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Last updated: April 10, 2019

center510005452745Advanced Human Factors in AviationBubba DayAVN3101 4/19/18906000Advanced Human Factors in AviationBubba DayAVN3101 4/19/18TABLE OF CONTENTSPAGEExecutive Summary21. Introduction31.131.2 31.3 The Dirty Dozen32.

Scenarios42.1 Scenario 142.2 Scenario 262.3 Scenario 372.4 Scenario 483 SCHELL Model93.1 Definition93.

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2 SCHELL Model Interfaces93.3 The SCHELL Tool103.3.1 Liveware-Hardware (L-H)103.3.2 Liveware-Software (L-S)103.3.

3 Liveware-Environment (L-E)103.3.4 Liveware-Liveware (L-L)113.4 THE SHELL TOOL113.

5 Analysis of Incident 3133.5.1 The Liveware-Software interrelationship133.5.2 The Liveware-Hardware interrelationship143.5.

3 The Liveware-Environment interrelationship153.5.4 The Liveware-Liveware interrelationship4.

CONCLUSION175. REFERENCES18List of Figures3.1 SHELL diagram123.

2 SCHELL diagram12Executive SummaryAir transportation is a dynamic structure consisting of three core complex subsystems. Airlines, airports, and air traffic control service are independent, yet highly interactive, entities that include human management, policies and procedures, equipment and resources. Avoiding errors in this intricate network is core concern in aviation but despite major advances in air transportation safety systems services, fatal accidents still occur frequently (Schmitt & Gollnick, 2016). Recent crashes, such as Asiana Flight 214 in July 2013, a Boeing 777 miscalculated the landing clipping a sea wall causing the aircraft to crash and burst into flames causing three fatalities and multiple injured. Pilot fatigue was one of the contributing human factors along with over reliance on automation (Taylor, 2013).

In December 2016 Columbian civil aviation regulators stated that an accident involving an Avro RJ85, a charter plane operated by LAMIA Bolivia, was due to a combination of errors of the pilot, charter plane operator and Bolivian aviation authorities. “No technical factor was part of the accident, everything involved human error….” resulting in the fatalities of 71 of the 77 passengers (Bellamy, 2016).

There are other factors that contribute to accidents such as weather, environmental issues, aircraft age and many others but the simplicity of these two accidents highlight the significance of human factor and the importance of flight safety systems. This report will demonstrate my understanding the human factors referred to as “The Dirty Dozen “and the SHELL safety model. I will show how human factors contributed to accidents in which I was personally involved and retrospectively discuss the benefits of the SCHELL model. INTRODUCTION1.

1 DefinitionErgonomics (or human factors) 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 other methods to design in order to optimize human well-being and overall system performance (International Ergonomics Association, 2000).1.2 Human Performance in MaintenanceMotivated by a disproportionately high number of maintenance-related incidents and accidents in the 1980s and the 1990s, the aviation industry and Transport Canada, developed Human Performance in Maintenance (HPIM) training, aimed to address maintenance error. In 1993 Gordon Dupont, a Special Programs Coordinator for Transport Canada, developed a concept “The Dirty Dozen” that formed part of the training program and has since become a key element in aviation training courses (Ahasan, Shahren, Haque & Islam, 2017).

1.3 The Dirty DozenThe “Dirty Dozen” is a series of safety awareness posters designed to draw attention to twelve human error preconditions that have been identified as precursors to accidents and incidents –Lack of communication Lack of team work Norms Pressure Complacency Lack of knowledge Lack of awareness Lack of resources Distraction Assertiveness Fatigue Stress(ICAO, 2013).Theories such as James Reason’s ‘Swiss Cheese’ model were primary contributors to the development of organisational safety systems. These theorists recognised the importance of the considering elements of human behaviour and human error when designing complex systems to avoid potential disaster (Schmitt ; Gollnick,2016).2. SCENARIOS2.1 SCENARIO (1)Incident: Hydroplaning.Age of driver: 18Sex of driver: maleNumber of occupants: 2Type of vehicle: Holden SV6 uteTime of incident: 0400hrsWeather: RainingDirty Dozen Contributory Factor:  Lack of Knowledge Summary: The accident occurred along a section of the Bruce Highway approximately 26k south of Tully.

I was a passenger in a vehicle driving north from Brisbane through to Cairns. The weather had been poor and there had been heavy downpours in the previous four hours leaving pools of water on the road. The speed limit was 100km and the driver was travelling at that speed attempting to make up time from delays. The driver had been in operation for nearly 17 hours when the vehicle hit a large pool of water on the road and suddenly pulled to the left leaving causing him to react by applying the brakes heavily and sharply steering to the right. The car skidded sideways veering off the road. The vehicle came to a stop approximately 20 metres off the highway, impacting the front of the car with a drain embankment. No one in the vehicle sustained any physical injuries.

