Flight Time Limitations and Fatigue Risk Management: A comparison of three regulatory approaches

In commercial aviation, crew schedules are regulated by duty time limits, flight time limits, minimum rest rules and other constraints. These rules and limits, collectively referred to as Flight Time Limitations or FTLs, are intended to be a simple method of limiting and accounting for fatigue among flight crew members, as part of overall safety concerns and objectives. Over time, FTLs have evolved, driven by industrial pressures, new scientific data, or to cope with evolving aircraft capabilities. Today, there are major differences among FTLs formulations in different parts of the world affecting crew productivity, crew alertness, and airline competitiveness. With new research on sleep and work-related fatigue it becomes useful to compare existing regulations with new findings. FTLs are relatively straightforward to understand and apply to crew scheduling. Combined with labor agreements and other safeguards, FTLs do a reasonable job of protecting alertness under most circumstances. Unfortunately, FTLs tend to be extremely rigid and limit operational flexibility and efficiency. But, by far the most troublesome aspect of FTLs is the illusion of safety that they create – suggesting that to fly within the limits is inherently safe, while flying outside the limits is inherently unsafe. In recent years, there has been considerable effort spent on increasing our scientific knowledge in the areas of fatigue and alertness. By combining new knowledge of fatigue with safety and risk management processes, the concept of the Fatigue Risk Management System (FRMS) was created. In previous work, we have demonstrated that a properly implemented and managed FRMS should be vastly superior to FTLs in managing alertness [1] while maintaining or improving productivity. Whereas FTLs are not feedback-driven, and often lack a scientific basis, FRMS is by definition intended to be a closed-loop, data-driven process for managing fatigue. In addition to the stronger scientific basis from FRM, there is an added benefit of increased operational flexibility. FRMSs are built around predictive tools including, but not necessarily limited to, mathematical models Flight Time Limitations and Fatigue Risk Management: A comparison of three regulatory approaches