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Airside Operations Safety: Understanding the Effects of Human Factors (2022)

Chapter: Chapter 6 - Managing Fatigue Risk

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Suggested Citation:"Chapter 6 - Managing Fatigue Risk." National Academies of Sciences, Engineering, and Medicine. 2022. Airside Operations Safety: Understanding the Effects of Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/26779.
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Suggested Citation:"Chapter 6 - Managing Fatigue Risk." National Academies of Sciences, Engineering, and Medicine. 2022. Airside Operations Safety: Understanding the Effects of Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/26779.
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Suggested Citation:"Chapter 6 - Managing Fatigue Risk." National Academies of Sciences, Engineering, and Medicine. 2022. Airside Operations Safety: Understanding the Effects of Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/26779.
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Suggested Citation:"Chapter 6 - Managing Fatigue Risk." National Academies of Sciences, Engineering, and Medicine. 2022. Airside Operations Safety: Understanding the Effects of Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/26779.
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Suggested Citation:"Chapter 6 - Managing Fatigue Risk." National Academies of Sciences, Engineering, and Medicine. 2022. Airside Operations Safety: Understanding the Effects of Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/26779.
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Suggested Citation:"Chapter 6 - Managing Fatigue Risk." National Academies of Sciences, Engineering, and Medicine. 2022. Airside Operations Safety: Understanding the Effects of Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/26779.
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Suggested Citation:"Chapter 6 - Managing Fatigue Risk." National Academies of Sciences, Engineering, and Medicine. 2022. Airside Operations Safety: Understanding the Effects of Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/26779.
×
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Suggested Citation:"Chapter 6 - Managing Fatigue Risk." National Academies of Sciences, Engineering, and Medicine. 2022. Airside Operations Safety: Understanding the Effects of Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/26779.
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36 Managing Fatigue Risk The word “fatigue” refers to a feeling of tiredness due to mental or physical exertion. In the field of aviation safety, this type of fatigue is most often referenced as “cognitive fatigue,” which is degraded brain function due to a lack of proper sleep. The U.S. Centers for Disease Control and Prevention has stated that 30% of workers in the United States sleep less than 6 hours per day (Luckhaupt, 2012). For some people, 6 hours of sleep is the right amount to rejuvenate the brain and allow for optimum mental performance. However, as multiple studies have shown, the amount of sleep an average person needs is around 8 hours per night. Therefore, it is likely that many airside personnel are performing below their optimum capability due to a lack of sleep. However, during the analysis of the V/PD data, only five of the 847 V/PD events referenced fatigue as a cause. This was surprising, in one respect, since one of the preconditions for decision errors and violations per the HFACS taxonomy is the condition of the operator, which includes how fatigue contributes to adverse mental states, mental limitations, and fitness for duty. The small number of V/PD events citing fatigue prevented generalized determination of the risks air- ports face from fatigued workers. Fatigue risk will vary from airport to airport depending on factors such as the size of the staff and the tempo of operations. Airport leaders knowledgeable in the area of fatigue and its impact on performance can use this knowledge to help mitigate the risks associated with this safety hazard. This chapter provides high-level information airport leaders can use to heighten awareness of fatigue as a human factor that affects airside performance; the chapter also directs leaders toward resources available to develop risk mitigations. Fatigue impacts on airside personnel and the degree to which fatigue is a high-risk issue is a subject ripe for its own research study. This chapter provides a baseline of knowledge on which an airport manager can create a fatigue risk management program (FRMP) that fits the needs of the organization. 6.1 Background Fatigued workers perform at a lower level and make more errors than their teammates who are well rested. The FAA has sponsored studies on the effects of fatigue, but these efforts have focused on aircrew, aircraft maintenance personnel, and air traffic controllers— groups that arguably have the most direct impact on flight safety. However, the research C H A P T E R   6 To manage fatigue risk and combat the frequency of decision errors, leaders and airside personnel should have a grasp on a few key concepts regarding fatigue and sleep: fatigued performance equates to intoxicated performance, sleep debt is cumulative and insidious, and recovery from sleep debt can take a week or longer.

