Section 102, The Customs Regu- Citation

The content outward of an aircraft shall be presentedin duplicate in the Form C 6. At the time of presenting his content the master shall produce his journey logbook to the proper officer for stamping together with detailed declarations of the goods loaded made out by the consignors, in the Form C 7. The stamped journey logbook and one copy of the content stamped and signed by the proper officer shall be the clearance and authority for the aircraft to proceed on its journey.