A.I.D.
Agency for International Development.

A.T.A.
American Trucking Association.

AA
Always Afloat (In some ports the ship aground when approaching, or at berth.)

AAR
Abbreviation for:1- Against All Risks (insurance clause). 2-Association of American Railroads

ABI
U.S. Customs' "Automated Broker Interface," by which brokers file importers' entries electronically.