The NASA Ames Fatigue Countermeasures Group makes great strides to examine the extent to which fatigue, sleep loss, and circadian disruption affect pilot performance.

MallisPilot fatigue is a concern in current aviation operations. As fatigue and sleepiness levels increase, performance becomes less consistent and vigilance deteriorates.1 Surveys, observational data, and anecdotal reports have indicated that it is not uncommon for pilots to experience unintentional episodes of sleep while flying.2-4 Circadian misalignment is inevitable in aviation due to transmeridian travel, which often results in the flight crews working during times when their circadian system is programming their bodies to sleep, and sleeping when their circadian system is programming them to be awake. Scientific research5 has shown that individuals’ judgment of their own level of sleepiness is an unreliable source of fatigue assessment; therefore, pilots cannot accurately assess their level of fatigue. Pilot alertness is further challenged during nighttime flights in highly automated cockpits that require extensive monitoring of displays, yet reduce interaction with aircraft systems. Decreases in alertness and performance reduce the margin of safety and increase the chances of a fatigue-related incident or accident.

Since 1980, the Fatigue Countermeasures Group has been examining the extent to which fatigue, sleep loss, and circadian disruption affect pilot performance. Currently, the group is part of the Systems Safety Research Branch in the Human Factors Research and Technology Division at NASA Ames Research Center, Moffett Field, Calif. When the group was formed in 1980—in response to a Congressional request to examine a possible safety problem of uncertain magnitude due to transmeridian flying and a potential problem due to fatigue in association with various factors found in air transport operations—it was originally named the Fatigue/Jet Lag Program. During the 1980s, its primary research was conducted in field settings with the goal of studying fatigue factors and circadian disruption in short-haul, long-haul, military, cargo, and helicopter operations.6 In 1991, the Fatigue/Jet Lag Program shifted its focus to the development and evaluation of fatigue countermeasures, accident investigation (Guantanamo Bay),7 and aviation policy8; hence, the name was changed to reflect the new focus: Fatigue Countermeasures Group. During the 1990s, the research conducted by the group included field studies of cockpit rest, quantity and quality of on-board sleep, and performance changes associated with augmented long-haul flights. Survey studies were also conducted that examined fatigue factors in corporate and regional airline operations. It was also during the 1990s that the first 2-day Fatigue Education and Training Module (ETM)9 Workshop was conducted to transfer research knowledge to the operational environment. Over the years, the Fatigue Countermeasures Group has continued to interact collaboratively with many government agencies (US Navy, US Air Force, US Army, National Transportation Safety Board, and Federal Aviation Administration) as well as with many academic institutions to conduct laboratory, field, and simulator research; transition the research findings to the operational community; aid in accident investigations; and provide input to policy and regulations relevant to aviation operations. Specifically, the Fatigue Countermeasures Group conducts research focused on detecting, managing, and mitigating changes of alertness and performance that result from sleep loss, fatigue, and/or circadian rhythm disruption associated with flight operations. Today, the research activities focus on three main areas: Countermeasures and Performance, Methodologies and Metrics, and Operational Outreach.

Main Focus
The Countermeasures and Performance focus is in the development and evaluation of strategies for mitigating the effects of sleepiness and circadian disruption on pilot performance and alertness levels. Of particular interest are fatigue countermeasure strategies that can be implemented during flight operations. For example, according to the Federal Aviation Regulations, napping is not allowed on the flight deck and pilots must remain seated; therefore, two studies have been conducted by the Fatigue Countermeasures Group to address the performance-related issues. A commonly cited study, conducted in the 1990s, evaluated the effects of planned cockpit rest vs no cockpit rest during long-haul field operations and found that pilots obtained, on average, a 26-minute sleep period during a 40-minute opportunity (plus a 20-minute recovery). Additionally, 93% were able to fall asleep within less than 6 minutes even though the rest was obtained in the cockpit seat. EEG data revealed that the group that received a 40-minute rest opportunity showed fewer microsleep events after the nap compared to the no-rest group.10 A second study evaluated the effects of planned cockpit activity during simulated long-haul operations. Pilots who received a 7-minute break per hour (standing, stretching, and walking) showed significant reductions for 15 minutes postbreak in physiological data (slow eye movements, theta-band activity, and unintended sleep episodes) and reported significantly greater alertness for up to 25 minutes postbreak when compared to the group that did not receive the regularly scheduled controlled activity breaks.11 Currently, the work continues in the Countermeasures and Performance focus with a study of commercial airline pilots to determine the timing of sleep/wake schedules, light exposures, and subjective alertness ratings during a month of flight activity of both domestic and international carriers.12 In addition, a Web-based Fatigue Counter-measures and Scheduling Survey has been developed to investigate different duty schedules in aviation and related factors contributing to fatigue13 and to evaluate light/dark cycle exposures and scheduling factors that may affect sleep. The data collected in both studies will be used to develop recommendations for optimal rest schedules and light exposures to maximize alertness during both long-haul and short-haul operations.

