Pilot Fatigue


Airlines aim to reduce unit costs by using more planes and workers as air traffic has expanded. Pilots and crew now have longer workweeks and greater workloads as a result of this. As a result, a pattern of increased accident likelihood can be seen. In both civil and military aviation, fatigue has consistently been a significant risk factor for aircraft mishaps and accidents. The amount of fatigue-related safety accidents has increased, and crews now attribute operational errors like landing on the wrong runway or misreading fuel to stress and lack of sleep.1 It has been determined to be the probable cause of 21-23% of major aviation accident investigations during the past two decades.2 In 2020, the European Aviation Safety Agency (EASA) identified “the state of well-being and fitness for duties” as the top safety issue for large aeroplanes.3

As per the International Civil Aviation Organisation (ICAO),

A physiological state of reduced mental or physical performance capability resulting from sleep loss, extended wakefulness, circadian phase, and/or workload (mental and/or physical activity) that can impair a person’s alertness and ability to perform safety-related operational duties.4

This definition emphasises that fatigue is a multifaceted issue with a range of causes and manifestations, including decreased performance and diminished awareness, which may make it more difficult for a person to carry out their job safely. It does not attempt to distinguish between physical and mental tiredness.5

Accidents caused by fatigue in India and abroad

The horrific Air India Express Flight 812 tragedy in 2010 is an illustration of how fatigue has a significant impact on the safe operation of aeroplanes. 158 people were killed when the 166-person aircraft that was carrying them crashed upon landing in Mangalore. In fact, the captain’s snoring was recorded for the first time ever by the cockpit voice recorder. As contributing factors to the collision, residual tiredness and poor judgment were mentioned.6 Not only has fatigue been identified as the key factor in numerous aircraft mishaps in India, but this incidence is not an isolated one. These include the Bell 407 helicopter crash in Gund, J&K, in 2012, the Indian Airlines Caravelle tragedy in Mumbai, India, in 1976, which claimed the lives of 95 people, and the Jet Airways plane that ran off the runway in 2017 while carrying 161 passengers.7

According to the National Transportation Safety Board (NTSB) of USA and the Libyan Civil Aviation Authority, fatigue has also been linked to a number of previous serious aircraft accidents.8 Since 1972, the NTSB has issued nearly 200 safety recommendations pertaining to fatigue, recognising its importance in aviation safety.9 Accidents caused by fatigue have not significantly diminished despite these efforts. Fatigue was found to be a contributing factor in 23% of significant aircraft accidents between 2001 and 2012, up from 21% in a 1980 study.10

Fatigue-related mishaps also have an enormous effect on military aviation. According to reports, fatigue played a role in 25% of the Class A incidents involving night tactical fighters in the US Air Force (USAF) and 12% of the US Navy’s most serious mishaps.11 An analysis of USAF mishap data from the past 15 years found that almost 4% of all accidents involved fatigue, costing more than $2 billion and leaving 32 people dead. Notably, a higher number of Class A accidents (24%) were related to fatigue, which is comparable to the rate seen in accidents involving civil aircraft.12 This variation may result from a more complete examination of human variables in serious accidents.

Cause and effect of fatigue and its contributing factors in Aviation

Causes and effects

Aviation fatigue originates from a myriad of factors, including sleep deprivation, prolonged wakefulness, circadian rhythm disruptions, and the workload’s demands. Lack of sleep or poor sleep quality can severely hamper a pilot’s performance and attention span.13 Pilots are encouraged to sleep 7-8 hours per night to maintain optimum performance. Staying awake for extended periods increases the propensity for sleepiness, affecting performance, especially for pilots who have been awake for extended periods.14 Circadian rhythm disturbances due to night shifts or time zone changes can augment fatigue, impacting the pilot’s alertness and performance, especially during the window of circadian low and post-lunch dip.15 The workload can induce fatigue in two ways: overwhelming demands lead to fatigue in high-workload situations, while low-workload situations might reveal latent sleepiness due to insufficient stimulation.16

Fatigue can significantly impact pilots, leading to impaired attention, sleepiness, and short bouts of sleep during flights, which could compromise the pilot’s responsiveness and attentiveness. Cognitive functions such as executive functions, sustained attention, and memory are compromised due to decreased performance, leading to increased errors, and diminished situational awareness.17 Fatigue can also lead to long-term health issues, including decreased productivity, depression, anxiety, cardiovascular strain, and conditions such as obesity, diabetes, hypertension, and certain cancers. Recognising and alleviating fatigue is crucial for aviation safety and pilots’ well-being. Adequate rest, strategic scheduling, and promoting conducive sleep environments are essential in fighting fatigue in aviation.18

Its contributing factors in the aviation industry

The aviation industry factors contributing to fatigue include operation type, international flights, planning aspects, the number of flight segments, and individual differences among pilots. It was initially believed that short-haul flights caused more fatigue than long-haul flights.19 However, recent studies suggest short-haul pilots experience more fatigue, possibly due to an increase in short-haul flights, leading to longer duty periods and increased workload. Jet lag and circadian rhythm disturbances are prevalent in international flights, especially when crossing time zones, leading to difficulties in adjusting to local time zones and increasing fatigue during return flights.20 Work organisation, rostered duty patterns, and crew composition significantly contribute to fatigue. The length of duty, including flight time and administrative tasks, is a significant fatigue predictor, with early start times and late-night duty periods also impacting pilots’ sleep and performance.21 Operating multiple flight segments during a duty period can cause higher fatigue levels, likely due to the increased workload from more take-offs and landings.22 There are significant variations in how pilots experience and cope with fatigue, with factors such as age, circadian type, work-life balance, physical activity, and relationships influencing fatigue occurrence among pilots. Addressing these factors is crucial to reducing pilot fatigue and ensuring aviation safety, requiring appropriate scheduling, rest opportunities, and fatigue mitigation strategies.

Preventive steps

In-flight countermeasures, which may be roughly categorised into non-pharmacological and pharmacological tactics, are essential for controlling pilot tiredness. Cockpit napping, which is approved by airlines like Air Canada and British Airways enables pilots to alternately take naps during flight segments, particularly long-haul ones, is one non-pharmacological countermeasure. On long and ultra long-haul flights, bunk sleeping is made possible, providing crew members with rest areas whose layout and comfort might affect the quality of their sleep. Mild physical exercise, posture modifications, and social connection during activity breaks might break up monotony and increase attentiveness. Usually, shorter, more frequent breaks work best. Even when one is sleep deprived, cockpit light, especially short wavelength lights, might increase performance and alertness. Flight crew rostering may accommodate regular pauses for rest, manage the effects of prolonged wakefulness and fatigue, and maintain flight safety throughout crucial stages. It is important to time meals and sleep well, get as much morning sunshine as possible, and get as little evening light as possible while adjusting to different time zones or work schedules. In addition to maintaining good sleep habits, regular sleep patterns, a bedtime routine, pleasant sleeping conditions, and avoiding coffee before night, prophylactic napping, which is practised before anticipated sleep loss, can increase performance.

The pharmacological approach involves hypnotics or sleep medications in contexts where obtaining sufficient sleep is difficult due to excitement, anxiety, jet lag, work shifts, or environmental factors. Hypnotics like temazepam, zolpidem, and zaleplon may promote sleep quality in limited circumstances based on required sleep timing and duration. However, their usage necessitates careful consideration due to associated risks and benefits.

In conclusion, a combination of non-pharmacological and pharmacological approaches can effectively combat pilot fatigue, enhance alertness, and promote flight safety. Implementing these strategies along with proper scheduling and rest opportunities is vital for managing fatigue in aviation operations.23

Fatigue risk management system

International Civil Aviation Organisation (ICAO’s) fatigue risk management system (FRMS)24 is a comprehensive approach designed to address the risks associated with fatigue in the aviation industry. Airlines and other aviation operators use it to protect flight crew members’ safety and well-being and reduce the possibility that fatigue may have a detrimental impact on operational performance.

Individual variances in circadian cycles and tiredness tolerance are taken into consideration in FRMS, which is based on scientific study and data analysis. It tries to recognise and reduce fatigue-related dangers using proactive methods as opposed to reactive ones.

The key components of ICAO’s FRMS can be summarised as follows:

  1. Fatigue risk assessment: Airlines conduct regular assessments to identify potential fatigue risks within their operations. This involves analysing crew schedules, duty times, and rest periods using scientifically validated models and tools.

  2. Fatigue risk mitigation: Based on the assessment, operators implement a range of strategies to reduce the likelihood of fatigue-related issues. These may include optimised duty rosters, controlled duty hours, and improved scheduling practices to ensure sufficient rest periods between flights.

  3. Fatigue education and training: Training programs are provided to flight crew members and management personnel to raise awareness of fatigue-related issues and equip them with knowledge and skills to identify and manage fatigue risks effectively.

  4. Fatigue reporting and management: A robust reporting system is in place to encourage flight crew members to report fatigue-related concerns without fear of reprisals. The data collected from such reports are used to continuously improve the FRMS.

  5. Fatigue monitoring: Airlines employ various methods to monitor crew fatigue, including fatigue surveys, biomathematical models, and fatigue-related data analysis. This allows them to detect emerging trends and make necessary adjustments to their FRMS.

  6. Continuous improvement: ICAO’s FRMS emphasises a continuous improvement approach. The system is regularly reviewed and refined based on the latest scientific research and industry best practices.

ICAO’s FRMS reflects a collaborative effort between regulators, airlines, and crew members to manage and mitigate the risks associated with fatigue effectively.

Policy suggestions from Indian perspective

A non-profit organisation called Safety Matters Foundation conducted a study on Indian pilots flying domestically and regionally within four hours of flight time, and the results showed that many pilots working for Indian airlines had “daytime sleepiness” as a result of extreme exhaustion. 66% of the 542 pilots who took part in the study admitted to dozing off during their shifts in the cockpit. The survey’s findings highlighted many significant points:

(i) 66% of pilots acknowledged falling asleep in the air without waking up the rest of the crew.

(ii) 54.2% of the pilots reported being severely excessively sleepy during the day.

(iii) Morning departures were cited as the primary source of fatigue by 74% of pilots.

(iv) 31% reported experiencing a close call due to fatigue-related problems while flying.

The survey findings also indicated that around 54% of pilots suffered from severe excessive daytime sleepiness, while 41% experienced moderate daytime sleepiness.25

Aircraft accidents have been linked to fatigue as a major contributing factor, exposing the ineffective coping skills of pilots under strain. Pilot duty hours have grown as a result of airlines’ efforts to run with fewer employees, adding to their stress and fatigue. It is essential to increase corporate support for putting safety procedures into place and keeping them up to date in order to address these alarming results and advance a safety culture in the aviation sector. Airlines should be required to use Fatigue Risk Management Systems (FRMS), and the Directorate General of Civil Aviation (DGCA) should provide precise guidelines for doing so. The present regulations, in the opinion of Captain Amit Singh, head of the Safety Matters Foundation, are prescriptive and controversial, without a strong scientific basis for flying and duty time regulations. It is essential to revise these regulations based on more reliable scientific principles.26

Aviation experts emphasise the importance of adhering to international norms regarding fatigue risk management. The International Civil Aviation Organisation has introduced amendments to “Operation of Aircraft” guidelines, recommending the implementation of more scientific Flight Duty Time Limitations (FDTL) by airlines globally. The International Air Transport Association (IATA) has also endorsed these guidelines.27

To enhance safety and mitigate fatigue-related risks, Indian airlines should prioritise the well-being of their pilots by implementing robust FRMS practices and adhering to scientifically backed FDTL regulations. A proactive approach towards fatigue management is crucial in ensuring the safety and reliability of Indian aviation operations.


India is one of the countries where fatigue is a major factor in aviation accidents, and the frequency of fatigue-related occurrences among pilots highlights the need for preventative measures and regulatory changes to ensure aviation safety. The tragic accident of Air India Express Flight 812 and other comparable occurrences underscore the potentially lethal effects of pilot fatigue and the necessity for airlines and regulators to take proactive measures to address it. Aviation fatigue has a variety of causes and symptoms, including sleep deprivation, prolonged wakefulness, circadian rhythm disturbances, and workload. All of these factors must be identified and mitigated to keep pilots aware and performing well. An efficient method to systematically detect and manage hazards associated to tiredness is to use the suggested tiredness risk management system of the International Civil Aviation Organisation. The DGCA should require Indian airlines to implement FRMS, including rules for flight and duty time based on science. To properly manage aviation tiredness, airlines, authorities, and pilot organisations must work together. Promoting best practises, following international regulations, and placing a high priority on crew well-being will greatly improve safety in the Indian aviation industry and reduce accidents brought on by tiredness.

†Third year student, BA LLB (Hons.), Maharashtra National Law University, Mumbai. Author can be reached at agrani.bhati@mnlumumbai.edu.in.

††Third year student, BA LLB (Hons.), Maharashtra National Law University, Mumbai. Author can be reached at aditya.singh@mnlumumbai.edu.in.

1. Marina Efthymiou, Sinead Whiston, John F. O’Connell, Gavin D. Brown, “Flight Crew Evaluation of the Flight Time Limitations Regulation”, (2021) 9(1) Case Studies on Transport Policy 280-290.

2. J.A. Caldwell, “Crew Schedules, Sleep Deprivation, and Aviation Performance”, (2012) 21(2) Current Directions in Psychological Science, 85-89.

3. European Union Aviation Safety Agency (EASA), Annual Safety Review (Cologne, Germany, 2020).

4. International Civil Aviation Organisation (ICAO), Manual for the Oversight of Fatigue Management Approaches, Doc. 9966 (Montréal, Canada, 2020).

5. Q. Yara Wingelaar-Jagt., Thijs T. Wingelaar, , Wim J. Riedel, & Johannes G. Ramaekers, Fatigue in Aviation: Safety Risks, Preventive Strategies and Pharmacological Interventions”, (2021) 12 Frontiers in Physiology.

