Keeping Time

The effectiveness of ICAO’s proposed fatigue management initiative depends on its ability to account for workload, says Ashley Nunes.
On a cold March morning in 2011, two airplanes prepared to land at Washington Reagan International Airport, an airport that sits just two miles from the White House. This preparation included obtaining the necessary landing clearance from the tower controller. However, despite repeated attempts, there was no answer from the tower.
The airplanes, a United Airlines Airbus A320 from Chicago, and an American Airlines Boeing 737 from Miami, eventually landed safely within minutes of each other, without the requisite clearance. It was later revealed the controller had fallen asleep, having been at work for a fourth consecutive night shift. An investigation named fatigue as a contributing factor to the incident.
This incident and countless others are used as examples of why fatigue management standards are needed today. The International Civil Aviation Organization (ICAO) has been at the forefront of developing these standards and in 2012, adopted a data-driven methodology to manage fatigue risk. Nancy Graham, Director of ICAO’s Air Navigation Bureau said, “Fatigue Risk Management Systems (FRMS) recognize the growing complexity of crew fatigue and offer multi-layered, comprehensive approaches to various types of fatigue-related hazards.”
Although originally conceived for airlines, FRMS backers emphasize its applicability across all facets of industry. In fact, ICAO recently began applying FRMS to Air Traffic Control (ATC), a move lauded by the International Federation of Air Traffic Controllers Associations (IFATCA). IFATCA’s president, Alexis Braithwaite said, “The move brings much needed attention to an issue the aviation industry has long been aware of, namely controller fatigue.”
Fatigue has been historically viewed as a reduced performance state due to deficiencies in sleep quality, sleep quantity and work scheduling patterns. Efforts to understand fatigue have focused on these ‘circadian factors’ and efforts to manage it have focused largely on changing scheduling patterns across shifts.
However, this focus has come at the expense of consideration of another equally important fatigue-inducing factor, namely workload. In fact, a 2010 MITRE report on controller fatigue found that virtually none of the studies specifically investigating controller fatigue examined workload.
Spiros Rakopoulos, a retired NavCanada controller explains why this is problematic: “The conditions controllers are exposed to while working have just as much impact on our fatigue levels as how much rest we have gotten before and during our shift.” Dubai International Airport’s General Manager of Air Traffic Services, Matthew Riley agrees saying, “Our own experience suggests that controllers can get fatigued as a result of workload and hence, we take precautions to ensure continued safety.”
These can include offering more frequent breaks to controllers during a shift, a commonplace procedure used in Dubai to cope with workload during high traffic periods. Riley says, “Tailoring controller rest periods to traffic demand ensures safety for our customers while demonstrating our commitment to the well being of our controllers.”
More staff can also be added to offset the fatigue associated with managing high traffic. For example, when closely spaced runway operations were implemented in Toronto, an additional tower controller was added to oversee the primary controller. The justification was that working increased traffic levels across multiple runways by a single controller could be extremely fatiguing. Rakopoulos says, “An additional controller provides a second set of eyes and ears to ensure any potential fatigue induced errors do not compromise the safety of the operation.”
Low traffic can also affect safety because maintaining attention when there isn’t much to do can be extremely fatiguing. Eventually, boredom sets in. “We know when people are bored they’re more likely to make performance errors and likely to not be as productive,” says Psychologist John Eastwood, of Toronto’s York University. He adds, “That’s a big deal if you’re an air-traffic controller.”
Eastwood’s ATC analogy is backed up by studies that show controller errors are most likely during low traffic periods. Workload associated with factors other than traffic load can also have an impact on fatigue. For example, on-the job training, where an experienced controller supervises a trainee, requires high levels of concentration that over time can lead to fatigue. Rakopoulos explains that bad weather can be equally problematic because, “ It reduces the margin of error controllers have to play with and therefore you need more concentration that can often result in fatigue.”
Such examples demonstrate that for FRMS to be successful in ATC, it cannot solely offer guidance on work schedule changes across shifts based on circadian factors. Rather, it must also offer direction on how often controllers should rotate through positions during a shift based on workload, a factor that has historically not been considered by FRMS. Dr. Philippe Cabon, a fatigue expert and member of ICAO’s original FRMS taskforce, agrees saying, “Only by accounting for workload and its effects can the full potential of FRMS be realized in ATC.”
Dr. Ashley Nunes is a Principal Scientist at ISA Software, where his research efforts focus on behavioral economics in aviation. Trained in ATC operations, he has lectured across the globe on the challenges facing the air transportation industry. Dr. Nunes earned his Ph.D. in Engineering Psychology from the University of Illinois at Urbana Champaign, where his research focused on the scientific merit of raising controller retirement ages. He can be reached at