Tag Archives: accident

Root Cause Analysis - Incident Investigation

The 8 Worst Typos Ever Made

By ThinkReliability Staff

When we perform a root cause analysis, we occasionally find that something as seemingly minor as a typo has had a huge impact on an organization’s bottom line, their reputation, or even public safety.  The following is a collection of some of the worst typos ever made, with respect to impacts to the organization’s goals.

8. Misspelling your own name 

The Oops: In 2008, a New Hampshire newspaper misspelled its own name, in the front page title, specifically by adding an extra “s”.  Missouri State University misspelled its own name on bags provided to students (Univeristy [sic]).  The error was pointed out by a student.  However, the most well-known of this kind of error probably occurred when “Chile” was misspelled on their 50-peso coin.  The misprinting occurred in 2008, but was not noticed until late 2009.  (Rather than CHILE, the coin said “CHIIE” [sic].  The coins are now collectors’ items.)

The Impact:  The general  manager of the Chilean mint was fired for the coin error.  In the newspaper and university cases, actual cost was minimal and the main impact was abject embarrassment.  However, typos can frequently result in loss of opportunities.  Some recruiters have said that when they get multiple submissions for a single job, resumes with errors go straight to the shredder.

7. Counting on a computer to do your job for you 

The Oops: On January 7, 2009, the US Army admitted that 7,000 letters addressed “Dear John Doe” were sent out to family members of soldiers killed in Iraq.

The Impact: The Army immediately issued a formal apology and sent a personal note to the families.  The letters were sent to the correct families, but there must have been a devastating moment for the families when they thought they may have received someone else’s letter . . . and then realized they hadn’t.

6. Entering the wrong number 

The Oops: On February 5, 2011, an employee at a company in Japan listed 610,000 shares of a job recruiting company at 1 yen apiece.  What it really meant to do was list 1 share at 610,000 yen (~$5,000).  A surprising number of similar stories abound, including a listing on April 5, 2006 for flights from Canada to Cyprus for $39 CAD, instead of $3,900.

The Impact: Although the company in Japan tried to cancel the order, it was processed by the Tokyo Stock Exchange, resulting in a loss of $225 million.   In the case of the surprisingly cheap airline tickets, they were honored by the airline (after initially trying to cancel the tickets) to 500-2000 people, resulting in a very expensive typo indeed.

5. Incorrect punctuation 

The Oops: A communications company in Canada thought it had a five-year deal beginning in spring 2002 with a utility company to add cable lines to thousands of utility poles.  Then the utility company cancelled in early 2006.  The Canadian Radio-television and Telecommunications Commission determined that, because of an extra comma, the contract said that the contract could be cancelled with one-year’s notice, even during the first five years.  (The area in question said the contract: “shall continue in force for a period of five years from the date it is made, and thereafter for successive five year terms, unless and until terminated by one year prior notice in writing  by either party.”)  A missing hyphen in the coded computer instructions was partially responsible for the loss of steering on Mariner 1, which was launched on July 22, 1962.

The Impact: After the cancellation, the utility upped its rates for the use of the poles, which will result in the communications company paying about $2.13 million more than it thought.  But if you think that’s expensive, even worse was the loss of Mariner 1, which had to be blown up when it could no longer be steered.  The value of the Mariner 1 in 1962 was $18.5 million.

4. Using the wrong units 

The Oops: The Mars Climate Orbiter was lost on September 23, 1998 while trying to establish orbit around Mars.  Turns out the trajectory was lower than expected (allowing the orbiter to be subjected to the extreme heat of the Martian atmosphere) because incorrect velocity changes were used in calculations.  Specifically, results from a software program were provided in pound force (English System of Units) and the program predicting the velocity assumed the results were  in Newtons (International System of Units, or SI), a factor of difference of 4.45.  (Read more about the Mars Climate Orbiter.)

The Impact: The Mars Climate Orbiter was destroyed with a complete loss of mission.  The orbiter cost $125 million in 1998.

3. Leaving out a (very important) word 

The Oops:  The interesting thing about some small words (like “not” or “out”) is that they change the meaning of the entire sentence.  A man named Bruce Wayne Morris (who does not become Batman) was sentenced to death in 1987 after the jury was given the choice of death or prison for life with the possibility of parole.  The choice was in fact between execution or a life sentence without parole.