, both myself self-extricating the vehicle.The impact with the embankment resulted in a punctured front passenger side tyre and minor vehicle panel damage. There was moderate damage to front of vehicle including radiator damage. The vehicle was not able to be driven back on to the road due to the saturated ground condition, steep embankment and damage.Other contributing factors:Lack of knowledge including inexperience Operation of the vehicle at inappropriate speed for the road conditions.Lack of driving skills for wet road conditions Failure to carry out an action or task when action was requiredKnowledge-based errors – Mistakes and poor judgment.

Driving is a complex and multidimensional skill that involves the operator to acquire and consolidate vehicle operation determinants such driver capability, operational demands and road traffic specifics. Lack of knowledge from inexperience doesn’t allow for visual and cognitive recognition of risks (Pereira DaSilva, Almeida-Santos, & Meireles, 2014). When a driver’s knowledge and ability doesn’t meet task demands, the risk for incident increases. Drivers begin with basic competences of vehicle operation but experience gained over time allow them to develop the intricate reasoning and perceptive skills required (Berg,2006). 2.2 SCENARIO (2)Incident: T-bone collisionAge of driver: 36Sex of driver: femaleNumber of occupants: 2Type of vehicle: Holden SV6 uteTime of incident: 1730hrsWeather: FineDirty Dozen Contributory Factor: StressSummary: This accident occurred at approximately 1730hrs on Annandale Rd. I was a passenger in a vehicle traveling 50klm/hr when the driver has missed the required right turn.

The driver made a hasty decision to turn right at the next street and indicated to do so. While indicating right the driver moved wide toward the left before proceeding into the turn. Another vehicle travelling north, then collided with the driver’s side rear wheel, causing moderate panel and wheel damage.

The car was unable to be driven due to damage to the rear wheel. None of the occupants in either car sustained any injuries. Other contributing factors: Mental fatigue -; poor decision making.

Distraction caused by phycological overloadIncreased emotional stress Stress is a major contributor of road traf?c accidents. Mental distractions such as worry, irritation or anxiety, diverts attention away from the driving task. Stress causes physiological changes in an individual and influences the distribution of attention, awareness, attentiveness and decision making. Driving requires continual physical and perceptive focus for changes in the environment to recognise potential hazards. Mental overload results in a decrease in capabilities and subsequently increases chance of an accident (Taylor ; Dorn, 2006).2.3 SCENARIO (3)Incident: 4X4 Age of driver: 14Sex of driver: maleNumber of occupants: 2Type of vehicle: Nissan Patrol 4x4Time of incident: 1000hrsWeather: Raining heavily. Dirty Dozen Contributory Factor: Lack of Communication.

Summary: The incident took place on a cattle station in rural Far North Queensland. I was the driver of a 4WD utility heavily loaded with farming equipment. Due to an early wet season several hundred head of cattle had to be quickly moved to avoid stranding in an area of low food. I was tasked with driving and everyone else was on horseback.

Customarily, due to my young age at the time, my Grandfather would ready the vehicle, securing the load and locking in the hubs to avoid any risk of being forgotten. On this day as per normal I was aware of him checking the vehicle. I received departure instructions to use 4WD at the entrance of creek crossings. At about a third of the way along the route I entered into a sandy crossing, resulting in the vehicle bogging deep to the differential. I attempted to gear down into a lower drive when I realised that the 4WD aspect was not engaged and the hubs had not been locked on.

This left me and the vehicle stranded in a creek crossing with rising water. Later I discovered that my Grandfather had intended that I do this task myself, confidant I was capable as I had done this simple task many times. Due to a consistent routine I was inattentive to the instructions assuming it had been done as normal.Other contributing factors:Lack of communication concerning changed circumstances,Authority relationships influencing communication climate.2.

4 SCENARIO (4)Incident: Falling asleep at the wheel.Age of driver: 40Sex of driver: maleNumber of occupants: 2Type of vehicle: KENWORTH Prime mover multi-trailer road train – 600HP Time of incident: 0310hrsWeather: FinePotential Dirty Dozen Contributory Factors: FatigueSummary: This incident occurred along a long stretch of the Stuart Highway in the Northern Territory. I was a passenger in a Semi doing hauls between Northern Territory and Western Australia. The driver was on a return trip, nearing the end of his 8th 12-hour shift.

The semi was speed limited to 110klm/hr and was travelling close to that speed when the driver fell asleep, veering off the road. The truck and trailer rolled onto the driver’s side, skidding along the dirt for approximately 100 meters. Fatigue results in reduced action in the central nervous system (CNS), peripheral nervous system and skeletal muscle. This causes reduced coordination, cognitive ability, awareness and mindfulness, memory lapses and many other deficits that increase error and contribute to accidents (Abd-Elfattah, Abdelazeim & Elshennawy, 2015).20% of accidents on highways and 30% of motor vehicle fatalities have been contributed to fatigue. Recent studies claim fatigue is comparable to being intoxicated and 17-18 hours without sleep is equivalent to having a blood alcohol level of 0.05% (the legal limit for driving) and 24 hours compares with a blood alcohol level of 0.

