human factors

Description

The Dirty Dozen refers to twelve of the most common human error preconditions, or conditions that can act as precursors, to accidents or incidents. These twelve elements influence people to make mistakes. The Dirty Dozen is a concept developed by Gordon Dupont, in 1993, whilst he was working for Transport Canada, and formed part of an elementary training programme for Human Performance in Maintenance. It has since become a cornerstone of Human Factors in Maintenance training courses worldwide, as exemplified in UK CAA CAP715[1].

The Dirty Dozen is not a comprehensive list of human error accident precursors, for example, ICAO Circular 240-AN/144[2] lists over 300 human error precursors. However, since 1993 all areas of the aviation industry, not just aircraft maintenance, have found the Dirty Dozen a useful introduction to open discussions into human error in their businesses, organisations and workplaces. So, it may be possible to find Dirty Dozen lists for pilots, ramp workers, air traffic controllers and cabin crew.

The Dirty Dozen is also used to refer to a poster campaign, developed by the Maintenance And Ramp Safety Society (MARSS) in support of the original Transport Canada training programme. Each poster illustrates a different human factor.

Countermeasures

Whilst The Dirty Dozen list of human factors has increased awareness of how humans can contribute towards accidents and incidents, the aim of the concept was to focus attention and resources towards reducing and capturing human error. Therefore, for each element on The Dirty Dozen list there are examples of typical countermeasures designed to reduce the possibility of any human error from causing a problem.

1. Lack of communication
2. Distraction
3. Lack of resources
4. Stress
5. Complacency
6. Lack of teamwork
7. Pressure
8. Lack of awareness
9. Lack of knowledge
10. Fatigue
11. Lack of assertiveness
12. Norms

Poor communication often appears at the top of contributing and causal factors in accident reports, and is therefore one of the most critical human factor elements. Communication refers to the transmitter and the receiver, as well as the method of transmission. Transmitted instructions may be unclear or inaccessible. The receiver may make assumptions about the meaning of these instructions, and the transmitter may assume that the message has been received and understood. With verbal communication it is common that only 30% of a message is received and understood.

Detailed information must be passed before, during and after any task, and especially across the handover of shifts. Therefore, when messages are complex they should be written down, and organisations should encourage full use of logbooks, worksheets, and checklists etc. Verbal messages can be kept short, with the most critical elements emphasised at the beginning and repeated at the end. Assumptions should be avoided and opportunities for asking questions both given and taken.

Complacency can be described as a feeling of self-satisfaction accompanied by a loss of awareness of potential dangers. Such a feeling often arises when conducting routine activities that have become habitual and which may be “considered”, by an individual (sometimes by the whole organisation), as easy and safe. A general relaxation of vigilance results and important signals will be missed, with the individual only seeing what he, or she, expects to see. Complacency can also occur following a highly intense activity such as recovering from a possible disaster; the relief felt at the time can result in physical relaxation and reduced mental vigilance and awareness. This particular psychological experience is referred to as a Lacuna.

Whilst too much pressure and demand causes over-stress and reduced human performance, too little results in under-stress, boredom, complacency and reduced human performance. It is therefore important, when conducting simple, routine and habitual tasks, and when fatigued, to maintain an adequate, or optimum, level of stress through different stimulation. Always expect to find a fault! Following written instructions, and adhering to procedures that increase vigilance, such as inspection routines, can provide suitable stimulus. It is important to avoid: working from memory; assuming that something is ok when you haven’t checked it; and, signing off work that you are unsure has been completed. Teamwork and mutual cross-checking will provide adequate stimulus when fatigued.

The regulatory requirements for training and qualification can be comprehensive, and organisations are forced to strictly enforce these requirements. However, lack of on-the-job experience and specific knowledge can lead workers into misjudging situations and making unsafe decisions. Aircraft systems are so complex and integrated that it is nearly impossible to perform many tasks without substantial technical training, current relevant experience and adequate reference documents. Furthermore, systems and procedures can change substantially and employees’ knowledge can quickly become out-of-date.

It is important for employees to undertake continuing professional development and for the most experienced workers to share their knowledge with colleagues. Part of this learning process should include the latest knowledge on human error and performance. It should not be a taken as a sign of weakness to ask someone for help or for information; in fact this should be encouraged. Checklists and publications should always be referred to and followed, and never make assumptions or work from memory

Distraction could be anything that draws a person’s attention away from the task on which they are employed. Some distractions in the workplace are unavoidable, such as loud noises, requests for assistance or advice, and day-to-day safety problems that require immediate solving. Other distractions can be avoided, or delayed until more appropriate times, such as messages from home, management decisions concerning non-immediate work (e.g. shift patterns, leave entitlement, meeting dates, administrative tasks etc), and social conversations.

Psychologists say that distraction is the number one cause of forgetting things: hence the need to avoid becoming distracted and to avoid distracting others. Humans tend to think ahead. Thus, when returning to a task, following a distraction, we have a tendency to think we are further ahead than we actually are.

To reduce errors from distraction it is best to complete a task before responding. If the task cannot be completed without hurrying, then we can prominently mark (or, “lock off”) the incomplete work as a reminder to ourselves and anyone else who may complete the work. When returning to work, after being distracted, it is a good idea to commence at least three steps back, so that we re-trace some steps before picking up the task again. If necessary, having someone else double-check our work using a checklist may be appropriate and useful.

Management have a role to play in reducing the distractions placed on their employees. This may involve good workspace design, management of the environment, and procedures that create “safety zones”, “circles of safety” or “do not disturb areas” around workers engaged in critical tasks.

In aviation many tasks and operations are team affairs; no single person (or organisation) can be responsible for the safe outcomes of all tasks. However, if someone is not contributing to the team effort, this can lead to unsafe outcomes. This means that workers must rely on colleagues and other outside agencies, as well as give others their support. Teamwork consists of many skills that each team member will need to prove their competence.

Some of the key teamwork skills include: leadership, followership, effective communication, trust building, motivation of self and others, and praise giving.

To create an effective team it is necessary that the following issues, as appropriate, are discussed, clarified, agreed, and understood by all team members:

• A clearly defined and maintained aim, or goal(s)
• Each team member’s roles and responsibilities
• Communication messages and methods
• Limitations and boundaries
• Emergency procedures
• Individual expectations and concerns
• What defines a successful outcome
• Debriefing arrangements
• Team dismissal arrangements
• Opportunities for questions and clarification

A team’s effectiveness can also be improved through the selection of team members to reflect a broad range of experience and skill sets, and also through practice and rehearsal.