To Err Is Human

Online Reprint

Often when an incident happens, at the end of the day it’s attributed to “human error.” But what IS human error? Is someone cutting away a perfectly good canopy the same type of mistake as turning to final way too low to the ground? Is someone going to rears on a BASE canopy when they want more glide the same kind of human error as misrouting a bridle?

Don Norman is famous for popularizing the idea of human-centered design, a design framework for developing solutions to problems while keeping the human perspective at the forefront. What this really means—and where it applies to air sports—is that you can’t separate analyzing a situation (that involves humans) from human psychology. So rather than lumping all the ways humans fuck up into one grand mess of “human error,” you learn a bit more about how brains work and nervous systems respond and you learn to tease apart the many disparate ways that we meat-sacks can fail.

Then you use that information to get better.

Chapter 5 of Norman’s famous book “The Design of Everyday Things” is called “Human Error? No, Bad Design” and discusses the psychology of human error. Human error is defined as any deviance from “appropriate” behavior. The word appropriate is in quotes because often the appropriate behavior is not known or is only determined after the fact.

When something bad has happened, people inevitably want to know why. But too often, they’re satisfied when they get a shallow answer. “The tendency to stop seeking reasons as soon as a human error has been found is widespread,” writes Norman.

“Why did he front-riser himself into the ground?”
“Because he was trying to swoop and fucked up.”

Photo courtesy Skydive Midwest.

“Why did she end up with a CYPRES fire?”
“Because she forgot her pull priorities.”

Neither of these answers is enough. To get at the root cause, Norman recommends using the Five Whys method, developed by Sakichi Toyoda. It’s exactly what it sounds like: you will usually need to ask “why” at least five times before uncovering the true underlying cause of an incident.

“Why did she die?”
“Because she had a container lock.”
“Why did she have a container lock?”
“Because she misrouted her bridle.”
“Why did she misroute her bridle?”
“Because she was packing in a hurry.”
“Why was she packing in a hurry?”
“Because she was trying to catch up with her friends so she could jump with them.”
“Why was she trying to catch up with her friends?”
“Because she was uncomfortable jumping by herself.”
“Why was she uncomfortable jumping by herself?”

And so on.

It can take a lot more than five whys.

Finding the real root cause matters. As Norman writes, “When someone says, ‘It was my fault, I knew better,’ this is not a valid analysis of the problem. That doesn’t prevent its recurrence.” Without digging deeper, we can’t prevent ourselves—or others—from making the same error.

So what kinds of error are there? Norman divides error into two major categories: mistakes and slips.

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A slip occurs when a person intends to do one action and ends up doing something else. The correct action is known and intended, but not performed.

Action-based slips are where the wrong action is performed. It’s the kind of situation where you throw your coffee mug on the bed and try to drink your cellphone; or where you’ve practiced your emergency procedures so much that at pull time, you immediately cut away and pull your reserve without meaning to, from sheer muscle memory.

Memory-lapse slips are where the intended action is not done or its results not evaluated. You get carried away in conversation while packing and forgot to set your slider.

Both kinds of slips happen subconsciously and you’re susceptible to them when you get complacent.

A mistake occurs when the wrong goal is established or the wrong plan is formed. From that point on, even if the actions are executed properly, they are part of the error because the actions themselves are inappropriate.

Rule-based mistakes are where the problem or situation is correctly diagnosed but an erroneous course of action is chosen; a wrong rule is being followed. You’re jumping at a new DZ at a much higher altitude but you follow the “rule” for flying your canopy back at your home DZ, which is 20 feet above sea level. You’re taking a rule for one situation and overlaying it on another situation inappropriately.

Knowledge-based mistakes are where the problem is misdiagnosed because of erroneous or incomplete knowledge. You take someone else’s word for an object’s height and end up choosing the wrong delay for the object.

Memory-lapse mistakes take place when there is forgetting at the stages of goals, plans or evaluation. You forget about the micro weather patterns in late afternoon at your local mountain and fly your paraglider into a bad situation. (The difference between this and a memory-based slip is that with a slip, you fully intended to do the right thing. With a mistake, your intentions, somewhere along the way, were bad or wrong. Mistakes result from conscious choices and deliberations.)

Interestingly, Norman writes, “Slips tend to occur more frequently to skilled people than to novices, because slips result from a lack of attention to the task. Skilled people—experts—tend to perform tasks automatically, under subconscious control. Novices have to pay considerable conscious attention, resulting in a relatively low occurrence of slips.”

When you’re a newer skydiver, BASE jumper or paraglider pilot, you’re at risk of making many different types of mistakes. But as you gradually gain mastery of your discipline, slips become the enemy. You get complacent and you make an error despite fully knowing better.

The next time something goes wrong, try applying this framework to the incident and see if it helps you understand what happened. You can also use the framework to try to prevent errors. When you’re performing an activity in which you don’t have complete mastery, ask yourself: is there anything about this situation that’s different from the usual? Might I be applying a rule from another situation onto this one inappropriately? Is there any knowledge I might be lacking? Is there anything I’ve forgotten when I’m making my plan or choosing my goal? Asking a trusted and more experienced peer can be a good way to identify mistakes.

Then, when you’re more experienced and realize that you’re starting to feel comfortable, check yourself again. Realize that your experience is opening you up to a whole new kind of error. Bring a little more consciousness and deliberation back into your process in order to avoid slips.

Remember: we’re never going to eliminate our human tendency to make errors. But that doesn’t mean you have to be the one making them.