Human error: Fault analysis approach

While investigating a failure, blaming individual is more satisfying than targeting institution. Human errors are not rare and error factors are always surrounding us. Everyone can make error even if one is highly trained, experienced and motivated. There is no single report to cover all industry data to identify human errors; however numerous accident and incident analysis shows that 90-95% of accidents are due to human error, likewise 95% of all road accidents are due to human error. The costs of such human failure can be minor or could result in even loss of life or lives.

Below are some well-known human error which caused loss of millions and loss of invaluable lives.

  1. January 2012 – Costa Concordia – Cruise ship ran aground due to navigational error, killing 32 people and approx. cost to owner was $2bn (Reuters , 6th July 2014).
  2. 1st October 2015 – S.S. Al Faro sank in the Atlantic Ocean, master’s failure to avoid hurricane. All 33 lives on-board were lost.
  3. July 1988 – Piper Alpha oil rig disaster – A lack of communication between shift changes caused leak of gas and explosion. Loss of more that £1bn and 167 lives.
  4. April 1986 – Chernobyl Disaster – The safety systems had been switched off, a cascade effect of basic engineering deficiencies in the reactor and faulty actions of the operators caused this disaster.
  5. January 1986 – Shuttle Challenger explosion – Reason was an O-ring seal , which didn’t launch.
  6. March 1979 – Three Mile Island in Pennsylvania – Partial Meltdown of Nuclear power plant.
  7. April 1947 – SS Grand camp at Texas City port. There was no safety precaution in place to handle Ammonium Nitrate loading, it caused biggest non-nuclear explosion on-board SS Grand champ, killing 100s including staff of fire fighting team.

Largely human errors are always understood as operators fault, but in industry, there are 2 approaches of human unreliability; first is the person approach and second is the system approach.

Person approach

It mainly focuses on unsafe act or violation by individual which may arise primarily from abnormal mental processes such as forgetfulness, inattention, poor motivation, carelessness, negligence and recklessness. Obviously, the associated countermeasures against failure are directed mainly at reducing unwanted variability in human behaviour, which can be set by procedures and disciplines.

System approach

The system approach is based on the belief that actions of human are not always perfect and errors are expected. It concentrates on the conditions under which individuals work and tries to build defences to prevent errors or reduce their effects. In any organization, even with highly trained people and defensive system, regular error traps gives rise to the consequential errors. The system approach is to identify how the defence failed.  And the approach is to counteract it by changing the conditions under which human work.

How to identify human errors?

The Swiss cheese model of accident causation was developed by Professor James T. Reason and is widely used in engineering, aviation and other industries to explain the cumulative effect of defence layer breakdown and is very useful tool of risk management. Here the layers of cheese represent layers of defence against any failure. The slice of cheese has holes due to active failures and some are latent conditions. Active failures are unsafe acts directly related to failure, like operator mistake; whereas latent conditions remain hidden for days or weeks or months till accident or failure occur.

There are always barriers, safeguards and defence systems around any hazard; any failure should not be analysed by who did it, but analysis should be done for how the defence system failed and how was the safety barrier crossed. Analysis should include the error in procedure, component design, and material or complexity of system or operator’s action.

Systematic new methods for It also suggests ways in which current methods of protection may be enhanced, and concludes by discussing the unusual structural features of High reliability organizations. It also suggests ways in which current method of protection may be enhanced, and concludes by discussing the usual structural features of high reliability. Risk assessment and risk management are required to develop a high reliability organization, find and suggest new ways to improve protection against errors and develop reliability. The process of improving protection is to add extra layer of cheese i.e. insert defence system to make the organization or act more unfailing.


Normal condition when there is no fault, Latent conditions of failure are there but HAZARDS are not passing through the defence.


Hazards are passing through all defences when error in all defence systems are aligned.

How to analyse the case of failure on Ship?

