The 3 hour rule for airlines is a rule that refers to the U.S. Department of Transportation regulations.
The 3 hour rule for airlines requires that airlines must give passengers on domestic flights the option to deplane after 3 hours of being on the tarmac.
And for international flights it goes up to 4 hours and so airlines must give passengers on international flights the option to deplane after 4 hours on the tarmac.
The 3 hour rule for airlines has exceptions though for safety, security or if air traffic control advises that returning to the gate would disrupt airport operations.
And during the delay, airlines must also provide passengers with water and food, working lavatories and medical assistance if needed.
For domestic flights, airlines must provide passengers with the option to get off the plane after 3 hours of being on the tarmac.
For international flights, airlines must provide passengers with the option to get off the plane after 4 hours on the tarmac.
But the 3 hour rule for airlines does apply if the pilot in command determines that allowing a passenger or passengers off the plane would jeopardize security or safety.
Or if the air traffic control advises the pilot that returning to the gate would significantly disrupt airport operations.
Or if there is a safety or security reason that prevents the aircraft from moving to deplane passengers.
Airlines must provide passengers with adequate food and drinking water within 2 hours of the delay, lavatories must also remain operable and medical attention and medical assistance must also be provided if necessary.