2011 study shows air traffic controllers suffer chronic fatigue

WASHINGTON – Air traffic controllers’ work schedules often lead to chronic fatigue, making them less alert and endangering the safety of the national air traffic system, according to a study the government kept secret for years.

Federal Aviation Administration officials posted the study online Monday, hours after the Associated Press reported the findings.

The AP was able to obtain a draft of the final report dated Dec. 1, 2011. The report the FAA posted online was dated December 2012, although the findings appear to be nearly identical to the draft.

The impetus for the study was a recommendation by the National Transportation Safety Board to the FAA and the National Air Traffic Controllers Association to revise controller schedules to provide rest periods that are long enough “to obtain sufficient restorative sleep.”

The study found that nearly 2 in 10 controllers had committed significant errors in the previous year – such as bringing planes too close together – and over half attributed the errors to fatigue. A third of controllers said they perceived fatigue to be a “high” or “extreme” safety risk. More than 6 in 10 controllers indicated that in the previous year they had fallen asleep or experienced a lapse of attention while driving to or from midnight shifts, which typically begin about 10 p.m. and end around 6 a.m.

Overall, controllers whose activity was closely monitored by scientists averaged 5.8 hours of sleep per day over the course of a work week. They averaged only 3.1 hours before midnight shifts and 5.4 hours before early morning shifts.

The most tiring schedules required controllers to work five straight midnight shifts, or to work six days a week several weeks in a row, often with at least one midnight shift per week. The human body’s circadian rhythms make sleeping during daylight hours before a midnight shift especially difficult.

The study is composed of a survey of 3,268 controllers about their work schedules and sleep habits, and a field study that monitored the sleep and the mental alertness of more than 200 controllers at 30 air traffic facilities.

NASA produced the study at the FAA’s request.

Schedules worked by 76 percent of controllers in the field study led to chronic fatigue, creating pressure to fall asleep. “Even with 8 to 10 hours of recovery sleep, alertness may not recover to the full rested baseline level, but may be reset at a lower level of function,” the report said.

“Chronic fatigue may be considered to pose a significant risk to controller alertness, and hence to the safety of the ATC (air traffic control) system,” the study concluded, especially when combined with little stimulation during periods of low air traffic and the human body’s natural pressure to sleep during certain times of the day.

The 270-page study makes 17 recommendations to the FAA, including that the agency discontinue mandatory six-day schedules “as soon as possible.”

FAA spokeswoman Laura Brown said in an email late Monday the agency now requires there be at least two controllers on duty after midnight and that controllers be provided at least nine hours between certain shifts to rest. Controllers are also permitted more time for “recuperative breaks” during shifts, workload permitting.

“Although fatigue is an issue in any 24/7 operation, the FAA has taken many positive steps to minimize fatigue,” Brown said. “The fatigue modeling we’ve done shows that there is greater alertness using these updated scheduling practices.”

NASA researchers completed the study draft several months after a series of incidents involving controllers falling asleep on the job embarrassed FAA officials and led to the resignation of the head of the agency’s air traffic organization. In one incident in 2011, two airliners landed at Washington’s Reagan National Airport late at night without assistance from the airport’s control tower, where the lone controller on duty had fallen asleep.