There are primarily 3 categories of factors which result into failure; skill-based errors, decision errors and violation. Ships are like a moving industry where human, nature, internal and external factors are always prevailing. There are always multiple layers of defence system against failure, as we have seen in Swiss cheese model, one error will not cause failure, but failure of multiple defence in combination will cause failure.

If a navigational watch keeper is not attentive on watch, a Bridge Navigation watch Alarm system is another layer of defence. If main engine lubrication fails due to dirty filter, there is low pressure alarm as first layer of defence, slow down as 2nd layer of defence and trip 3rd layer of defence.

So, when analysing any failure, one should analyse all layers of defence involved in failure and investigate the latent conditions, not just pinpoint at the active failure, i.e. the frontline worker. Below factors in combination could be the causation of failure;

A Navigational failure –

Factors of error –Slide5

  1. Skill of watch keeper
  2. Condition and reliability of navigational equipment
  3. Latent condition of equipment
  4. Other vessel (if involved)
  5. Weather condition
  6. Fatigue and stress
  7. Communication
  8. Mental status of watch keeper
  9. Decision making
  10. Risk awareness
  11. Wrong procedure
  12. Violation

A Machinery failure –Slide4

Factors of error –

  1. Skill of watch keeper
  2. Condition and reliability of equipment
  3. Latent condition of machinery
  4. Fatigue and stress
  5. Communication
  6. Use of appropriate tool
  7. Workplace condition
  8. Decision making
  9. Risk awareness
  10. Wrong procedure
  11. Violation

What to look  for when analysing fault and what corrective action should be implemented as defence?

In order to avoid accidents and failures, organization needs to utilise technical and engineering measures robustly to manage human failures. Organisation must manage and implement best procedures, component design, component material, simplifying the complexity of system and training to operators to make defence against errors. When analysing fault one must check is it an organisational error? Is it a component error? Is it an interface error? Or, is it an operator’s error? Following are the points under each category to look for;

Organisational error

All the organisations has a set procedure about any operation or maintenance, it can be related to vessel navigation, operation or maintenance. Another point is resource management.

Defence – Right selection of human resource for right task, Redesign the procedure, Accurate procedure, Human engineered and enforceable procedure warning, training, clean and understandable, Good communication procedure.

Component error

Component design, selection of component material, Selection of equipment, malfunction of equipment.

Defence –Redesign of component, select new component, replace old component with new more reliable one.

Interface error

Complexity of system, use of component, navigational equipment, maintenance equipment, other equipment, tools etc.

Defence – Control and display design, use of automation, easily accessibility, simple to use, training parted to user.

Operator’s error

Poor maintenance, no maintenance, wrong operation, poor skill,  poor knowledge, Physical condition ( like fatigue), poor lighting, poor operating conditions.

Defence – Training to operator, selection of skilled labour, rest hours to operators, sufficient lighting, and safety at work place.

How to reduce human error?

Human errors cannot be prevented entirely, but can be reduced. Every failure gives an opportunity to assess the risk all over again, find and implement new safety layer. It can be done at every stage from organization to operator. Below are the key

  1. Organizational level – Documentation control, risk management, accurate procedure to be set keeping in mind about human factors
  2. Component level – Redesign jobs, components and procedure, consider the human capabilities, work place designed, lay out etc.
  3. Interface level – Training about why, what and how, Good communication set up
  4. Operator’s level – Pre job training and supervision for critical tasks, and regular tasks too.
  5. Evaluate performance of individual

RISK ASSESSMENT is the best tool to prevent and avoid human errors.


Categories: Crew matters, Eng & Tech, Industry, Navigation, Safety, Service experience

Tags: , , , , ,

2 replies

  1. Good article on accident causation. To get to the root cause of any accident- one useful method is to ask ‘why’ five times.

    Swiss cheese is a great model but at the same time I have created a simpler model of safety systems and safety culture for seafarers called the ‘Safe-Man’ model. I’ve described this in detail in my book Golden Stripes- Leadership on the High Seas.



  1. Care in ship’s daily operation – MarinerOnBoard

Thanks for your feedback.

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: