ERRORS Module 2, Topic 1 Human factors

DISTRIBUTION OF ACCIDENTS REASONS HUMAN MISTAKES END ERRORS HUMAN FACTORS HAZARDOUS ENVIRONMENT PHENOMENA; MAINTENANCE & TRAINING & FINANCE ASPECTS ORGANIZATIONAL FACTORS EQUIPMENT MALFUNCTIONS TECHNICAL FACTORS ACCIDENT REASONS EQUIPMENT & FACILITIES AMBIENT HUMAN-OPERATOR 80% 15% 5% Human factors

HUMAN-ORIGINATED ACCIDENTS DISTRIBUTION Deficient psycho-emotional resistance at decision making and operations – 31% Violations and low level of crew co-ordination – 22% Lack of proficiency – 11% Interaction violations in “Air-Ground” communication channel – 10% Equipment ergonomics deficiencies (cockpit & ATCO workplace) – 9% Fatigue and poor heath state – 8% Lack of experience – 6% Shortcomings in line manuals and aviation legislation – 3% Human factors

INTENTIONAL NON-COMPLIANCE ERRORS The following is a refined discussion of human errors which is more operationally oriented: ERROR PROCEDURAL PROFICIENCY COMMUNICATION OPERATIONAL DECISION INTENTIONAL NON-COMPLIANCE Human factors

HUMAN ERROR Procedural error. An unintentional error that includes slips, lapses or mistakes in the execution of aviation regulations and/or company procedures. The intention is correct but the execution is flawed. These also include errors where the flight crew (air traffic controller) forgot to do something. Both written procedures and crew intention are required for procedural errors Communication error. An unintentional error that is a miscommunication, misinterpretation, or failure to communicate pertinent information within the flight crew or between the flight crew and an external agent (e.g. ATC or ground operations) Human factors

HUMAN ERROR Proficiency error. An unintentional error that indicates a lack of knowledge or physical skill Operational decision error. An unintentional, decision-making error, which is not specifically directed by aviation regulation or company operating procedures, that unnecessarily compromises safety (e.g. a crew’s decision to fly through known wind shear on an approach) Intentional non-compliance. A wilful deviation from aviation regulations and/or company procedures. If the crew is under heavy workload or commits the error only once, it would likely be a procedural error. However, if the crew makes the same error over and over again, or it is an error of complacency, then it is intentional non-compliance (i.e. a violation) Human factors

ERRORS AND ATC Fortunately, most of these errors are identified and corrected before an unsafe situation develops. Indeed, the frequency and severity of serious incidents and accidents involving air traffic services is remarkably low. The ATC system includes several built-in defences to protect against human or technical failures such as position reports, single direction routes, standard aircraft cruising altitudes and readback of instructions. Human factors

ERRORS AND ATC Analyses have shown that the most ATC errors occur in the following situations: under light to moderate traffic conditions and complexity during a controller’s first fifteen minutes on position when controllers have less than six years’ experience Human factors

CONTROL OF HUMAN ERROR To limit human error, one must first understand its nature. There are basic concepts associated with the nature of human error: the origins of errors can be fundamentally different and the consequences of similar errors can also be significantly different While some errors are due to carelessness, negligence or poor judgement, others may be induced by poorly designed equipment or may result from a normal reaction of a person to a particular situation. The latter kind of error is likely to be repeated and its occurrence can be anticipated Human factors

ERRORS AT THE MODEL INTERFACES Each of the interfaces in the SHEL model has a potential of error where there is a mismatch between its components. For example: The interface between Liveware and Hardware (human and machine) is a frequent source of error: knobs and levers which are poorly located or lack of proper coding create mismatches at this interface In the Liveware-Software interface, delays and errors may occur while seeking vital information from confusing, misleading or excessively cluttered documentation and charts Human factors

