Root cause: human error

How do you prevent a recurrence when someone screws up?

By Paul Studebaker

When something goes seriously wrong, it’s natural to want to prevent a recurrence. But what if the cause is human error -- an individual’s failure to do his job? There are so many ways people make mistakes, it may not be practical (or possible) to idiot-proof the system. Then what do you do?

This sort of question has come up loudly and frequently in the wake of Hurricane Katrina, where blame for the level of devastation has been laid on everyone from French settlers and levee engineers to every stratum of government, and even the victims themselves.

It’s difficult to wrap your arms around Katrina, but dealing with human error is nothing new to engineers and managers. Many say they see a steadily increasing need to deal with such mistakes as experienced workers retire and are replaced by the current crop of inadequately prepared and poorly motivated new recruits.

Some pundits claim the only way people learn is by making mistakes. Many experts prescribe training or retraining, certification and recertification. The general population calls for error-proof systems using redundant personnel or technology.

Here are some recent examples where it appears that human error led to significant consequences and, in some cases, loss of life. We’re seriously interested in how you would handle these or similar situations that might arise in plants like yours. What would you do?

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On March 23, 15 workers were killed and more than 170 injured at BP’s Texas City, Texas, refinery when an isomerization unit exploded. Investigators concluded that BP unit managers and operators overfilled and then overheated the raffinate splitter. The resulting sudden increase in pressure forced a large volume of hydrocarbon liquid and vapor into the adjacent blowdown stack, quickly exceeding its capacity. An unknown source ignited the resulting vapor cloud.

If unit managers had properly supervised the startup or if operators had followed procedures or taken corrective action earlier, the explosion would not have occurred, the report says.

The number of deaths and injuries increased because workers were in temporary trailers near the blowdown stack, and the company failed to evacuate people when it became apparent pressure was building in the unit and vapors were venting. The investigation team also concluded the use of a flare system, instead of a blowdown stack, would have reduced the severity of the incident.

BP will take disciplinary action against supervisory and hourly employees directly responsible for operation of the unit, ranging from warnings to termination. What would you do?

On September 12, half of Los Angeles and surrounding communities were blacked out for more than an hour when power company technicians installing a monitoring system at a transmitting station cut the wrong bundle of wires.

Though there was no sign of sabotage, authorities declared a state of emergency and police went on full tactical alert. Gasoline prices jumped more than 7 cents per gallon in the city after three refineries went offline, and local hospitals canceled procedures scheduled for the afternoon. The Los Angeles County Economic Development Corp. estimated the cost of the outage, in terms of lost productivity, at $23 million per hour.

The incident was first blamed on the electricians who cut the wires, but ultimately traced to an inaccurate work order. As we go to press, no corrective action has been announced. What would you do?

On September 17, two people were killed and about 80 injured when a Chicago Metra commuter train derailed. The train was attempting to negotiate a 10 mph set of switches at 69 mph. The engineer says the signal was green, indicating the switches were clear and the train should proceed at full speed.
Investigators examined the tracks and signaling equipment and found everything in working order. It would cost about $1.6 billion to equip the rail system with sensors and controls that would stop a train if an engineer passes a signal without responding. What would you do?
Please let us know by e-mailing me at the address below.

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