More Challenges
Another challenge in the aviation environment is the unavailability of objective monitoring in fatigue management systems for use in the detection and monitoring of pilots’ alertness levels. Under the Methodologies and Metrics focus, approaches for the detection and measurement of fatigue are identified, developed, and evaluated for the prediction of alertness changes in flight crews. Development of technologies that objectively provide real-time measures of fatigue and alertness has recently undergone intensified activity due to demands imposed by the unrealistic expectation that individuals can maintain alertness and performance during nonstandard work schedules.14 In 1999, the Fatigue Countermeasures Group conducted a study using a Boeing 747-400 simulator to evaluate the feasibility of incorporating an automated, online, fatigue management technology in the cockpit, and to determine the behavior of pilots in response to such a system. The study showed that it is possible to interface an online, automated drowsiness-detection technology in a full-fidelity simulator flight deck; however, device improvements need to be implemented to achieve specific goals for the aviation environment.

The Fatigue Countermeasures Group has increased its involvement in the development of biomathematical models proposed to be capable of predicting fluctuations in alertness and performance to aid in the development of safe and productive schedules. Currently, collaborations with universities focus on the development of biomathematical models that predict the various factors affecting sleep and waking neurobehavioral performance in the operational environment, and on providing a software version of the model. The goal is to develop scheduling tools that can predict the impact of acute sleep loss, cumulative sleep loss, and circadian desynchrony on waking performance, and providing an indication of the types of work/rest schedules that will minimize fatigue-related events.15 Scheduling tools are being developed independently for both aviation and space operations.15,16

MallisTwo pilots are instrumented for collection of EEG and EOG measures for fatigue and alertness assessment during a simulated flight.

All research conducted by the Fatigue Countermeasures Group is transitioned to the operational environment through the Operational Outreach focus of the group, allowing the research findings to be applied in relevant operational communities. This includes conducting Fatigue ETM Workshops, maintaining an updated Web site (  of all the research findings, as well as providing research materials relevant to specific requests. From 1993 through 2002, a total of 35 two-day Fatigue ETM Workshops have been conducted for 723 participants representing 240 different affiliations and 21 countries. More than half of the respondents to a workshop survey reported that the Fatigue ETM Workshops and materials have provided a basis for change at their organization, and the materials have reached more than 116,000 flight crew and other operational environment personnel.17 Efforts to transition the scientific knowledge to the operational community not only focus on air transport aviation operations but have included regional and general aviation (GA) operations. For example, based on the material used for the 2-day Fatigue ETM Workshops,6 a similar training tool was created for pilots in GA18 focusing on fatigue, sleep, and circadian research specific to the GA community. The materials have recently been transferred to an online Web version to provide relevant information to the GA community and evaluate the effectiveness of the Web-based Fatigue ETM as an alternative method for distribution of the fatigue, sleep, and circadian rhythms research.19

What the Future Holds
All three focuses—Countermeasures and Performance, Methodologies and Metrics, and Operational Outreach—continue to be the main research efforts for the Fatigue Countermeasures Group. Future research efforts in Countermeasures and Performance will continue to explore the effectiveness of countermeasures and other alertness management strategies. Specifically, a new direction will focus on ultra-long-range flight operations. New aircraft capable of flying 20-plus hours are scheduled to enter commercial aviation service in 2004. The Fatigue Countermeasures Group has interacted with the Flight Safety Foundation, Air Transport Association, Boeing, and Airbus to examine the extent of fatigue-related changes associated with such ultra-long-range flight operations. These operations include flight and duty time issues, on-board bunk sleep rostering, crew composition, and strategies to improve alertness and performance. Model development of scheduling software will also continue in the Methodologies and Metrics focus with the final development of software-based tools that can potentially serve as an aid in predicting pilots’ and astronauts’ levels of alertness and neuro-behavioral performance under various conditions.15,16 Such scheduling tools can be used to select flight schedules that will optimize performance. Efforts will also continue in Operational Outreach activities by continuing Fatigue ETM Workshops and by providing input to safety and policy guidelines. Additionally, the Fatigue Countermeasures Group is actively involved with the Mars Exploration Rover (MER) project, a NASA and Jet Propulsion Laboratory joint project. The two Mars Rovers are scheduled to launch in 2003 and the missions require scientists and engineers to work on a Mars day, which is approximately 37 minutes longer than an Earth day. The Fatigue Countermeasures Group conducts Fatigue ETM Workshops specific to MER operations, including the evaluation of schedules and recommendations to improve schedule adaptation and personnel effectiveness.

The Fatigue Countermeasures Group will continue to address the role of physiologically based variations in alertness to develop novel work rules to manage disturbances in operator schedules and circadian rhythms. Additionally, research will continue to identify interventions and to develop technologies to eliminate recurring accidents and human errors resulting from fatigue. Funding for this work is provided by NASA’s Airspace Operations System Project of the Airspace Systems Program.