The Impact: Morris’ death sentence was reversed by a federal appeals court in 2001 – that’s right, 11 years later.  (The cost of 11 years worth of deliberation and appeals is not known.)  It is thought that the jury originally opted for the death sentence rather than worrying about him being released on parole at some point in the future.

2. Checking the wrong box 

The Oops:  On January 28, 2013, Evan Spencer Ebel was released from jail, the result of a clerical error.  In 2008, while serving eight years, Ebel pleaded guilty to assaulting a prison guard.  The additional sentence was to be served after the original eight-year sentence.  Instead, the record indicated that the second sentence was to be served concurrent with the original sentence.

The Impact: Ebel is believed to have murdered a pizza delivery man on March 17 and the executive director of the state Department of Corrections on March 19 before he was killed by deputies in Texas on March 21.  A similar situation also ended in tragedy when Charles Anthony Edwards III was mistakenly discharged  in January 2012 from a high-security mental hospital in California, where he is suspected of fatally stabbing a shop owner.

1. Writing illegibly 

The Oops:  While bad penmanship may not necessarily be considered a typo, it can result in the same kinds of problems.  Bad penmanship means that the person who has to read it is much more likely to read it incorrectly.  In one such case, the registration for a ship’s Emergency Position Indicating Radio Beacon (EPIRB) was written sloppily, and a “C” become a “0”.  This didn’t much matter until more than two years later, on March 24, 2009, when the ship (Lady Mary) began to sink and set off its EPIRB.  Because the code was entered incorrectly, it took more than an hour and a half to locate the ship.

The Impact: By the time the Lady Mary was reached (the delay was due to other compounding errors as well), only one crew member was able to be saved.  The other six men were lost at sea.

What to do so this doesn’t happen to you 

When something is important, give it an extra edit.  Specifically, find someone who is not a coworker (a coworker will likely gloss over the same things you did, like the name of your organization).  Motivated teenagers make great editors.  Offer them a dollar for every error they find.  (It’s well worth it.)

Note that legal documents, given the importance of their exact wording and difficulty changing any whoopsies, should be extra, extra carefully edited.

If you really don’t have time to get an independent edit, try reading it out loud.

When your computer is doing some of the work for you, it’s probably a good idea to actually look at a few of the results.

When you’re working with numbers, which are much more difficult to check for errors than words (“univeristy” [sic] is not a word, but 39 is still a number), perform a related math calculation.  One that in particular could have come in handy here is the percentage reduction in the cost of the item.   (Plane tickets at 99% off?  Maybe you want to look at that one again.)

Also, your math teachers weren’t kidding about always using units with your numbers.  Or else you might as well answer the question “How far is it?” with “10”.  If at any point in your analysis a different unit of measurement comes up, go ahead and write both, the way many cookbooks and measuring cups now contain both ounces (English System of Units) and milliliters (Metric System of Units).

All the editing tips above may help, but maybe more important is an understanding of the possible impact of a seemingly innocuous typo.  Yes, they happen to everyone.  But before you let them out of your office, take another look.  If someone thinks you’re wasting your time, show them the two million-dollar examples above.

I’ve made a handy sheet to remind you why you care about editing.  To take a look and print it out for your wall, please click “Download PDF” above.

Root Cause Analysis - Incident Investigation

Seat Belts: A Simple Solution That is Still Underused

By ThinkReliability Staff

One of the most frequent questions we get is “What’s the root cause?”  The problem with that question is that there is never just one, root cause.  Rather, the ‘root cause” should be thought of as a system of causes, much like the roots of most plants are a system.  But the idea of a root cause is attractive – only one thing to find, analyze and solve.  There are a few, rare situations that are almost one, root cause.  One of them is the use of seat belts.

Not wearing a seat belt can cause all kinds of problems, in any kind of vehicle.  In passenger vehicles, seat belts saved more than 75,000 lives from 2004 to 2008, according to the National highway Traffic Safety Administration (NHTSA).  Over that same period, more than 26,000 more lives WOULD have been saved if everyone wore a seat belt.  Unfortunately, not everyone does.  According to the National Safety Council (NSC), seat belt use varies by the type of vehicle but is around 80%.