Managing Fatigue Risk 37   team was unable to find any research related to airport personnel working in the airside environment. 6.1.1 Aviation Industry Fatigue Research Airport leaders looking to reduce fatigue risk in their personnel will find that research related to aircraft maintenance personnel is likely the most relevant and relatable. Additionally, all commercial air carriers certificated under 14 Code of Federal Regulations (CFR) Part 121 are required to submit an FRMP for review and approval by the FAA. Tenant airlines may be a readily available resource for airport leaders to explore for examples and lessons learned on the implementation of fatigue risk-mitigation strategies. 6.1.2 Fatigue Risk Management in Package Delivery During the project, and given its focus on V/PDs and airside driving, the researchers postu- lated that organizations that operate aircraft and surface vehicles for cargo and passage delivery would be valuable resources for FRMP lessons, from which airports could learn and apply these lessons to airside drivers. However, after interviewing multiple major cargo and passage delivery companies, it was found that these companies do not typically share approaches to fatigue across lines of business. The motivation for having an FRMP in place was strongly influenced by regulatory requirements; the requirements are detailed and more prescriptive for pilots, whereas regulations for the driving side do not go much beyond limiting the hours of continuous driving prior to rest. 6.1.3 Addressing Fatigue to Reduce Decision Errors While the findings from the V/PD data analysis did not suggest that fatigue was a direct cause of these hazardous events, addressing fatigue as a mitigation strategy makes perfect sense given the plethora of research and data on the subject. What the findings do suggest, given the lack of investigative results indicating fatigue, is that an awareness of the causes and impacts of fatigue should exist at airports across the country. Implementing FRM strategies may be a sound starting point for reducing decision errors. The only long-term solution for fatigued workers is for them to have a full night’s sleep every night. While there are technologies that allow individuals and organizations to monitor the duration and quality of sleep, it remains the responsibility of individuals to guarantee that they are fit for duty. Once airside workers are made aware of the link of decision errors to V/PDs and safety incidents and are made aware of the contribution fatigue plays in decision errors, the seed is planted for individual workers to change behaviors and sleep patterns. The process can start with including fatigue awareness topics in airport driver training pro- grams, as suggested in Chapter 5. Additionally, airports may consider implementing tech- nologies to monitor the sleep patterns of employees on a voluntary basis to assess the level of risk fatigue presents. Such technologies are discussed in Chapter 7. Airports can also use effective safety investigation techniques to determine whether fatigue was a cause in airport safety incidents, not only when investigating V/PDs (rare events for all air- ports), but for any safety hazard or issue identified by airport personnel. Investigations are covered in Chapter 8, while these and other strategies are discussed in the remainder of this chapter. Proactive approaches, coupled with heightened awareness of fatigue risk, can reduce the risk of human error during any extended irregular operations.

38 Airside Operations Safety: Understanding the Effects of Human Factors 6.2 Three Fatigue Concepts Airside Personnel Should Understand To manage fatigue risk more effectively and, therefore, combat the frequency of decision error, leaders and airside personnel should have a grasp on a few key concepts regarding fatigue and sleep: • Fatigued performance equates to intoxicated performance. • Sleep debt is cumulative and difficult to recognize. • Recovery from sleep debt can take a week or longer. These three concepts are easy to remember and relatable. They can form the basis for a train- ing module aimed at those involved in airside operations and lead to an expanded interest and a better understanding of human factors. 6.2.1 Fatigue Versus Intoxication – Their Similar Impacts on Cognitive Performance In the early 2000s, research findings began to circulate in the aviation industry that showed the relationship between cognitive performance (effective brain response and decision making) in fatigued persons and persons experiencing intoxication. 6.2.1.1 Heightening Awareness Using a Familiar Situation At the Naval School of Aviation Safety, then resident at the Naval Postgraduate School, the faculty integrated various research findings on the relationship between fatigued performance and intoxicated performance into the safety curriculum for both aviation squadron command- ing officers and aviation safety officers. The reasoning behind this decision was that aviators and aviation maintenance personnel lacked an understanding of the impacts of fatigue, feeling that fatigue was a condition a person could and would work through without thinking twice, whereas working while under the influ- ence of alcohol was not only well understood, but also violated regulations and was not accepted by anyone in a naval aviation squadron. Thus, bringing to light the connection between working or flying while fatigued and performing the same tasks while intoxicated would heighten aware- ness to a key influence on cognitive abilities and decision making. 6.2.1.2 What Is the Impact of Fatigue on Brain Performance? Studies comparing response speeds during psycho motor vigilance tests (such as measuring the time it takes to press a switch after seeing a light illuminate) showed the following relationships (Williamson and Feyer, 2000): • After 17 to 19 hours without sleep, brain responses were equiva- lent or worse than those at a blood alcohol concentration (BAC) of 0.05%. • After longer periods, around 22 to 24 hours without sleep, brain perfor- mance was equivalent to that at BACs of between 0.08% and 0.1%. In other words, at the end of an extra-long shift or during irregular operations requiring continuous operations (such as snow-removal operations), those still on the job can be con- sidered as performing as if they were legally intoxicated and in jeopardy of losing their driving privileges on public roadways. Brain performance after 22 to 24 hours without sleep is equivalent to that when a person’s blood-alcohol content is between 0.08% and 0.1%, which is above the legal limit for operating a motor vehicle on public roads.