Melissa M. Mallis, PhD, is a research psychologist and the principal investigator for the Fatigue Countermeasures Group at NASA Ames Research Center, Moffett Field, Calif.

1. Dinges DF. Probing the limits of functional capability: the effects of sleep loss on short-duration tasks. In: Broughton RJ, Ogilvie RD, eds. Sleep, Arousal, and Performance. Boston: Birkhauser; 1992:177-188.
2. Rosekind MR, Co EL, Gregory KB, Miller DL. Crew Factors in Flight Operations XIII: A Survey of Fatigue Factors in Corporate/Executive Aviation Operations. Moffett Field, Calif: NASA Ames Research Center; 2000. Technical Memorandum No. 2000-209610.
3. Co EL, Gregory KB, Johnson JM, Rosekind MR. Crew Factors in Flight Operations XI: A Survey of Fatigue Factors in Regional Airline Operations. Moffett Field, Calif: NASA Ames Research Center; 1999. Technical Memorandum No. 1999-208799.
4. Gander PH, Graeber RC, Connell LJ, Gregory KB. Crew Factors in Flight Operations VIII: Factors Influencing Sleep Timing and Subjective Sleep Quality in Commercial Long-haul Flight Crews. Moffett Field, Calif: NASA Ames Research Center; 1991. Technical Memorandum No. 103852.
5. Dinges DF. The nature of sleepiness: causes, contexts, and consequences. In: Stunkard A, Baum A, eds. Perspectives in Behavioral Medicine: Eating, Sleeping and Sex. Hillsdale, NJ: Lawrence Erlbaum; 1989.
6. Crew factors in flight operations: the initial NASA Ames field studies on fatigue [special issue]. Aviat Space Environ Med. 1998;69(9, section II, suppl).
7. Aircraft Accident Report: Uncontrolled Collision with Terrain, American International Airways Flight 808, Douglas DC-8, N814CK, US Naval Air Station, Guantanamo Bay, Cuba, August 18, 1993. Report No. NTSB/AAR-94/04. Washington, DC: National Transportation Safety Board; 1993. NTIS No. PB94-910406.
8. Dinges DF, Graeber RC, Rosekind MR, Samuel A, Wegmann HM. Principles and Guidelines for Duty and Rest Scheduling in Commercial Aviation. Moffett Field, Calif: NASA Ames Research Center; 1996. Technical Memorandum No. 110404.
9. Rosekind MR, Gander PH, Connell LJ, Co EL. Crew Factors in Flight Operations X: Alertness Management in Flight Operations Education Module. Moffett Field, Calif: NASA Ames Research Center; 2001. Technical Memorandum No. 2001-211385.
10. Rosekind MR, Graeber RC, Dinges DF, et al. Crew Factors in Flight Operations IX: Effects of Planned Cockpit Rest on Crew Performance and Alertness in Long-haul Operations. Moffett Field, CA: NASA Ames Research Center; 1994. Technical Memorandum No. 108839.
11. Neri DF, Oyung RL, Colletti LM, Mallis MM, Tam PY, Dinges DF. Controlled breaks as a fatigue countermeasure on the flight deck. Aviat Space Environ Med. 2002;73:654-664.
12. Oyung RL, Mallis MM. Recovery sleep in flight crew spanning 30 days of flight activity. [abstract supplied] Sleep. In press.
13. Nguyen TT, Colletti LM, Mallis MM. Fatigue factors of concern for current air transport pilots. [abstract supplied] Aviat Space Environ Med. In press.
14. Mallis MM, Dinges DF. Monitoring alertness by eyelid closure. In: Stanton N, Hedge A, Hendrick HW, Brookhuis KA, Salas E. Handbook on Human Factors and Ergonomics Methods. London: Taylor and Francis Publishing Company. In press.
15. Rodriguez DM, Oyung RL, Barger LK, Mallis MM, Jewett ME. Flight deck light exposure of pilots during long-haul trips between the United States and Japan. Sleep. 2002;25:A420.
16. Mallis MM, Mejdal SH. Development of the Astronaut Scheduling Assistant: a biomathematical model to predict alertness and fatigue in astronauts [abstract]. Presented at: Bioastronautics Investigators’ Workshop; January 13-15, 2003; Galveston, Tex.
17. Rosekind MR, Neri DF, Gregory KB, Mallis MM, Bowman SL, Oyung RL. A NASA Education Training Module on alertness management: a survey of implementation and application. Sleep. 2001;24:A415.
18. Rosekind MR, Co EL, Neri DF, Oyung RL, Mallis MM. Crew Factors in Flight Operations XV: Alertness Management in General Aviation Education Module. Moffett Field, Calif: NASA Ames Research Center; 2002. Technical Memorandum No. 2002-211394.
19. Mallis MM, Co EL, Rosekind MR, et al. Evaluation of a web-based fatigue education and training module in the general aviation (GA) population. [abstract supplied] Aviat Space Environ Med. In press.