It’s not just cars that are at issue.  On March 29, 2013, a man was thrown from an experimental plane and killed when the canopy came off.  He wasn’t wearing a seat belt, which would have almost certainly kept him from being ejected – and killed.  Although the FAA requires that safety belts be fastened while crewmembers are at their duty  stations, the pilot, who was killed, had unfastened his safety belt to troubleshoot problems with the battery and apparently did not successfully re-fasten the belt.   (The instructor was not ejected and was able to safely land the plane.)

Although states are trying with mandatory seat belt laws, you can’t force everyone to wear a seat belt all the time.  However, there are many actions being taken to try and increase seat belt use.  As previously mentioned, states are increasing laws and enforcement of requiring seat belt use for all passengers.  Car manufacturers have added warning systems that encourage seat belt use for drivers, and front seat passengers.

Seat belt use (percentage-wise) is lowest among those who have just gotten their license.  As a parent, requiring use of a seat belt every time, every trip, for every passenger can help reduce the risk to your child and his or her passengers.  As an employer, vehicle crashes can have a serious impact to your organization. According to the Occupational Safety and Health Administration (OSHA), motor vehicle accidents are a leading cause of death and injury and cost employers $60 billion annually.  All employers should have a driver safety program.   (Tips on establishing a driver safety program can be found here.)

There is no question that deaths from traffic accidents are a major concern – to everyone.  According to the NHTSA, “seat belts are the most effective traffic safety device for preventing death and injury.”  Because of the effectiveness of seat belts, the  risk of deaths from vehicle accidents, it’s no stretch to say that buckling your seat belt – and getting everyone in your vehicle, family, and organization to do the same – may well be the most important thing you do today.

To view the Outline and Cause Map for the plane ejection, please click “Download PDF” above.  If you’re curious why school buses do not have seat belts, read our previous blog.  Or click here to  read more:

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Root Cause Analysis - Incident Investigation

8 Marines Killed During Training Exercise With Live Ammunition

By ThinkReliability Staff

Eight Marines were killed, and seven Marines and sailors were injured, as the result of the unexpected explosion of a 60 mm round inside a mortar tube during a live ammunition training exercise.  While details are still to be determined, it is known that the unexpected explosion of a mortar round led to the deaths and injuries of those participating in a training exercise with a 60 mm round inside a mortar tube.

Though details of the incident are still unknown, we can begin a Cause Map, or visual root cause analysis, diagramming possible causes which remain to be investigated.  As more information becomes available, evidence supporting or excluding potential causes is included on the Cause Map.

We capture the What, When and Where of the incident in the Problem Outline.  In this case, a training accident/ explosion occurred on March 18, 2013 at about 10:00 pm at the Hawthorne Army Depot in western Nevada.  At the time, a mountain training exercise with live ammunition was using a 60 mm round inside a mortar tube.  A traffic accident that may be related has been mentioned in the news, but no detail has been provided.  To ensure that this line of inquiry is followed during the investigation, we can include it in the “different, unusual, unique” line of the problem outline.

Data that is known, such as the types of damage resulting in deaths and injuries, is included with supporting evidence, in this case testimony of the hospital spokesman.  Causes still to be determined, such as whether the mortar round exploded prematurely in the tube, detonated after being fired, or whether more than a single round exploded are included with question marks and joined by “OR”.  When evidence is obtained throughout the investigation related to a given cause, it is included directly beneath the cause it controls.  Along with the unknown method of detonation of the round, it is unknown whether an issue with the firing procedure, a malfunctioning firing device, or a malfunction in the explosive mortar is to blame.

More details should be coming soon since the use of 60 mm mortars is suspended until the review of this incident determines what happened.  At that time, those causes ruled out by evidence can be crossed off (but left on the Cause Map so that others know they were considered and ruled out as more evidence became available).

At that time, solutions that best address the issues that were causally related can be brainstormed, evaluated, and implemented.

To view the Outline and Cause Map, please click “Download PDF” above.  Or click here to read more.

Root Cause Analysis - Incident Investigation

Brazilian Nightclub Fire Kills At Least 238 People

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By ThinkReliability Staff

A pyrotechnics display meant for outdoor use turned deadly at a band concert in a nightclub in Brazil on January 27, 2013.  The pyrotechnics – which were set off by the band – lit the soundproofing on the ceiling and it spread – with little help from non-functioning fire extinguishers.  The large crowd had difficulty leaving the club, which had only one exit blocked by bouncers who thought patrons were trying to leave without paying.

