A deck deployment system is adapted to facilitate transfer of personnel between spaced elevations. The deck deployment system includes a deck defining a substantially flat and continuous deck surface for supporting personnel. A convertible stairway is hinged to the deck and adapted for movement between a stowed condition and a deployed condition. The convertible stairway includes an adjustable frame assembly and a series of articulating horizontally-disposed foot treads carried by the frame assembly. The foot treads remain substantially horizontal upon movement of the stairway between the stowed condition and the deployed condition. When the stairway is in the stowed condition, the foot treads integrate with the deck to form a substantially flat and continuous portion of the deck surface. When the stairway is in the deployed condition, the foot treads cooperate to form steps extending from the deck to an elevation spaced from the deck surface.