The term “employment” shall not include service performed as an officer or member of a crew on or in connection with a vessel which is not an American vessel; and service performed as an officer or member of a crew of an American vessel on or in connection with such vessel, if the operating office, from which the operations of the vessel operating on navigable waters within or within and without the United States are ordinarily and regularly supervised, managed, directed and controlled, is without this State. The term “American vessel” means any vessel documented or numbered under the laws of the United States; and includes any vessel which is neither documented or numbered under the laws of the United States nor documented under the laws of any foreign country, if its crew is employed solely by one or more citizens or residents of the United States or corporations organized under the laws of the United States or of any State.
     B. The term “employment” shall not include service performed by an individual on or in connection with an aircraft which is not an American aircraft, if the individual is employed on or in connection with such aircraft when outside the United States. The term “American aircraft” means an aircraft registered under the laws of the United States.