Category Archives: Latent Error

How should we address media stories about potential human error?

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Rule number one when performing any human error event-investigation is to not jump to conclusions based on what you know at this moment. This gets really tricky when your experience leads you down a path, and people really want you to immediately weigh in on the topic (this is where the news media sometimes gets it wrong). Consider the post that spoke about the Jenga tower and how we look at things after an event happens. Case in point: recently a roller-coaster in Texas had a customer fatality (click here and here for story) and I have been asked to comment (not by media, but by family and friends). This type of questioning happens all the time when news-worthy tragedy states anything regarding what seems like human error in some way, shape, or form. The questions are not serious inquiries, but do challenge your reputation as being an expert at what you do. I get google alerts on potential human error almost every day in my email to keep up with unwanted outcomes in the news. I really try to stay on the proactive side of preventing events, and assist root cause analysis experts as they investigate, because you really need to understand the architecture of an event to develop corrective actions ensuring it can never happen again. I do my best to understand the human elements (including distractions, experience, and decision making) involved, but the equipment-related issues, typically are beyond the scope of my involvement.

Is there a paradox here? I will ask you an open question I no longer wonder about: Why are typically more people employed to investigate events than people trying to prevent them? (for example, there may be an entire Corrective Action Program department, but only one dedicated Human Performance person). We’re all trying to prevent them…. right? Maybe it’s a bad question to ask, as long as someone is training, tracking, and trending, the rest of the organization will keep trying to prevent them, as well. In nuclear power we have many trainers, and multiple department personnel who help to identify, track, and trend errors. This is never a singular effort by any means, so I conclude that more people are employed to reduce or eliminate events than to investigate them, but sometimes they need to be reminded of that duty.

How can you be an expert if you have no opinion?

We need to establish a balance between being an expert at what we do, and giving assumptions to people inquiring. It can be really hard to do when people are looking to you for some type of initial comment or resolution to something that is tragic. People have a natural tendency to look for an answer so they can go on with their lives, believing this situation was a fluke and it has no bearing on their current or future lives.

Supplying answers based on limited (and potentially incorrect) information provided by public and social media is still jumping to conclusions. We want to give answers, but it’s often too soon to derive an official explanation that would be palatable to the masses and the critics. I understand nobody is looking for an insurance investigation report, but it would still be nice to provide anyone who asks us questions about the event some semblance of our expertise, wouldn’t it?

What we know at the point after any event is something was different this time, and we need to analyze the variables and the points leading up to the failure. One of my favorite authors and speakers, Sydney Dekker, stated that we have to find out why the person’s actions made sense to them at the time they made them, because they would not make the same decisions knowing what the outcome would be. Things are always more clear looking back on an event with a broader and less focused mindset than beforehand. Investigators need to find out what system failures led up to the event, what personnel contributed to the outcome and where any negligent culpability may be.

Okay, but can you say anything at this point in time?

Breaking down what appears to be one of two kinds of error: Latent or Active… Latent error may be the interlock in that roller coaster car was failing (fatigue) and finally let go, where an Active error would be that the interlock wasn’t properly engaged prior to the ride starting, either by the operator or the guest. Another Active error would be to start the ride prior to ensuring all of the guests were locked in properly, and many operator distractions could play into that – lack of experience, life events, or any other typical distraction. From my experience summer-time ride operators are typically teenagers, too, and they may not fully understand the responsibilities they have for ensuring rider’s safety, and thus be less engaged than we would hope. Another Latent issue may be the culture of the people operating the ride – are they always working with the customer’s safety in mind by being diligent and a bit slower, or do they take shortcuts to cycle as many people through the ride as possible, because that’s what is measurable and perceived by management as priority one, even if they preach safety?

The painful truth: Amusement rides are designed for average people sizes, and almost all have height restrictions (as many little people have been frustrated with), but we don’t always have restrictions for people too big. In Florida at Universal Studios and Walt Disney World I’ve personally seen and tried out sample roller coaster chairs for people of all sizes to test out prior to getting on a major attraction. Mainly to avoid the embarrassing conversation from the operator that you are too big (or potentially too small) for the ride you just waited 10-60 minutes to ride on, but also (and most importantly) to make sure you fit so you can be as safe as possible throughout the thrill-ride.

The possible second victim(s)

If you caught my earlier post on this subject, you may be aware that the ride operator, culpable or not, may be feeling blame for the loss of the life involved in the above roller-coaster tragedy. This person most likely will be removed from their duties pending the police and insurance investigation. Keep in mind that workers involved may not have done anything wrong or incorrect by park procedure. We simply do not know until the investigation is concluded.

A very personal story from my childhood

The summer I turned 11 (1983) I was a week away from starting football tryouts for the Dolcom League in Groton, CT. My Dad was on shore-duty finishing up his 20+ year-long career in the U.S. Navy, and thought it would be a great weekend to take my sister and I to Riverside Park (now called Six Flags New England in Massachusetts).

We were hitting all the rides (my sister and I were professional thrill riders) and my parents thought we should take a break for pizza, a family favorite. We set our food down in the picnic area and ate quickly as my parents relaxed and ate at a more mature rate. My sister and I asked if we could go on a nearby ride called, “The Rotor” while they finished up lunch. They complied and off we went.

The concept of the ride is you go through a door into a vertical cylinder where you stay standing and the cylinder spins pretty fast – the floor drops down a couple of feet after you stick to the wall through centrifugal force and then eventually, the ride slows down and you slide to the floor below – the operator then asks for everyone to get to the center of the floor (you are very dizzy at this point) and then they bring the floor back up to the door level and you get out. Author’s note: If you’ve been on the ride in the last 20 plus years, you may remember that it works differently now.

After we had slid down the walls, we were asked to gather in the center of the floor… as the floor was rising a woman, presumably dizzy, bumped me and I balanced myself by putting my right foot against the wall so I didn’t fall down… the operator wasn’t paying enough attention to stop it immediately and the floor grabbed by nike cloth sneaker and wouldn’t let go… My parents heard my scream from the picnic area and knew something was very wrong with me… the operator eventually stopped the floor from coming up after the scream and everyone yelling for the floor to go down (the operator looks in from the top). My foot was fractured (“smushed” is how I would describe it) and I was on crutches for many challenging weeks. The numbness in the top right quadrant of my foot took two years to heal, but it did fully recover. Not soon enough to play football though.

I have seen this ride in different parks and have learned of corrective actions put in place to prevent this type of accident from happening again – i.e. the floor goes down only a few inches after you stick to the wall and then comes back up before the ride slow down. With this change in process, the operator can actually be less attentive with less opportunity for an event. Interestingly enough, in Essex (overseas), the ride is very similar to the 1983 ride I took. When my kids get older and ask me to go on this type of ride what do you think I will say?

Some random recent potential human error media examples:

Human error cited in fire boat incident

Human error still major cause behind road crashes on South African roads

French minister: Human error not behind train crash

Bottom line advice

Don’t allow people to jump to conclusions and advocate for the investigators revealing the causes and contributors.