Research examines pilot alertness in multi-leg flights

By Judith Van Dongen, WSU Spokane

cockpitSPOKANE, Wash. – Washington State University and the Regional Airline Association has released a report detailing the findings of the first, science-based study of pilot fatigue in multi-segment flight operations. The study was conducted by researchers at WSU’s Sleep and Performance Research Center.

The study involved a flight simulator experiment that compared alertness in pilots completing duty days with multiple takeoffs and landings versus equal-length duty days that encompass a single takeoff and landing.

The researchers found that the pilots experienced a moderate increase in their level of fatigue in the multi-segment duty days as compared to the single-segment duty days—but their alertness was still high compared to that seen in laboratory studies of night shift work, for example. Furthermore, the modest fatigue on multi-segment duty days did not appear to impact pilots’ flight performance.

“RAA is proud of its sponsorship of this important, independent study intended to fill a void in the science of commercial airline pilot fatigue,” said RAA Interim President Faye Malarkey Black.

Hans Van Dongen

“While the effect on alertness of early-morning and late-night start times has been well documented, prior to our efforts there was no available science on the relative fatiguing effects of operating multiple short-haul flights compared to operating fewer, longer flights,” said Hans Van Dongen, director of the WSU research center and principal investigator on the study.

Twenty-four active-duty commercial airline pilots participated in the study, which was conducted in an aviation training center. The experiment used a full-flight simulator of a Bombardier CRJ-200 regional jet normally flown by the pilots.

Pilots completed a four-day study protocol: they were flown to the training center on day 1, completed two simulated 9-hour duty days on days 2 and 3 and were flown home on day 4. Each pilot completed one duty day with multiple flight segments and another with a single, longer flight segment.

“What made this study special is the balance between the control we had in the flight simulator and all the real-life details we included to make the experiment accurately reflect what a pilot’s duty day looks like,“ said Kimberly Honn, a WSU Ph.D. student who served as an on-site investigator for the study. “This was important as we wanted to keep certain factors—such as takeoff times and weather patterns—constant to optimize the measurement of alertness while making the experiment as realistic as possible.”

She said pilots were instructed to treat the simulator flights as they would regular passenger flights. They arrived in uniform, completed actual checklists and consulted real navigation charts. During their simulated flights, pilots listened to and interacted with air traffic control as they would while flying through the same air space in real life.

During each duty period, pilots completed 10 test bouts consisting of an objective behavioral alertness test and two self-report scales of fatigue. In addition, pilots’ performance on each flight segment was rated using a standard flight evaluation form.

The experiments were overseen by a scientific steering committee that included representation from key stakeholders as well as an independent expert in fatigue in military aviation. The consensus report detailing the study findings is available at

Van Dongen said the study has opened a new field of research to determine the real-world effects of workload on human alertness in around-the-clock, safety-critical environments.

“In any 24/7 industry with long hours, high workload or both, it is vital to establish at what point operators require rest or some other fatigue intervention,” he said. “The aviation industry has been ahead of the game in this area, opening the door for us to start looking more broadly into these issues.”


Hans Van Dongen, WSU Health Sciences Spokane/Sleep and Performance Research Center, 509-358-7755,
Kelly Murphy, Regional Airline Association, 703-967-8113,