It's called Federal Aviation Regulation, Part 117, an entire section of the rules regulating aviation devoted entirely to airline pilot rest requirements.
The rules went into effect last Saturday, January 4, right in the middle of some of the worst winter weather in decades. Experts agree the combination of bad weather and the new rest rules contributed to a higher number of flight delays and cancellations than usual for such an event.
I talked about the new rest rules with Dan Silbaugh, the recording secretary of International Brotherhood of Teamsters Local 357, which represents the pilots of Indianapolis-based Republic Airways Holdings. If you've flown much in the eastern two-thirds of the U.S., chances are you've been on a Republic aircraft.
Silbaugh says it will be at least a year before the full impact of the new rest regulations is known. However, he predicts that the next two or three months could see major disruptions in air travel as airlines fine tune their staffing and scheduling to comply with the new regulations.