In most cases, the U.S. Department of Transportation (DOT) does not allow airplanes to stay on the tarmac with passengers for longer than three hours. The only situations in which a plane may remain on the tarmac longer than three hours are if the pilot finds a safety reason why the plane cannot deplane its passengers at the terminal, or if air traffic control believes doing so would cause greater flight delays to the overall traffic pattern. While delayed on the tarmac, lavatories must be functional, medical help must be available if needed and passengers must be fed after two hours.
Airlines are not required by law to compensate passengers for delayed flights or even for canceled flights. DOT regulations require compensation only for overbooked flights.
Each airline has its own policy regarding how it treats passengers on delayed flights. Some airlines may provide meals or free phone calls. Some airlines will rebook delayed passengers on later flights or may endorse passengers' tickets to a new airline. The DOT has issued no regulations regarding any of these policies.