ERRORS AT THE MODEL INTERFACES Each of the interfaces in the SHEL model has a potential of error where there is a mismatch between its components. For example: Errors associated with the Liveware-Environment interface are caused by environmental factors (noise, heat, lighting and vibration) and by the disturbance of biological rhythms in long-range flying resulting from irregular working/sleeping patterns In the Liveware-Liveware interface, the focus is on the interaction between people because this process affects crew effectiveness. This interaction also includes leadership and command, and shortcomings at this interface reduce operational efficiency and cause misunderstandings and errors Human factors

CONTROLLING HUMAN ERROR The control of human error requires two different approaches APPROACHES I II minimize the occurrence of errors reduce the consequences of the remaining errors by cross-monitoring and crew co-operation Human factors

CONTROLLING HUMAN ERROR The control of human error requires two different approaches. First, it is necessary to minimize the occurrence of errors by: ensuring high levels of staff competence; designing controls so that they match human characteristics; providing proper checklists, procedures, manuals, maps, charts, SOPs, etc.; and reducing noise, vibration, temperature extremes and other stressful conditions. Training programmes aimed at increasing the co-operation and communication between crew members will reduce the number of errors (the total elimination of human error is an unrealistic goal, since errors are a normal part of human behaviour). Human factors

CONTROLLING HUMAN ERROR The control of human error requires two different approaches. The second avenue to the control of human error is to reduce the consequences of the remaining errors by cross-monitoring and crew co-operation. Equipment design which makes errors reversible and equipment which can monitor or supplant human performance also contribute to the limitation of errors or their consequences Human factors

STRATEGIES FOR ERROR PREVENTION Three strategies for error prevention, which is actually form of risk mitigation, are briefly discussed below. These strategies are relevant to flight operations, air traffic control or aircraft maintenance STRATEGIES ERROR REDUCTION ERROR CAPTURING ERROR TOLERANCE Human factors

ERROR REDUCTION ERROR REDUCTION STRATEGIES are intended to intervene directly at the source of the error itself, by reducing or eliminating the contributing factors to the error. They seek improved task reliability by eliminating any adverse conditions that increase the risk of error, and they are the most often-used strategies Examples of error reduction strategies include improving the access to a part for maintenance, improving the lighting in which the task is to be performed, and providing better training Human factors

ERROR CAPTURING ERROR CAPTURING assumes the error has already been made. The intent is to “capture” the error before the adverse consequences of the error are felt. Error capturing is different than error reduction in that it does not directly serve to reduce or eliminate the error Error-capturing strategies include post-task inspection, verification, or testing; for example, cross-checking a checklist. It should be noted that people may be less vigilant when they know there is an extra defence in place to capture their errors Human factors

ERROR TOLERANCE ERROR TOLERANCE refers to the ability of a system to accept an error without serious consequence. For example, as a strategy to prevent the loss of both engines on an aircraft involved in extended twinengine operations, the regulatory authority might prohibit the same maintenance task being performed on both engines prior to a flight Examples of measures to increase error tolerance are the incorporation of multiple hydraulic or electrical systems on the aircraft and a structural inspection programme that allows multiple opportunities to detect a fatigue crack before it reaches critical length Human factors

SUMMARY This item has briefly described the multifaceted and pervasive nature of Human Factors issues in aviation safety. To assist in understanding the complex interactions of Human Factors, the SHEL model was discussed The SHEL model provides a systematic framework for the safety auditor for checking for the presence of error-producing conditions and for the existence of violation-producing conditions within the aviation system. Since human errors are cited so frequently as being causal or contributory in aviation occurrences, different ways of considering human error were provided. Human error is a normal part of all human endeavour, therefore, eliminating it completely is an unrealistic goal Human factors

Questions and answers Human factors

QUESTIONS Describe operationally oriented errors at ATC? Human factors

QUESTIONS In what situations the most ATC errors are occurring? Human factors

QUESTIONS Describe strategies for errors prevention at ATC? Human factors

POINTS TO REMEMBER Distribution of accidents reasons Errors in ATC description Situations, when the most ATC errors occur Approaches for control of human error and error prevention References: Doc. 9859, Cir. 241 Human factors