This tragic incident can be examined using a Cause Map, or visual root cause analysis, which visually diagrams all the causes and impacts related to the nightclub fire.  We begin with the impacted goals.  The safety goal was impacted due to the at least 238 people who were killed and 100 who were injured.  The severe fire is an impact to the environment.  People were unable to exit, which can be considered an impact to the customer service goal.  The loss of the use of the nightclub is an impact to the production goal, and the damage is an impact to the property goal.  Additionally, members of the band and owners of the nightclub are being held, potentially to be charged with manslaughter.  This can be considered an impact to the employee goal.

We begin developing cause-and-effect relationships by asking “Why” questions.  People were killed because they were in the nightclub, unable to exit and there was a severe fire.  Questions have been raised about why the nightclub was even in operation, as its licenses were expired.  People were unable to exit because there was only one exit – completely insufficient for a facility of this size and no windows in the bathroom.  Bouncers were blocking the only exit because they believed patrons were trying to leave without paying – nobody had told them of the fire.  Difficulty seeing the exits due to smoke and lost power resulting from the fire complicated matters even more.

The fire began when the pyrotechnics (heat) lit the soundproofing on the ceiling (fuel).  The fire was unable to be put out due to difficulties reaching the ceiling and non-functioning fire extinguishers.  Specific solutions are being debated by lawmakers in Brazil, but it is hoped that this tragedy will draw attention to – and improve – some of the conditions that contributed to this tragedy.

To view the Outline and Cause Map, please click “Download PDF” above.  Click here to read about another building fire.

 

Root Cause Analysis - Incident Investigation

Commuter Ferry Crash in NYC Injures 85

By ThinkReliability Staff

A commuter ferry struck a pier in Lower Manhattan, NY during the morning commute on January 9, 2013, injuring at least 85 people – some critically .  According  to US Coast Guard Captain Gordon Loebl, “We know that they hit the pier at a relatively high rate of speed.”

We can examine this issue in a Cause Map, a form of root cause analysis which provides a visual “map” of cause-and-effect relationships.  We begin by determining the impacts to the goals resulting from this incident.  The safety goal was impacted due to the large number of people who were injured.  (No fatalities have been reported as a result of the crash.)   The customer service goal was impacted because the ferry slammed into a pier (nobody expects that on their morning commute!).  The ferry was damaged, impacting the property goal.  Presumably the ferry will be out of service for some time, impacting the production goal, and will require repairs, impacting the labor goal.  Any time required for the response can also be considered an impact to the labor goal.

A Cause Map can begin as simply as beginning with an impacted goal and asking a couple of why questions.  In this case, the safety goal is impacted by the injuries, which were caused by the ferry striking the pier.  More detail can be added to the Cause Map by asking more “Why” questions.

In this case, it’s not clear what caused the crash, though drug or alcohol use by the captain has been ruled out.  There have been some recent complaints about maneuverability due to a recent overhaul replacing the engine and propulsion system but it’s not clear if this played a role in the crash.  It’s also unclear why the ship was traveling at 14 knots when it was about to dock.  Because the ship was about to dock, people had gotten up from their seats and were standing in hallways and on or near stairways, increasing the rate of injury.  It does not appear that there are any regulations requiring commuters to remain seated until the ferry has stopped moving.

The ferry company, as well as the appropriate transportation authorities, will continue their investigations to determine the causes of the ferry incident.  Once they do, they will provide recommendations or requirements to ensure a safer morning commute.

To view the Outline and Cause Map, please click “Download PDF” above.  Or click here to read more.

Root Cause Analysis - Incident Investigation

Deadly Superstorm Slams the US

By Kim Smiley

Hurricane Sandy pummeled the Mid-Atlantic region of the United States on October 29th  and 30th, 2012, leaving more than eight million people without electricity, causing massive flooding and killing over 110 people.  The damage done by this storm was massive and economic impacts have been predicted to be as high as 50 billion dollars.

Why was Sandy so devastating?  This question can be answered by building a Cause Map, an intuitive format for performing a root cause analysis.  A Cause Map is a useful tool for breaking down this complicated issue and can help explain why this storm was unique.

