Before engaging in transportation operations, or at such time as the board deems appropriate and necessary, the board shall appoint a general manager who shall be the chief executive and operating officer of the authority. The general manager shall have management of the properties and business of the authority and the employees thereof. He shall direct the enforcement of all resolutions, rules and regulations of the board, and shall enter into contracts as necessary under the general control of the board. The general manager shall serve at the pleasure of the board.