Two Countries Apply Trusted Human Factors Model to Manage Safety

April 23, 2015
CASA has adopted PEAR as an essential part of its ongoing program, Safety Behaviours: Human Factors for Engineers, for training maintenance human factors

Today’s maintenance personnel have a reasonable understanding of the human factors challenges in their life and work environment. They hardly need a basic course. Instead, they require ways to identify and report human factors and other hazards before they become serious threats to worker and flight safety. Bill Johnson (FAA) and Gareth McGraw (Civil Aviation Safety Authority of Australia, (CASA)) combine to review the focus on People, Environment, Action, and Resources (PEAR). Because of its simplicity, this time tested method of understanding maintenance human factors (HF) continues to evolve for worldwide application.

PEAR History

SHEL/SHELL was the primary HF learning tool for most pilot crew resource management courses in the eighties and early nineties. The later tools took focused mostly on human error. That includes James Reason’s Swiss Cheese Model and Gordon Dupont’s Dirty Dozen. Boeing’s Maintenance Error Decision Aide (MEDA) certainly deserves a predominate spot in the list of materials that affected HF education and implementation.

While reduction and mitigation of human error was an important focus of HF familiarization, Drs. Mike Maddox and Bill Johnson wanted something that extended beyond error. Their specification was for a tool, or memory jogger, that could encompass all aspects of maintenance work. Their solution, while often called a model, was really a pneumonic that captured a way to consider maintenance human factors. Maddox and Johnson knew that HF programs must consider people, the environment in which they work (physical and social), the actions that must be performed, and the resources necessary to complete the job in a safe and efficient manner. Those four elements created PEAR.

PEAR Described

The PEAR concept is simple (see Figure 1). There are only four words to remember. That is a pleasant relief to mechanics/engineers who are learning about and applying maintenance HF. They remember the four letter words, like PEAR. Of course, there are many relevant concepts associated with each letter. Figure 2 shows an early example of items that are associated with people.

Another version of People is offered by the Civil Aviation Safety Authority of Australia (CASA). The nice thing about PEAR is that it has expanded, adapted, and usually improved by many who have applied it.

Swiss Cheese, Dirty Dozen, and other training approaches had the usual set of materials and media. PEAR is best described in the FAA’s Maintenance Human Factors Presentation System that is on the FAA website, referenced at the end of this article. 

Systems like PEAR are only as good as their usability and versatility in the maintenance environment. The remainder of this article shows excellent examples from Australia.

The Evolution and Application of PEAR in Australia

“Come and go” aviation safety initiatives can be likened to nature’s selection process. The most adaptive species prosper as they are the ones that find solutions to their environment’s constantly changing hazards and challenges. Those that can’t adapt quickly become extinct. With regard to aviation safety, any idea that doesn’t prove to be easily understandable and useful in providing practical safety solutions will also likely quickly become extinct!

PEAR is evolving to be one of safety’s ‘adaptive species’. It is an intuitive model that is easy to understand at all levels of the organization. The PEAR approach provides the ability to be applied across a wide array of contexts, processes, and environments. PEAR can structure and collect reactive, pro-active, and predictive data/information to meet the needs of today’s safety management systems.  One example of adaptation is how the “A” in PEAR has been used to look for human factors threats in job and task analysis.

CASA has adopted PEAR as an essential part of its ongoing program, Safety Behaviours: Human Factors for Engineers, for training maintenance human factors (See AMT September 2013). In an effort to ensure that training information is used, CASA developed PEAR-centric aids for working planning, event investigation, and other hazard reporting. 

The various planning and reporting aids show the strength and versatility of PEAR. It does not force engineers into an additional time consuming process. Instead, it is part of the way they normally identify and adapt to known and emerging hazards. It is easy for the workforce to see hazards in the people, environment, actions, and resources categories. Let’s look at two CASA examples that apply PEAR.

Many investigators, including the author, have observed that many events are the result of poor planning. One solution is to structure [planning] behaviour to identify those human factors categories identified in PEAR. Engineers can then apply a simple risk assessment tool called the “Rule of Three (ROT).” The idea is that there are three ‘categories' of circumstances or conditions that can be present in any job or task. The conditions can be assessed by the engineers/mechanics. The Rule of Three is shown in Figure 5.

The ROT assessment helps the worker to identify a single hazard or a combination of hazards that call for proceeding as usual,  proceeding with interventions, or stopping a task altogether. This system is similar to Threat and Error Management. The combination of straightforward concepts, like PEAR and ROT, make safety management a field application. Figure 6 shows a PEAR-based pre-task planning flowchart to which engineers can apply the Rule of Three.

Figure 5: The Rule of Three

GREEN: Condition is OK and well within limits or assumptions

AMBER: While within limits the condition or circumstance is close to the edge of being acceptable

RED: Condition or circumstance is definitely out of limits

For that appropriate action, the ROT follows this process

All GREEN = OK to proceed using normal controls

RED = STOP, action must be taken to mitigate a red back into a green (or possibly AMBER)

One or two AMBERS = Proceed with increased caution as some controls may well be weakened

Three AMBERS = RED and STOP! Controls may be significantly weakened; action must be taken to reduce one or more AMBER into the GREEN

The CASA Safety Behaviours: Human Factors for Engineers Safety Behaviours: Human Factors for Engineers training will have its greatest impact if the training language is reinforced with job aids/tools. One enterprising CASA Airworthiness Inspector provided this type of tool when he adapted a well-known investigation template to use PEAR as its framework for identifying contributing factors to a maintenance event or incident. 

Now, engineers are using PEAR to shape their approach to pro-active HF hazard identification. Organizations are applying the PEAR categories as a common language to aid engineers in isolating previously unidentified HF contributing factors after an incident or event has occurred. This information can then be used in adapting existing maintenance practices, processes, behaviors or controls to make them work better. It is flight line and shop level safety management.

In conclusion, the simple elegance of PEAR is that it doesn’t rigidly drive specific actions. It allows individuals and organizations to more effectively identify and design their own improvements and adaptations to the changing environmental and organizational hazards often found in aviation maintenance. CASA intends to insure that PEAR will evolve and survive as one of safety’s natural selections.

For additional information about PEAR and other maintenance Human Factors tools see the CASA (http://www.casa.gov.au/scripts/nc.dll?WCMS:STANDARD::pc=PC_100994) and FAA (www.humanfactorsinfo.com) websites. Another version of this article appeared in An FAA HF Newsletter in March 2015.

Dr. William Johnson is the FAA Chief Scientific and Technical Advisor for Human Factors in Aircraft Maintenance Systems. He is the top FAA executive responsible for R&D and technical programs related to human performance in maintenance/engineering. He is an aviation maintenance technician and a pilot for nearly 50 years. He is a regular AMT contributor. 

Gareth McGraw is a Human Factors Advisor with Australia’s Civil Aviation Safety Authority. He is an aviation maintenance technician with 27 years’ experience in both civil and military aviation, including two and a half years as a qualified air safety investigator.