In this example, there are a number of things that combined to made Sandy a unique and especially dangerous storm.  First off, Sandy wasn’t just a normal hurricane.  As hurricane Sandy moved to the north it converged with other weather systems turning into a hybrid storm.  This hybrid storm brought with it a combination of extreme summer weather (strong winds with heavy rains) and winter weather (cold temperatures and snow).  Unusual timing of the different weather systems helped this superstorm form.  Hurricane Sandy hit very late in hurricane system and cold air sweeping down from Canada was colder than typical for this time of year, a combination that proved deadly.  The nature of these converging weather patterns also made Sandy a very slow moving storm so that areas experienced higher rain fall and more damage than they might have with a faster moving system.

Normal hurricanes are powered by the warm, moist tropical air and weaken as they travel north.  They also typically turn to the right and head out to sea.  When Sandy converged with the other systems it became an extra-tropical cyclone and actually strengthened as it hit shore.  The effects of these other weather systems also turned the storm left onto land and it took an unusual path over some of the most heavily populated areas of the US, including NYC,  intensifying the impact of the storm.

The timing of Sandy also impacted the peak flood levels.  Sandy hit during a full moon when tides are at the highest point of the month.  During a full moon, the effects of the moon’s gravity are felt the strongest so tides are higher.  The high winds created by Sandy combined with the full moon resulted in a massive storm surge.

Sandy truly was a Superstorm.  Weather systems that normally don’t exist at the same time converged to create a massive storm that moved in a usual path over one of the most heavily populated regions in the US.  And the storm hit at the worst time of the month for flooding.

For more information click here or here.  To view a high level Cause Map of this issue, click “Download PDF” above.

 

Root Cause Analysis - Incident Investigation

The Comet That Couldn’t Fly

By ThinkReliability Staff

“… the most exhaustively tested airplane in history.”

-Expert opinion on the DeHavilland Comet

Today, commercial jet air travel is standard fare. Estimates for the amount of air traffic over the United States in a given day have been in the range of 87,000 flights. With clever planning, clear skies and smooth service, a citizen almost anywhere in the world can get anywhere else by plane in less than 24 hours. But looking back at the history of aviation show us how far safety has come. Consider the DeHavilland Comet, the first commercial jet to reach production. British aviation specialists finalized the Comet’s design with much excitement in 1945 in hopes it would position their industry to establish a revolutionary service in commercial jet flight. Unfortunately, the Comet crashed on January 10th and April 8th in 1954.

What happened? We can identify some of the causes in a Cause Map, or visual root cause analysis.

CAUSE #1: POOR TESTING When you test an extremely heavy object carrying hundreds of people at high speeds thousands of feet above the ground, you would think planning for the worst case scenario would make the most sense. Unfortunately, the Comet tests were performed in tainted conditions on the strongest part of the plane.

Add in the fact that there was no prototype for the plane and you’ve got a test not worth having… and a plane not worth flying.

CAUSE #2: UNEXPECTED PRESSURE Altitude leads to pressure, and pressure puts stress on planes. But this stress wasn’t evenly distributed, and certain parts of the planes’ bodies were unevenly affected. So rather than the expected amount of pressure on the planes, the Comets faced an unforeseen squeeze.  

CAUSE #3: FLYING ABOVE AND BEYOND The Comet flew at twice the speed, height and cabin pressure of any previous aircraft, displaying a rather dangerous amount of ambition.

Combine all of this, Cause Map it, and you’ve got a plane flying under incredible conditions it couldn’t withstand, facing high pressure where it was most vulnerable.

In other words, an airborne recipe for disaster.

FALLOUT #1) SAFETY As expected, the pressure cycle in the planes’ cabins cracked the bodies of the planes. When the planes broke up, the lives of 56 passengers and crew members were lost.

#2) CUSTOMER SERVICE Some British industry institutions have a highly prestigious reputation (the Royal Navy’s impact on British sea travel comes to mind). The loss of the aircraft, though, was a black eye on British Aviation. Aviation historian George Bibel called the Comet an “adventurous step forward and a supreme tragedy.”

#3) MATERIALS/LABOR Effective airplanes have never been cheap, and this was no different. Not only would it cost money to investigate the cause of the accidents, but to replace the airplanes.   

