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Human Factors

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Human Performance

by Kent B. Lewis

Human Performance in aviation is the study of pilot, crew, mechanic and controller performance and health issues. Performance in any system is affected by human factor issues such as design of flight decks, physiological and psychological variations, and the interaction and communication between all participants.

Human Factors

“A broad field that studies the interaction between people and machines for the purpose of improving performance and reducing errors. As aircraft become more reliable and less prone to mechanical failure, the percentage of accidents related to human factors increased. Some aspect of human factors now accounts for over 80 percent of all accidents. Pilots who have a good understanding of human factors are better equipped to plan and execute a safe and uneventful flight.” (FAA Instrument Flying Handbook, 2001, p. 1-1)

Within human factors, specializations develop that use an interdisciplinary approach to the scientific study of the complex human-machine system. Examples of these specializations are aeromedical, critical incident response, first responder stress debrief, professional standards and pilot assistance.

  • Human factor elements include:
  • Design/System Failure
  • Organizational
  • Supervisory
  • Medical/Physiological/Psychological
  • Communications
  • Crew Resource Management
  • Aeronautical Decision Making
  • Attitude/Personality
  • Knowledge or Skill
  • Sensory-Perceptual

Mishaps: “WHO” did “WHAT?”

“The Naval Safety Center periodically publishes a list of the most common aircrew errors, shown below:

  • Inadequate crew coordination
  • Procedural violation
  • Physical or mental condition
  • Misuse of flight controls
  • Inadequate flying speed
  • Poor flight preparation
  • Inadequate lookout procedure

While the above designations are good descriptors concerning human error mishaps, they do not tell us much about the “Whys”. From a human factors standpoint, we need to relate the occurrence of mishaps to the behavior of people in the performance of their jobs. Accomplishing this may may be possible if we can more accurately define human factor “causes” of accidents, and through an understanding of the capabilities and limitations of human performance, develop improved mishap prevention measures.” (Naval Postgraduate School Aviation Psychology Lecture Summaries, 1992, p.3)

These same type of errors may result in injury to factory workers, poor performance of surgical teams or inefficient business management. Development of intervention strategies to combat poor performance and optimize system capabilities are key to everyone’s bottom line. To do this, we must identify “Why” and target the most appropriate levels for intervention.

DoD and the FAA are currently collaborating on defining human factor causes with the development of a Human Factors Analysis and Classification System (HFACS). Traditional intervention strategies focus on prevention of specific types of accidents, such as Controlled Flight Into Terrain (CFIT) or Stall/Spin mishaps rather than human error. Corrective recommendations have been focused on decision-making vs a wide range of possible human error categories. Causal factors must be analyzed and classified to accurately capture and recreate the complex layers of human error in context with the individual, environment and mishap or event. The resulting taxonomy will address latent failures of the system and active failures of the operator, from the earliest opportunity for intervention to the last.

The DoD HFACS model currently addresses these basic layers of system failure:

Organizational influences

  • Resource/Acquisition management
  • Organizational climate
  • Organizational process


  • Inadequate supervision
  • Planned inappropriate operations
  • Failure to correct known problem
  • Supervisory violations

Preconditions to Acts

  • Environmental factors
  • Physical
  • Technological
  • Condition of individuals
  • Cognitive factors
  • Psycho-behavioral factors
  • Adverse physiological states
  • Physical/mental limitations
  • Perceptual factors
  • Personnel factors
  • Coordination/communication/planning factors
  • Self-imposed stress


  • Errors
  • Skill-based
  • Judgement and Decision -making errors
  • Misperception errors
  • Violations

A Human Factors Intervention Matrix (HFIX) is being developed to pit Unsafe Acts against Intervention approaches, as a useful tool to evaluate safety programs. As part of the FAA’s Safer Skies initiative, Joint Safety Analysis Teams and Joint Safety Intervention Teams studied civil aviation accidents associated with:

    -Controlled Flight Into Terrain (CFIT)
    -Approach and Landing
    -Loss of Control
    -Runway Incursions
    -Pilot decision-making

The results were classified based on NTSB recommendations for corrective action. The results found that that NTSB recommendations routinely targeted Organizational/Administrative levels (36%) and Technological/engineering approaches. “However, unlike the NTSB where relatively few recommendations targeted the human, nearly 1/3 of those obtained from JSAT/JSATs did so.” (Developing a Methodology for Assessing Safety Programs Targeting Human Error in Aviation, 2004, p. 4) Analysis suggests that additional interventions should be directed towards skill based errors, violations and modification of the task and environment.

In the majority of cases, a mishap “happens” before the aircraft has ever left the ground, at times as high as the organizational or supervisory level. Mishaps are caused by hazards with human and material factor roots. Identification of hazards through the use of system based safety programs and risk management methodologies will result in interventions at the earliest and most appropriate levels. The earlier that a hazard is identified, the earlier it can be assessed, eliminated or controlled.

Safety Quote
“You can’t go on liberty if you’re dead”.
Lt Col Michael Kurth, HMLA-369
Navy Cross recipient
Desert Storm

Preflight yourself before you go….Know your personal limitations. Use the PAVE checklist.

Another NASA, DoD and FAA initiative is the National Plan for Civil Aviation Human Factors

Two goals:
1. Reducing error in human-system interactions
2. Increase efficiency of human-system performance

The national agenda focuses on 2 major elements
1. Human-centered automation
2. Selection and training
3. Human performance assessment
4. Information management and display
5. Bioaeronautics

-Application of research:
1. Create environment for change
2. Develop HF education and training programs at all levels
3. Equip personnel and facilities with modern tools and techniques of the HF engineering discipline.
4. Develop infrastructure to translate and disseminate human factors products.

Contact info:

Written by Clark

March 11, 2007 at 4:44 pm

Posted in Uncategorized

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