According to new research, perceived workload is an independent predictor of fatigue among airline cabin crews — who are responsible for ensuring the safety and comfort of passengers aboard commercial flights.
The study, published in The International Journal of Aerospace Psychology, examined how workload influenced fatigue on ultra-long range flights
“This study forms part of my doctoral research, in which I set out to evaluate Fatigue Risk Management Systems (FRMS) specific to the needs of cabin crew,” said lead author Margo van den Berg, a PhD candidate at Massey University.
“FRMSs are a relatively new approach to managing fatigue risk and airlines are usually required to put a FRMS in place for managing flight crew (i.e. pilots) and cabin crew fatigue on ultra-long range (ULR) flights. These are flights that have a planned flight time longer than 16 hours and thus exceed the maximum limits of traditional flight and duty time regulations.”
“Very long flights can potentially increase the fatigue-related operational risk, especially during the later stages of flight (including the safety-critical landing phase of flight) if they lead to restricted sleep, long periods of wakefulness, and/or high operational demands at sub-optimal times in the circadian body clock cycle,” van den Berg explained.
“In the event of an emergency situation during this time, cabin crew are responsible for managing the cabin and the evacuation of passengers. According to the European Transport Safety Council, 90% of aircraft accidents nowadays are survivable, but fast and efficient evacuation is of vital importance.”
“The main fatigue mitigation strategy on ULR flights is to provide crew with scheduled in-flight rest breaks for sleep in crew rest facilities, but because all cabin crew are required to be awake during meal services, they have less time available for in-flight rest compared to flight crew,” van den Berg said.
“The workload of cabin crew is also quite different in nature compared to that of flight crew. Cabin crews’ work involves a lot more physical tasks and walking and factors such as turbulence, passenger demands, and medical incidents can significantly add to their workload.”
In the study, 55 airline cabin crew wore an actigraph on their wrist and completed a sleep diary during an ultra-long Johannesburg to New York to Johannesburg trip. Before landing, the participants completed a psychomotor performance test and after landing they rated their workload for the entire flight.
“This study showed that workload is an important factor contributing to cabin crew fatigue on ULR flights,” van den Berg told PsyPost.
“On the Johannesburg-New York-Johannesburg ULR trip, when cabin crew rated their workload as higher, they also felt more sleepy and fatigued, and lapsed more often on a psychomotor vigilance task (PVT) at top of descent (the point at which the aircraft transitions from the cruise phase to the safety-critical landing phase of flight).”
“Subjective sleepiness and PVT performance at top of descent were more strongly associated with workload ratings than with how much sleep cabin crew obtained in flight or how long they had been wake,” van den Berg explained.
But the study — like all research — includes some caveats.
“Because this was an observational study, we were not able to establish a cause-and-effect relationship between measures of workload and fatigue. Workload is a multi-dimensional concept resulting from an interaction between task-related aspects (e.g. task difficulty, complexity), person-related aspects (experience, skill level, internal state such as fitness), and temporal aspects (e.g. time pressure, time-on-task),” van den Berg said.
“We therefore chose the NASA Task Load Index, which assesses workload as it is experienced by the individual, thus providing a more valid and practically useful indicator of workload. This subjective measure does however introduce the possibility that fatigue as a supposed effect of workload may in fact become a cause of workload. For example, perceived effort on a task may be greater when someone is feeling more fatigued.”
“Because these findings cannot be generalized to flights that operate with fewer crew, or to shorter flights with less or no opportunity for in-flight rest, we need more studies of this kind to determine to what extent workload influences cabin crew fatigue on these different types of flights,” van den Berg noted.
Of course, several factors besides workload can influence fatigue as well.
“It is important that the effects of workload in flight should not be viewed in isolation, because any flow-on effects of workload can also disturb subsequent sleep, thus contributing to cumulative sleep loss and fatigue across a roster period worked,” van den Berg added.
“Cabin crew often experience fatigue as a consequence of their irregular work schedules, which include early starts, late finishes, night work, frequent time zone changes, and long duty periods, causing sleep loss and circadian rhythm disruption. Considering that their most important role is to ensure cabin and passenger safety during flight, cabin crew fatigue and its associated risks needs to be managed carefully.”
The study, “Perceived Workload Is Associated with Cabin Crew Fatigue on Ultra-Long Range Flights“, was authored by Margo J. van den Berg, T. Leigh Signal, and Philippa H. Gander.