FUTURE SOLUTION The Comet’s tragic crash had one silver lining: the post-crash analysis performed by its designers (including Sir Geoffrey de Havilland) set the precedent for future air accident investigations. In fact, the Comet was redesigned to solve the issues that caused the crashes and would later fly successfully. But by then, Boeing had already taken over most of the commercial jet market.

In the end, the Comet was first in flight but last in the market.

See more aviation cause maps:

Want us to cause map a specific plane crash for you? Tell us in the comments and we’ll pilot our way through it.

Root Cause Analysis - Incident Investigation

The Dangerous Combination of Hot Cars and Children

By Kim Smiley

Every summer, the news covers heartbreaking stories of children who die after being inadvertently left inside a vehicle.  Since 1998, 527 children have died from heat stroke from being exposed to high temperatures inside a vehicle.  One of the most tragic elements of these stories is that these deaths are preventable.

This issue can be analyzed by building a Cause Map, a visual root cause analysis that intuitively lays out all the causes that contributed to the problem. The first step in building a Cause Map is to determine how the issue affects the overall goals.  In this example, the safety goal is the obvious focus since there have been hundreds of deaths.  The next step is to ask “why” questions and add the answers to the Cause Map.  Why have 527 children died?  They died of heat stroke because they were left inside a car and the interior of the car was hot.  Children also overheat quicker than adults because their thermoregulatory system isn’t as efficient.

The children were left inside the car because they were inadvertently forgotten, a caregiver intentionally left them inside or the children managed to get inside the cars themselves.  There are a number of reasons that a caregiver could forget a small child. The most frightening thing about these incidents is that it can happen to well intentioned, loving parents who simply make a terrible mistake.  These incidents tend to occur most often when there is a change of routine, such as a different parent than normal doing the daycare drop off.  It certainly doesn’t help that many parents and caregivers of young children are tired and potentially sleep deprived. The driver may also not be able to see a small child because many states require backward facing car seats in the back seat.   In the cases where a caregiver intentionally leaves a child and no harm was intended, it’s safe to assume that they didn’t understand the danger.  There are also cases where a child enters a car and becomes trapped inside.  In those examples, the vehicle was most likely unlocked and the caregiver didn’t realize the child was playing in the vehicle.

Vehicles are  especially dangerous because they heat up very quickly to dangerous levels.  A car is an enclosed space with a lot of windows to let in sunlight, making it an ideal situation for temperatures to increase.  Even relatively mild days can result in hot temperatures inside a car.  The temperature inside a car can raise about 40 degrees even when the ambient temperatures are in the 70s, meaning the inside of a car can be over 110 degrees on a fairly cool day.

There are a number of gadgets people have invented to help prevent children from being inadvertently forgotten in a car, but their effectiveness is debated.  The simplest way to prevent this from happening is very low tech; put your purse, shoe or anything that you must have in the backseat.  Another suggestion is to keep a large stuffed animal in the car seat and then move it up to the front passenger seat while the car seat is occupied so that you have a visual reminder of your precious cargo.  The most important thing is to be aware of this deadly problem and have a plan to prevent it if you ever drive around children, especially those strapped into car seats.

Root Cause Analysis - Incident Investigation

Slips, Trips and Falls: A Root Cause Analysis Primer

By ThinkReliability Staff

Slips, trips and falls happen every day.  Falls are responsible for tens of thousands of deaths each year.  (Slips and trips are considered a subset of falls, and are included in these numbers.)  Falls on the job account for 12-15% of all worker’s comp costs.  The direct and indirect costs of workers injured and killed on the job are estimated to be billions of dollars each year, both in worker’s comp claims and in lost productivity.  In 1999, as an example, 5,100 workers were killed by falls and over 570,000 injuries were reported.  However, there are many things that can be done to prevent and lessen the impact of falls.  Performing a Cause Map, a visual root cause analysis, will allow us to identify all the potential causes of falls.  A thorough root cause analysis built as a Cause Map can capture all of the causes in a simple, intuitive format that fits on one page.  Once we’ve done that, we can identify all the solutions.

A worker is injured during a fall because the worker strikes the floor, or another object, and the object contacted is hard, and the worker hits in a way that causes injury.  When we say that workers are injured because they hit an object in a way that causes injury, what we are really talking about is factors that worsen a fall, and make injury more likely. The worker could land on a part of his or her body that is more easily injured.  Another way that injuries can be worsened is if a worker falls farther than his or her height (i.e., not a same-level fall).

