Is 'Operator Error' as Root Cause ever acceptable?



I worked as a QA tecnician in an ecoat paint facility in Southwestern Ontario, part of my job is to write corrective action reports whenever customers request for it.
In one of my reports I wrote among others "operator error" as a root cause, our customer rejected the idea and ask me to find some other reason why the problem occurred.
My question is( for those quality people out there) is an "operator error" not a valid root cause in a 7-D format corretive action report?
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Laura M

While "operator error" is a common response, most companies (B3) are starting to recognize that there is usually some other cause. Can you ask "why" was there an operator error? Possible answers could be:
1. "new employee" - so root cause may be lack of training with the C/A on the training program, or needed better visual aids for a new operator. or,
2. Operator instructions were not clear. or,
3. Bad part placed with good parts? Why? Lack of errorproofing.

I think your customer just wants to make sure operators aren't getting blamed when there may be a "better" or quality "system" related root cause. If you can ask "why was there an operator error" - and not come up with an answer, you should still look into errorproofing as corrective action. That may satisfy the customer.

Your thoughts?



Operator Error is real. Show me someone who doesn't make errors and I'll show you someone who doesn't do anything. Inattentativeness, momentary lack of judgement, distraction and just plain stupid! We do everything we can to find a reason. It will never go away. Look at some of the posts mispelling.(mine too). While it may be considered minor and doesn't really matter, it reminds me that we are all human. One mistake of the key can create an order entry error. Customers who don't accept Operator Error as a valid reason are just bullies and enjoy the power trip. Inspection was developed for just that reason, and they make mistakes, too. So there!


Fully vaccinated are you?
Staff member
True. It is real. How you address the 'problem' is what is important. For example, operator error on the space shuttle systems assembly, etc. is not acceptable. For any reason. Would you accept Operator Error by a technician performing structural tests on an older aircraft as a vaild root cause for a crash of that airplane? I don't think the flying public would accept a finding which says "Well, there will always be operator errors... We can't prevent them entirely." Not even 1 is acceptable sometimes.

The first thing I want to know if I find operator error has been determined to be the 'root' cause for a nonconformance is has this happened before? Same operation? Same machine? Same shift? Same operator? Same part?

Recurrence of operator error is a sign that there is a deeper problem.

So - you're both right. But -- look closely at the entire context before you decide whether (or how much) operator error is an acceptable 'feature' of your business processes.

[This message has been edited by Marc Smith (edited 07 May 2001).]

Dan Larsen

Refusal by a supplier to accept "operator error" as a root cause to a CA is not new. I had a supplier tell me this seven years ago (a small company in Northern Michigan, as a matter of fact). Further, I'll admit to subscibing to this belief myself.

Like Laura, I believe that if operator error is defined as the root cause, it really defines a management problem. Either the operator wasn't properly trained, was promoted without appropriate skills, or the process was not sufficiently mistake proofed.

This is not to say that errors won't occur. But the role of manangement is to design processes and systems in such a way that the liklihood of errors is either minimized or the errors that could occur have insignificant impact on the product.

I guess my question for darwinbb is this: If operator error was defined as the root cause, then what was the action taken to correct it? If the action was a reprimand to the operator ("Don't do that again!"), then the CA fails on two counts. If the action taken was training, then the root cause was a training failure. If the action taken was an example of mistake proofing (a process design change that will ensure the error can't happen again), then I'd buy the operator error argument.


hey guys,
I'm not arguing with Laura M. We have history! I'm also not talking about the space shuttle. They triple, if not quadruple inspection points on all operations to prevent errors. I'm referring to the small shop making brackets for a wire harness for aircraft, maybe a small machine shop fabricating a fitting for an airhose on board a ship. They all are important, but the wild goose chase some of these big companies will send you on just to satisfy some 4,000 employee company's idea of cause and corrective action is not justified. They have the personnel who can spend a week looking for the boogie man, and he/she won't be missed. If it's the same part, same excuse, well look deeper. If it's not, do your best to find the cause and get on with life. I still think that most of this stuff is directed from the bully pulpit. Yup, this is energy working at home, so I crafted a similar user name. Can I use my user name on my home computer or am I commiting "Operator Error"?

Jim Evans

I am one of those that will not (under any circumstances) buy "operator error" as a root cause of a problem. It tells you nothing about the nature of the problem other than an operator was involved. Laura is correct in that you need to ask why (as many times as needed) to get to the root cause. Even in the second scenario that Dan cites if the correction was to mistake proof the process then the design of the process that allowed the operator to insert a part in bacwards (or whatever the problem) was the root cause.

Tradionally "operator error" has been the dumping ground for all sorts of problems that company managements did not want to accept the responsibility for because it was their systems that were at fault. I would say that most companies that I deal with will not accept "operator error" as a root cause.

Best Regards,

Jim Evans

Michael T

Ok.... I guess I have to play devil's advocate here....

If we say that "operator error" is not an acceptable root cause, how much can we "mistake proof" the process before it becomes financially untenable?




If you don't care for the term "operator error", you really wouldn't enjoy "unknown".
We used it when there was no way to pin down the cause. Talking with all personnel in the loop, no legitimate cause could be determined. We had 15/18 operations where nicks and scratches could have ocurred. Nobody in the process could point to the cause. We used "unknown", with separating the parts with dividers to eliminate normal handling. That's alot more honest then blaming an Operator. If it's Operator Error, that's the cause. With 40 operators, and not always the same one responsible, it's hard to believe it's a training issue. You can say it, but that don't make it so. It also has to be mentioned that the company's PPM defects didn't even show on the customers' quarterly report. So the customer had to change to report to show units on the graph to a max of 10. Then we can see 5 pcs rejected out of thousands shipped. Think about it. 1500 pc order with one pc having blurred part marking. Another 2000 pc order with a scratch on it. This with an approved sampling plan for final inspection. The amount of time required and the futility of determining who, what and where, just doesn't "add value". Most importantly, the orders kept coming. It's not a perfect world and some customers that know you provide superior product are aware of it. Once more, Customers that demand full blown investigations in light of the conditions I mentioned, employ way too many Quality Geeks with not enough work to do. They are just feathering their nests and beating their inflated chests because as the Customer, they can. I want to add that the average cost per part is about $2 or $3 each, with the customer continuously trying to nickel and dime that cost down. Some parts aren't even a $1. Give me a break!

[This message has been edited by energy (edited 08 May 2001).]

Dan Larsen


In your example, I don't know that the cause is unknown as much as the source. The cause is high potential for mishandling; your solution was appropriate for the problem.

I also sympathize with you regarding the PPM issue. In fact, it can be frustrating when customers issue CAR's over what seem to be petty issues.

There seem to be quite a few companies that issue CA's for every reject or concern regardless of the significance. When this approach is used, it diminishes the impact that a CA should have, the result generally being that root cause analysis suffers.

Personally, I think CA systems are one of the most misused systems in ISO and QS. I guess that's one reason they tend to be such a hot topic.
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