Managing Fatigue Risk 39   6.2.2 Sleep Debt: It Accumulates Over Time and Is Hard to Recognize Research has consistently shown that the average adult needs 8 hours of sleep each night. However, everyone is different, and the amount of sleep that individuals need to fully refresh their brain varies. In simple terms, the brain is a complex computer that needs to shut down and update every night. The brain is refreshed and recharged during sleep. If the proper amount of time required to refresh and recharge is interrupted, the performance of the computer is degraded. 6.2.2.1 Defining Sleep Needed and Sleep Debt The amount of sleep needed to fully recharge is known in the scientific field as the “optimum sleep duration” (OSD). The amount of sleep a person typically gets at home each night is known as “habitual sleep duration” (HSD). The difference between a person’s OSD and HSD is known as “potential sleep debt” (PSD) (Kitamura et al., 2016). PSD is an important concept because it is an indicator of restricted sleep in the individual. Individuals experience restricted sleep when they do not achieve their required amount of sleep each night over a period of time. Given that the Centers for Disease Control and Prevention (Kitamura et al., 2016) estimate that 30% of the working population sleeps fewer than 6 hours per night, or 2 hours below the average OSD, it is highly likely that a significant percentage of airside workers are experiencing restricted sleep and accumulating PSD. Sleep debt is cumulative. However, people adapt to the sleep they are used to getting, or their HSD. Thus, individuals in the field, without determining the optimum amount of sleep they actually need, become accustomed to how they feel and how they perform. They are thus unable to recognize that they are performing at a lower level due to their chronic fatigued state. 6.2.2.2 How Does Sleep Debt Affect Cognitive Performance? Figure 6-1 illustrates the results of research that studied cognitive performance differences in persons whose sleep was restricted to varying degrees. The results shown are for different groups of people who were allowed different durations of sleep over a 7-day testing period (Days E1 through E7). One group was given the opportunity to sleep for a maximum of 9 hours, another group allowed to sleep for 7 hours, and two other groups allowed 5 hours and 3 hours of sleep, respectively. Their performance was measured using a psychomotor vigilance test, measuring the time to respond to a stimulus—that is, the person’s reaction speed. The mean speed shown on the y-axis of the chart is an inverse relationship, meaning the higher the score, the faster the reaction and thus the higher the level of brain performance (Belenky et al., 2003). The significant degradations in performance for those allowed only 3 and 5 hours of sleep are not surprising. What is of particular interest in this study is that the response scores of the group that was allowed to get 7 hours of sleep each night were roughly 7% below their fully rested baseline scores (scores on Day B). This means that those working airside who typically sleep for 7 hours or less each night are likely performing at or perhaps below 90% of their full capabilities. Therefore, the risk of decision errors is higher in personnel dealing with levels of chronic fatigue due to restricted sleep and accumulated sleep debt. 6.2.3 Recovering from Sleep Debt – It Takes Longer Than a Weekend Consider the following scenario: after a long week of high-tempo operations requiring extended shifts to keep the airport open and fully functional, an airport employee authorized to operate Sleep debt is cumulative. Individuals in the field, without determining the optimum amount of sleep they actually need, become accustomed to how they feel and how they perform. Thus they are unable to recognize that they are performing at a lower level due to their chronic fatigued state.