The worker strikes the floor or other object because he or she falls, and there is no other support for the body, such as a handrail, or a harness.   There are four different ways to fall: slips, trips, the “step and fall” (where a person gets off-balance while stepping), and becoming unbalanced on moving equipment.

A worker slips when there is inadequate traction, either because the force of stepping off is too high, or the coefficient of friction is too low.  The force of stepping off can be higher than average if the worker is walking quickly or running, making a sudden change in direction, or if he or she has an awkward gait, from injury or old age, for example.  The coefficient of friction is a function of the traction provided by the shoes the worker is wearing and the “slipperiness” of the walking surface.  The coefficient of friction is too low if the traction of the worker’s shoes is inadequate and if the floor is slippery, because the surface is wet, icy and/or oily and does not have a non-skid coating.  Of course, for this to be an issue at all, the worker has to step into the slippery area.

A worker can become off-balance by encountering an unexpected height difference (known as the “step and fall”).  This occurs in one of two ways.  Either the front foot lands on a surface lower than expected, or the ankle turns due to one side of the foot ending up higher than the other side, with footwear that inadequately supports the ankle.  These are both due to an unexpected height difference.

When a worker trips, it is because his or her toe is stopped, but his or her upper body is not stopped.  The upper body is moving because the worker is moving and he toe is topped because it encounters an object in the walking path, a rise in the walking path, or a difference in height of subsequent stairs.

Last but not least, falls can be caused by workers who become unbalanced on moving equipment.  For this to occur, the worker must be inadequately secured to the equipment while the equipment changes motion, either by turning, decelerating or stopping, or accelerating or starting to move.

Once we have built our Cause Map and found all the potential causes, we can assign potential solutions to all appropriate causes.  The solutions are in green boxes, near the cause(s) they “solve”.   You can see that some of the solutions are the responsibility of the company, and some are the responsibility of the worker, and some are both.   Although many of the responsibilities lie with the worker, it is in a company’s best interest to provide training on how to prevent, manage and mitigate falls.  Falls may seem like everyday, ordinary minor occurrences, but the consequences can be anything but minor.

Root Cause Analysis - Incident Investigation

Planes Nearly Collide Over DC

By ThinkReliability Staff

Two planes came within seconds of a collision on  July 31, 2012 when both were directed to the same airspace by controllers.  Although no incident occurred, such near misses should be investigated thoroughly to prevent incidents in the future.

We can perform a root cause analysis of this incident in visual Cause Mapping form.  We begin with the impacts to the goals.  In the case of a near-miss like this one, some of the impacts to the goals will be hypothetical, based on the potential of the incident actually occurring.  For example, the safety goal is impacted because of the potential of death or injury to the passengers and crew on the planes.  The property goal is also impacted due to the potential of damage to the planes.  Even though this incident was considered a near-miss, there were some actual impacts to the goals, such as the delay in landing of the inbound plane, which can be considered an impact to the customer service, schedule, and  labor goal.

Once we have determined the impacts to the goals, we can begin the analysis by asking “why” questions.  In this case, the safety and property goals were impacted due to the potential collision of two planes.  These planes could have collided because they were on a collision course.   One plane was taking off directly towards another  plane that was trying to land.  The landing plane was landing in the opposite direction as usual (from the South instead of from the North) in order to avoid high winds from an incoming storm.  The plane taking off was cleared to take off towards the incoming plane (towards the South) by a different controller who was unaware that incoming planes were coming in from a different direction.  Communication of the change in incoming flights was not made to all controllers in the area and, although no details are available, it appears that the procedure used by the controllers when changing the flow towards the airport was inadequate.

There are thousands of recorded errors by air traffic controllers every year, and Reagan National (where this incident occurred) has had some particularly high-profile incidents, such as when a controller fell asleep (see   previous blog), involving air traffic controllers.  On August 10, 2012, two aircraft clipped each other at another Washington, DC area airport, although it is unclear if controllers were involved.  (See the article here.)  A congressional and FAA investigation is underway, and will hopefully address some needed improvements in air safety.

To view the Outline and Cause Map, please click “Download PDF” above.