk Mitigation (because workers can still make mistakes.  |
+| Color-coding of components that otherwise look similar.  |  Risk Mitigation (because workers can more quickly & easily differentiate by color rather than reading text).  |
-| Bins of parts that are electronically connected to the bill of materials through a bar code scanner, so that only the proper bin door opens for a given product.  |  Error Proofing  |
+| Bins of parts that are electronically connected to the bill of materials through a barcode scanner, so that only the proper bin door opens for a given product.  |  Error Proofing  |
 One of the most common failed attempts at error proofing we see appears in documents, e-mails & text messages. Of course, I'm speaking of the auto-spell correction. These have resulted in some hilarious memes. These are much better described as "risk mitigation" controls.
-===== What about "Zero Defects"? =====
-It is surprising that a common topic of debate between quality professionals is whether the "Zero Defects" concept is valid.
-“Zero Defects” is a //motivational// management approach that first appeared in the “//Quality and Reliability Assurance Handbook – A Guide to Zero Defects//” (4155.12H) published by the U.S. Department of Defense on November 1, 1965, which explained: “//Zero Defects is a __motivational__ approach to the elimination of defects attributable to __human error__//”. And: “//Zero Defects is dedicated to preventing defects by detecting and removing the causes of their generation. This is an attempt to reverse the unquestioning acceptance of __human error__ as a normal byproduct of personal effort//”.
-However, the “Zero Defects” concept didn’t gain widespread popularity until it was promoted by Philip B. Crosby in his book “//Quality is Free//” (1979). Crosby is credited with having developed the “Zero Defects” concept during the early ‘60s while working at the Martin Company as the quality control manager overseeing the Pershing missile program.
-This is diametrically opposed to the philosophy and teachings of W. Edwards Deming, who repeatedly showed that, no matter how vigilant the employees, every process contains inherent (i.e., natural “Common Cause”) variations resulting in defects. This was most popularly demonstrated through Deming’s “[[https://www.youtube.com/watch?v=ckBfbvOXDvU|Red Bead Experiment]]”. In fact, point 10 of [[https://deming.org/explore/fourteen-points/|Deming's 14 points]] specifically rejects the “Zero Defects” concept, stating: "//Eliminate slogans, exhortations, and targets for the work force asking for __zero defects__ and new levels of productivity. Such exhortations only create adversarial relationships, as the bulk of the causes of low quality and low productivity belong to the system and thus lie beyond the power of the work force//".
-When performing causal analysis, we must be able to identify and link an “assignable cause” to a problem in order to have a “root cause”. “Assignable Causes” can often be eliminated (e.g., through corrective action). However, when unable to identify and clearly link an “assignable cause” to a problem, we must recognize and acknowledge that those variations are most likely inherent to the process and cannot be eliminated; without completely re-engineering that process. And re-engineering a process may be cost-prohibitive… or impossible (e.g., due to technical constraints/limitations). However, there are usually risk controls we can institute to mitigate the likelihood/probability and/or consequences/impacts of these problems to an acceptable risk tolerance level.
-Ultimately, the "Zero Defects" management approach should have been abandoned long ago. Unfortunately, this delusional concept has persisted well into the 21<sup>st</sup> century!