The FAA has formally proposed new rest period rules for flight attendants. While pilots have been subject to rest period requirements for decades, flight attendants did not fall under the same guidelines. The new rule will require airlines to give flight attendants 10 hours of rest between shifts—Congress first directed the FAA to take action on this matter in 2018. Proponents of the new rule note that flight attendants perform necessary safety and security functions and that fatigue among non-flying personnel is just as dangerous as fatigue among pilots. Airlines for America, a trade group that represents major carriers like United ($UAL@US), Delta ($DAL@US), and American ($AAL@US), says the new rule could cost its members $786 million over the next decade. United stock fell over half a percent on the news while American Airlines stock fell slightly and shares of Delta fell 0.37%.