6. Report of the Court of Inquiry on Accident to Air India Express Boing 737-800 Aircraft VT-AXV on 22nd May, 2010 at Mangalore (2010), < https://reports.aviation-safety.net/2010/20100522-0_B738_VT-AXV.pdf>. [Government of India, Ministry of Civil Aviation].

7. Abhijeet Anand, “DGCA Forms Committee to Review Guidelines on Rest Period Given to Pilots”, (thestatesman.com, 10-1-2018).

8. National Transportation Safety Board, Controlled Flight into Terrain Korean Air Flight 801 Boeing 747-300, HL7468, Nimitz Hill, Guam, 6-8-1997, (Washington, DC, USA, 2000)), Libyan Civil Aviation Authority, Final Report of Afriqiyah Airways Aircraft Airbus A330-202, 5A-ONG Crash Occurred at Tripoli (LIBYA) on 12/05/2010 (2013).

9. Jeffrey H. Marcus, Mark R. Rosekind, “Fatigue in Transportation: NTSB Investigations and Safety Recommendations”, (2017) 23(4) Injury Prevention 232-238.

10. E. Gene Lyman, Harry W. Orlady, Fatigue and Associated Performance Decrements in Air Transport Operations, Center N.A.R. (Battelle Columbus Laboratories, 1981).

11. C.S. Ramsey, S., S.E. McGlohn, “Zolpidem as a Fatigue Countermeasure”, (1997) 68(10) Aviation, Space and Environmental Medicine 926-931.

12. Alex R. Gaines, R., Megan B. Morris, B., Glenn Gunzelmann, “Fatigue-Related Aviation Mishaps”, (2020) 91(5) Aerospace Medicine and Human Performance 440-447.

13. D. Arthur Drury, Sally A. Ferguson, Matthew J.W Thomas, “Restricted Sleep and Negative Affective States in Commercial Pilots During Short Haul Operations”, (2012) 45 Accident Analysis & Prevention 80-84.

14. Max Hirshkowitz, Kaitlyn Whiton, Steven M. Albert, Cathy Alessi, Oliviero Bruni, Lydia DonCarlos, et al., “National Sleep Foundation’s Updated Sleep Duration Recommendations: Final Report”, (2015) 1(4) Sleep Health 233-243.

15. National Transportation Safety Board, “Safety Study: A Review of Flight Crew-Involved, Major Accidents of US Air Carriers, 1978 Through 1990” (Washington, DC, 1994).

16. International Air Transport Association (IATA), International Civil Aviation Organisation (ICAO) and International Federation of Air Line Pilots’ Associations (IFALPA), Fatigue Management Guide for Airline Operators (Montréal, Canada, 2015).

17. International Civil Aviation Organisation (ICAO), Manual for the Oversight of Fatigue Management Approaches, Doc. 9966 (Montréal, Canada, 2020).

18. International Civil Aviation Organisation (ICAO), Manual for the Oversight of Fatigue Management Approaches, Doc. 9966 (Montréal, Canada, 2020).

19. Samira Bourgeois-Bougrine, Philippe Carbon, Charlotte Gounelle, Regis Mollard, Alex Coblentz, “Perceived Fatigue for Short and Long-Haul Flights: A Survey of 739 Airline Pilots”, (2003) 74(10) Aviation, Space and Environmental Medicine 1072-1077.

20. Philippa Gander, Hannah M. Mulrine, Margo J. van den Berg, Lora Wu Alexander Smith, Leigh Signal, Jim Mangie, et al., “Does the Circadian Clock Drift When Pilots Fly Multiple Transpacific Flights with 1 to 2 Day Layovers”, (2016) 33(8) Chronobiology International 982-994.

21. International Civil Aviation Organisation (ICAO), Manual for the Oversight of Fatigue Management Approaches, Doc. 9966 (Montréal, Canada, 2020).

22. International Civil Aviation Organisation (ICAO), Manual for the Oversight of Fatigue Management Approaches, Doc. 9966 (Montréal, Canada, 2020).

23. Rajee Olaganathan, Timothy B. Holt, Jackie Luedtke and Brent D. Bowen, “Fatigue and its Management in the Aviation Industry, with Special Reference to Pilots”, (2021) 10(1) Journal of Aviation Technology and Engineering 45-57.

24. International Civil Aviation Organisation (ICAO), Manual for the Oversight of Fatigue Management Approaches, Doc. 9966 (Montréal, Canada, 2020).

25. Disha Shah, “Majority of Indian Pilots Doze Off in Cockpits due to Fatigue, Survey Claims”, (wion.com, 23-9-2022).

26. Disha Shah, “Majority of Indian Pilots Doze Off in Cockpits due to Fatigue, Survey Claims”, (wion.com, 23-9-2022).

27. Abhijeet Anand, “DGCA Forms Committee to Review Guidelines on Rest Period Given to Pilots”, (thestatesman.com, 10-1-2018).

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