Human Factors in Aviation Safety FLT241

Learning Outcomes

  • Significance of human error in major aircraft accidents.
  • Factors that affect human performance.
  • Definition of human error and HFACS explanation method used to classify human error.
  • Explanation of Management of Human Error.
  • Concepts behind CRM, LOSA, TEM in modern commercial aviation.

What is Human Factors?

Definition # 1: Human Factors (or ergonomics) is the scientific discipline concerned with the understanding of interactions among humans and other elements of a system, and the profession that applies theory, principles, data and methods to design in order to optimize human well-being and overall system performance.

Definition #2: Human Factors is about people: it is about people in their working and living environments, and it is about their relationship with equipment, procedures, and the environment. Just as importantly, it is about their relationships with other people.... Its two objectives can be seen as safety and efficiency.

Why do Smart People do Dangerous or Dumb Things?

Excessive Workload

  • Physical and cognitive effort involved in task performance.

Lack of Situational Awareness

  • What's going on?
  • What's likely to happen next?
  • What will happen if I take a particular action?

Excessive Stress, Fatigue, Uncertainty, etc...

  • Impacts perceptual- motor performance, decision making, etc...

Diminished Attention

  • Too much to attend to at once (overload)
  • Too little to attend to for too long (underload)

Poor Teamwork and Communication

  • Often due to poor layout of work space and/ or poor layout command and communication structure.

Avoiding Errors by Using ADM

The FAA describes the Aeronautical Decision Making (ADM)model as a systematic approach to the mental process used by aircraft pilots to consistently determine the best course of action in response to a given set of circumstances.

When in Doubt Always...

The Human Factors Analysis and Classification System (HFACS)

HFACS is a theoretically based tool for investigating, analyzing, and classifying human error associated with aviation accidents and incidents.

Reason's Swiss Cheese Model

Features of the Swiss Cheese Model

  • Systems are protected by multiple layers of defenses that are designed to prevent hazards or system failures from cascading into accidents.
  • Each layer of protection, however can develop "holes" or flaws through safety deficiencies, resembling swiss cheese.
  • When the holes in each of the layers of defenses line up, an accident occurs.

Real World Problems Using Reason's Swiss Cheese Model

Organizational Influences

  • Rapid Expansion
  • Lack of Regulation
  • Management "lip service" to safety

Unsafe Supervision

  • Risks and hazards neglected
  • Poor work scheduling- fatigue
  • Insufficient training

Preconditions for Unsafe Acts

  • High workload
  • Time pressure to perform tasks
  • Ignorance of the system

Unsafe Acts

  • Aircraft warning system disabled
  • Ommission of critical checklist item
  • Over- reliance on automation

Real Life Accident Using the Swiss Cheese Model

Comair Flight 5191

Attempted takeoff from the wrong runway, On August 27, 2006. This report explains the accident involving a bombardier regional commuter jet which crashed during takeoff. The flightcrew was instructed by ATC to take off from the long runway 22, but instead took off on the short runway 26, ran off the end of that runway and crashed, killing 49 people. The NTSB determined the probable cause as follows:

The National Transportation Safety Board determines that the probable cause of this accident was the flight crewmembers’ failure to use available cues and aids to identify the airplane’s location on the airport surface during taxi and their failure to cross-check and verify that the airplane was on the correct runway before takeoff. Contributing to the accident were the flight crew’s non pertinent conversation during taxi, which resulted in a loss of positional awareness, and the Federal Aviation Administration’s failure to require that all runway crossings be authorized only by specific air traffic control clearances.

Crew Resource Management

Is a set of training procedures for use in environments where human error can have devastating effects. Used primarily for improving air safety, CRM focuses on interpersonal communication, leadership, and decision making in the cockpit. Modern CRM theory accepts that human errors are indeed inevitable; therefore CRM practices should serve as a set of counter measure with three distinct lines of defense:

  • First- Error avoidance if possible.
  • Second- Trapping incipient errors before they are committed.
  • Finally- Mitigating the consequences of those human errors which occure and are not trapped.

Line Operations Safety Audit (LOSA)

The LOSA process uses an airline observer (usually a pilot) to collect data about flight crew behavior by riding on the "jump seat" during routine flights and observing crew strategy for managing threats, errors and undesirable aircraft states.

Threat and Error Management (TEM)

Focuses on the normal working environment and the humans working in that environment.

  • Threats- Pilots must manage threats that come at them in the normal operating environment.
  • Errors- Human error comes from the crew and may be innocent or intentional.
  • Undesired Aircraft State- an error not well managed which may lead to an event which compromises safety. An undesired aircraft state (UAS) is defined as a position, speed, altitude, or configuration of an aircraft.

Strategies to Manage Threats and Errors

  • Installment of Hard defense Mechanisms- GPWS
  • Installment of Soft Defense Mechanisms- Checklist, rules and regulations, standard operating procedures etc....
  • Cockpit Standardization
  • Cockpit Automation and Precision Navigation
  • Identification of Communication Issues
  • Identification of Professionalism in Aviation
  • Sterile Cockpit Rule (FAR 121.542)

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