When the cabin crew has finished serving the meal, the flight attendants finally have time to take a break. But what about the pilot? During take off and initial climb they are fully occupied with flying the aircraft has reached cruising altitude, a relatively quiet phase begins for the pilots. A viation authorities stipulate that pilots must take short rest periods on flights lasting more than twelve hours. To enable them to do so, a third pilot, Senior First officer with a special license, must be on board. He replaces the captain and so-pilot, alternately. This ensures that the cockpit is always manned by two well-rested pilots, who can then concentrate their attention on the descent and landing.