The Department of Transportation today announced a new rule that prohibits U.S. airlines operating domestic flights from allowing aircraft to remain on the tarmac for more than three hours without deplaning the passengers. The rule notes exceptions for safety or security, or if air traffic control advises the pilot in command that returning to the terminal would disrupt airport operations. "Airline passengers have rights, and these new rules will require airlines to live up to their obligation to treat their customers fairly," transportation secretary Ray LaHood said in a statement. U.S. carriers operating international flights departing from or arriving in the United States must specify, in advance, their own time limits for deplaning passengers, with the same exceptions applicable. Carriers now are required to provide adequate food and potable drinking water for passengers within two hours of the aircraft being delayed on the tarmac; to maintain operable lavatories, and, if necessary, provide medical attention. Read the DOT's full statement here. The Air Transport Association of America, the industry trade organization for U.S. airlines, is not happy with the new regulation. "We will comply with the new rule even though we believe it will lead to unintended consequences -- more cancelled flights and greater passenger inconvenience. In particular, the requirement of having planes return to the gates within a three-hour window or face significant fines is inconsistent with our goal of completing as many flights as possible. Lengthy tarmac delays benefit no one," said ATA president and CEO James C. May. The National Business Travel Association and the Business Travel Coalition applauded the DOT's move.