The Rolex GMT-Master watch was originally designed in collaboration with Pan American Airways and issued by the airline to their crews on long-haul flights. The original GMT Master watch has a 24-hour display fourth hand complicationdirectly linked to and displaying the same time zone as the standard 12-hour hand. This GMT hand enabled the crews to set the watch to GMT or another time zone, and using the rotatable 24-hour scale bezel set to the correct offset a second time zone could be read. GMT or UTC is the time zone that is required for all aviation planning, weather forecasts, schedules and other paperwork.