40 Airside Operations Safety: Understanding the Effects of Human Factors vehicles in the movement area heads home for a weekend with the morning alarm turned off. After 2 days of longer-than-usual periods of sleep, the employee heads to the airport on Monday feeling refreshed and ready to perform at 100%. However, as good as this person may feel, studies show that the employee is not ready to operate at 100% of mental capacity. 6.2.3.1 Recovery Time Depends on the Extent of Sleep Restriction Looking at Figure 6-1, those involved in the sleep restriction study were observed during a 3-day recovery period (Days R1 through R3) where they were afforded as much sleep as they desired. Again, their response times were recorded for the psychomotor vigilance test each day. During this study, none of the participants recovered to a level of performance equal to their baseline scores. In this study, the scores improved on the first day of recovery but then leveled out on the next 2 days. This would indicate that a weekend after an extended period of less-than-optimal sleep each night is not sufficient to allow the brain to fully recover. 6.2.3.2 Time Required to Fully Recover from Sleep Debt As presented previously, sleep debt is the difference between optimum sleep duration and the sleep duration on a particular night (PSD = OSD – HSD). For example, a person whose optimum amount of sleep is 8 hours per night and who gets 7 hours of sleep on a particular night has accumulated 1 hour of sleep debt. If that person sleeps 7 hours a night for the next 5 nights, their sleep debt would then be 6 hours. During a sleep study where researchers studied OSD and the amount of sleep necessary to recover from sleep debt, to establish the optimum amount of nightly sleep for each person, healthy study participants were provided the opportunity to sleep 12 hours per night for 9 consecutive days (Kitamura et al., 2016). The researchers then studied the sleep debt recovery times needed to improve several physiological and cognitive metrics. The researchers found that it could take as many as 4 days to Notes: RT = reaction time, HR = hours. Source: Belenky et al., 2003. Figure 6-1. Psychomotor vigilance task speed for various levels of restricted sleep and during recovery. Research has shown that it may take as many as 4 days to fully recover from 1 hour of sleep debt.

Managing Fatigue Risk 41   fully recover from 1 hour of sleep debt. Cognitive capabilities tended to recover more rapidly, but other health-related metrics lagged, and additional days of extended sleep were needed to reach the levels measured when subjects achieved their optimum level of sleep. The key takeaways from the study were that healthy young adults typically were not aware that they experienced problems sleeping, that they were on average accumulating 1 hour of sleep debt each night, and that they needed up to 9 days of sufficient sleep to fully eliminate their accumulated sleep debt. 6.3 Fatigue and Irregular Operations – Practices to Mitigate Risks During normal operations, an airport manager may determine that fatigue risk is manageable given that most employees work in shifts and keep regular hours. Where the risk of human error is likely to surface for any airport is during irregular operations (IROPS). With this in mind, the research team interviewed representatives from 10 airports during the final phase of the project to explore approaches for managing fatigue risk during extended snow-removal operations. Fatigue was a topic each airport addressed, typically during pre–snow-season briefings. Several of the airports had active mitigation strategies in place. Some of the approaches to reducing fatigue risk during snow operations are discussed in the following: • Maximum Time on Duty Standards. This approach involves establishing a maximum time that a single employee can be on duty and operating snow-removal equipment. The most common maximum shift length was 18 hours. • Adjusting Work Hours in Advance of a Storm. Airport managers observe the weather forecast and adjust working hours for snow team members to get adequate sleep prior to the start of snow-removal operations. • Reserving Hotel Rooms Near the Airport. This approach provides airport employees a place to sleep between shifts, thus eliminating long commutes and potentially hazardous driving conditions while fatigued. • Setting Up a Break Room on the Airport. This approach is implemented less often, but some airports have a specific space set up as sleeping quarters, complete with bedding, blackout curtains, food, and drink. Others configure conference rooms with cots to serve as temporary rest facilities. Such proactive approaches, coupled with heightened awareness of fatigue risk for airport leaders and employees, can work effectively to reduce the risk of human error due to fatigue, not only during snow-removal operations but during any extended irregular operations. 6.4 Developing Airport Programs to Manage Fatigue Risk There are options that airports of various sizes and complexities of operations can consider when looking to address fatigue risk. For large commercial airports, it may be practical to develop and implement an FRMP, while small airports with limited staff and resources may choose to mitigate risk through awareness training added to airside driver training programs. Whatever approach is taken, resources are available to assist airport leaders. 6.4.1 Fatigue Risk Management Programs In 2010, the FAA began requiring commercial airlines certificated under 14 CFR Part 121 to submit an FRMP for approval. Such programs address the risks associated with operating