1% (Higgins et al, 2017).3. SCHELL MODEL 3.1 DefinitionThe SHELL Model is defined as “the relationship of human factors and the aviation environment” (Reinhart, 1996).The SHELL model describes the contextual associations between infrastructure, human behaviour and other essentials of the workplace environment and suggests the human component is not a solitary cause in an Incident.

The SHELL model considers both active and dormant defects in the aviation system (ICAO, 2013).3.2 SCHELL ComponentsThe components of SCHELL are- Software –  The rules, procedures and written documents such as aeronautical, maintenance procedures and manuals which are part of the standard operating procedures. Cultural element — The elements of human culture and organisational culture. Shared beliefs, values and norms of an individual or group. Hardware – The functional systems including equipment, components, cables, antennas and accessories, configuration, controls and surfaces, displays.Environment – The social, economic and natural climate or environment, including weather, noise, Liveware – The “YOU” central human element such as the pilot, flight crews, engineers, maintenance personnel, management and administration people. Liveware – The interactions of “OTHERS” human factors such as the communication between maintenance personnel and engineers, flight crews and pilots etc.

(ICAO, 2013).3.3 SCHELL Model Interfaces3.3.1 Liveware-Hardware (L-H) – This is the interaction between the human aspect and machine.

(L-H) involves considering a task to be performed and comparing the physical components of equipment with characteristics of human operators. An example is seating designs complimentary to human posture. 3.3.2 Liveware-Software (L-S) – (L-S) focuses on the association between an individual and the operational systems found in the workplace.

(L-S) involves software, regulations, manuals etc designed in accordance to capabilities of human users implementing these structures. 3.3.3 Liveware-Environment (L-E) – This interface looks at the human operator and workplace environments.

Factors associated with the internal environment are temperature, light, noise, ventilation and external factors such as visibility, turbulence and topography. Considerations include adapting the environment to match normal biological requirements such as lighting and temperature controls to aid sleep, pressurised cabins. Errors occur when there is a mismatch such as visual illusions at night or interrupted sleep cycles. 3.3.4 Liveware-Liveware (L-L) – The (L-L) interface emphasises individual operator concomitance with other persons relevant to performing tasks. Interrelationships between individuals and also within groups such as ground crew, flight crew, maintenance, managers, passengers etc can affect behaviour and performance. Examples are managerial, teamwork, and organisational cultures.

Mismatches occur via poor communication techniques and systems resulting in poor information exchanges or a lack of leadership. (Cacciabue & Vella, 2010), (DASS Publication, 2007), (ICAO, 2013)3.4 THE SHELL TOOLThe SHELL diagram is used as a visual tool.

The interactions are represented in the layout of the components. Liveware (Human) is central to the SHELL model of Human Factors and only interfaces with a liveware component are considered. The edges of the liveware block are “rough” and represent the unpredictability of humans.

This volatility at the interfaces need to be understood to avoid systemic fractures (DASS Publication, 2007).Figure 3.1 The SHELL model – components and interfaces Figure 3.2 The SCHELL model3.5 Analysis of Incident 3The liveware, is the central element of the model, and represents myself as I am the driver of the vehicle. The second liveware component is my Grandfather, who, contributed to the onset of the occurrence. The liveware i.e.

myself, is the most important factor of the SHELL model. My physical performance is individual, controlled by physical size and strength, physiological needs, my intellect and ability to receive and process information, my reactions, memory, coping mechanisms and tolerance of environmental conditions. Because of these human characteristics liveware is somewhat unstable. In scenario 3 software represents training, experience, skills, knowledge, instructions, and supervision.

Hardware is the vehicle and equipment and environment represent the weather, terrain, obstacles and time of day. 3.5.1 The Liveware-Software interrelationshipInsufficient training Limited type rating training Insufficient basic training Insufficient 4WD trainingLimited driving experience Limited driving experience with the vehicle type Limited total driving experience. Limited recent driving experience.

Limited driving experience with regard to 4WD evasive actionPoor driving skills The driver did not recognise the symptoms of an impending bogThe driver insufficiently monitored speed The driver didn’t have adequate control of the vehicle at pathThe driver did not have sufficient control of the vehicle approaching the sandy crossing The driver had a rough driving styleUnsound course of action The driver failed to engage in inspection or checks prior to departureThe driver did not check the sandy crossing by first physically inspecting vital conditions The driver selected an unsuitable route The driver failed to consider weight of loadThe driver (myself) had no formal driving training. Driving skills consisted of few informal experiences in rural settings. Prior 4WD experience involved a smaller vehicle. The driver had only operated the 4WD component on the vehicle in this incident three other times had been in the company and under direction of an adult. The terrain encountered on the day was challenging, and the driver did not have sufficient knowledge or exposure with the characteristics of creek crossings.

