(a) REGISTRATION REQUIREMENT.-Except as provided in subsection (b) of this section, a person may operate an aircraft only when the aircraft is registered under section 44103 of this title.
(b) EXCEPTIONS.-A person may operate an aircraft in the United States that is not registered-
(1) when authorized under section 40103(d) or 41703 of this title;
(2) when it is an aircraft of the national defense forces of the United States and is identified in a way satisfactory to the Administrator of the Federal Aviation Administration; and
(3) for a reasonable period of time after a transfer of ownership, under regulations prescribed by the Administrator.