42 Airside Operations Safety: Understanding the Effects of Human Factors while fatigued and outline the organization’s mitigation strategies to reduce the levels of risk. The FRMP is developed and implemented across the organization, with the plan addressing key topics such as: • Organizational responsibilities and requirements; • Limitations on working hours and flight time; • Fatigue concepts and definitions; • Organizational education and training programs; and • Fatigue identification, risk assessment, and monitoring processes. Airline FRMP development follows information published by the FAA and ICAO in the following documents: • FAA Advisory Circular 120-100: Basics of Aviation Fatigue • FAA Advisory Circular 120-103A: Fatigue Risk Management Systems for Aviation Safety • ICAO: Fatigue Management Guide for Airline Operators, Second Edition, 2015 These documents focus on pilots, but the concepts and structures of the programs can be adapted to fit the airport model if leaders determine that they have the resources and staff available to support such an enterprise-wide effort. Airports following this path may also benefit from additional information on how the FAA addresses fatigue risk management for aviation maintenance organizations and personnel. The information found in the following document, while not directly aimed at airports because the focus is on those that support flight operations on the ground, could also be helpful to airports: • FAA Advisory Circular 120-115: Maintainer Fatigue Risk Management 6.4.2 Fatigue Risk Management Awareness Training For smaller airports and those that determine that the risk posed by fatigued employees is low, an effective approach may lie in integrating fatigue risk management elements into existing training programs (such as airside driver training) or developing a standalone training course to heighten awareness for all employees. Such efforts could not only reduce the levels of risk from decision errors in the airside environment but could also aid in the improvement of employee health and safety in general. 6.4.2.1 Representative Topics to Include in Training For airports desiring to go beyond the key topics discussed in Section 6.2 to develop a more comprehensive fatigue training module, the course outline illustrated in Table 6-1 can serve as a starting point. This outline follows a sequence of topics similar to a self-training program used by a major air carrier. Topic Training Elements Policy Airport policy, regulations, and rules related to sleep, rest, and fatigue Basics Basics of fatigue, to include sleep fundamentals, circadian rhythms, and night-shift work Causes Causes and awareness of fatigue Effects Effects of fatigue on human performance and decision making Approaches Fatigue countermeasures, prevention, and mitigation Influences Influences of lifestyle, including nutrition, exercise, and family life, on sleep and fatigue Health Impacts of chronic fatigue on health Disorders Sleep disorders, including recognition, health impacts, and treatments Reporting Responsibilities and procedures for self-reporting fatigue or reporting fatigue identified in others Table 6-1. Sample fatigue awareness training course outline.

Managing Fatigue Risk 43   6.4.2.2 Fatigue Training Content Resources Resources are available to assist airports with developing training materials on fatigue. The content included can be as extensive as the organization desires or the need requires. Two sources available on the Internet with sound summaries of key topics are: • National Safety Council (https://www.nsc.org/work-safety/safety-topics/fatigue), and • Canadian Centre for Occupational Health and Safety (https://www.ccohs.ca/oshanswers/ psychosocial/fatigue.html). One U.S. airport operations supervisor interviewed during the research explained how he used the course information made available on the National Safety Council website as the foundation for a dedicated training module on fatigue and managing fatigue risk, then added specific local information as case studies to make the concepts relatable to local employees. The information on the Canadian site is similar to that on the National Safety Council site but has additional detail included from a practical rather than an academic perspective. Together, this information is complementary and provides a sound baseline from which to build an informative educa- tion module. Several fully developed fatigue training courses are available, and some of them are provided online for free. These courses do not have an aviation or airport focus, but the concepts presented can provide a basic level of knowledge on fatigue and sleep that an airport can expand on to address specific organizational and professional topics. Airports Council International (ACI) offers an online course entitled “Human Factors Safety Training” that addresses fatigue in the context of an overarching human factors discussion. This course takes 1.5 hours to complete and is available for $50 to ACI members.

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Despite dedicated efforts involving changes in technologies and procedures, the number of annual runway incursions in the United States has shown little to no improvement.

The TRB Airport Cooperative Research Program's ACRP Research Report 246: Airside Operations Safety: Understanding the Effects of Human Factors provides a review of the current state of human factors research and the related resources that are available to U.S. airport operations personnel.

Supplemental to the report are an Executive Summary (to be released soon) and a White Paper.

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