The driver failed to inspect the creek crossing by walking it to assess for dips or drop-offs, obstacles and the integrity of the driving surface. The driver selected low range understanding the requirement of gentle torque delivery in maintaining a slow steady speed but failed to notice that the 4WD indicator light on the dash was not on. Before proceeding into the creek crossing the driver did not consider vital components of driving in water/sand. Elements of 4WDing such as tyre pressure, load weight, route, access and egress etc were not considered.As the driver had no experience in this type of situation he failed to recognise the risk and signs of bogging. When the vehicle began to sink in the creek crossing the driver made a correct choice of continuing on at same momentum. The drivers course of action thereafter of revving and spinning wheels in attempt to exit the bog exacerbated the situation.

3.5.2 The Liveware-Hardware interrelationshipPoor manufacture There was no fault with the vehiclePoor repair skills Tyre pressure not altered to successfully cross sandy terrainDriver failed to adjust driving seat for optimal viewIncorrect loading Tyre pressure was incorrect for weightPoor skills in use of equipment Driver failed to notice the omission of 4WD indicator lightDriver failed to engage 4WDDriver failed to consider causes of failureDriver did Use rescue equipmentThe driver focused his attention on the visual aspect of the creek crossing neglecting to consider other essential factors. The driver’s knowledge of 4WD techniques was limited and didn’t have the capacity to adequately assess risks and equipment specifications. The driver failed to consider excessive weight and manoeuvrability and controllability of a vehicle. Failing to notice the lack of indicator was a main contributor to this incident. The flow on effect was the driver did not remedy the situation and engage 4WD.

Once the vehicle was bogged the driver failed to assess for causes. Rescue equipment, such as winches and treads were used to remedy the situation. 3.5.

3 The Liveware-Environment interrelationshipMeteorological conditions Heavy rain Decreased lighting conditions Environmental factors.HasteHeavy rain made the driving conditions unfavourable and influenced the driver’s actions and decisions negatively. The failure of the driver to exit the vehicle and check the crossing was likely influenced by the weather. The constant heavy rainfall potentially degraded the creek crossing. The time of day was optimal the rain decreased lighting and visibility.

3.5.4 The Liveware-Liveware interrelationshipPoor communication Misunderstanding Other failure in communicationThe driver failed to join the inspection of the vehicle which contributed to a lack of information. The misunderstanding regarding the wheel hubs was a primary contributor to this incident and may have not occurred if the driver and Grandfather had of inspected the vehicle together.4. CONCLUSIONThe SCHELL model is a useful guide in the investigation accidents and incidents ensuring comprehensive review. The fundamental purpose of the SHELL model is to understand the interaction between individuals, the structures in which they perform and the environment which effects activities. Inspecting the interrelationships among the various components of the aviation system allows analysis of the operating context in which humans make errors.

With the rate of performance errors still having a high human origin safety management remains imperative. Information concerning human performance competences, limits and actions in the operational setting lend insight into developing safety management and theoretical models, like SHELL, facilitate access to that information.5. REFERENCESAbd-Elfattah, H., Abdelazeim, F. and Elshennawy, S (2015). Physical and cognitive consequences of fatigue: A review.

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& Islam, E (2017). Concept of Dirty Dozen: The Silent Killers of Human Factor Errors and Mistakes. Ergonomics International Journal. Retrieved from: https://medwinpublishers.

com/EOIJ/EOIJ16000137.pdfBellamy, W (2016) Colombia Plane Crash Caused by Human Error. Aviation today. Retrieved from:, H (2006).

Reducing crashes and injuries among young drivers: what kind of prevention should we be focusing on? Injury Prevention. (12) 1. doi:10.1136/ip.2006.012062Cacciabue, P & Vella, G (2010). Human factors engineering in healthcare systems: The problem of human error and accident management.

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& Rosekind, M (2017). Asleep at the Wheel—The Road to Addressing Drowsy Driving. Sleep journal, (40) 2.

1093/sleep/zsx001 ICAO (2013). Doc 9859 Safety Management Manual (SMM) (3rd Ed). Montreal: International Civil Aviation OrganisationPereira da Silva, F., Almeida-Santos, J. & Meireles, A (2014). Road Accident: Driver Behaviour, Learning and Driving Task. Procedia – social and behavioural sciences.

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DOI:10.1007/978-3-7091-1880-1Taylor, A (2013) The Crash of Asiana Airlines Flight 214. The Atlantic. Retrieved from:, A & Dorn, L (2006). Stress, Fatigue, Health, and Risk of Road Traffic Accidents Among Professional Drivers.

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