Acctual Time Of Arrival 
Association of Technical Artists 
Abstracts on Tropical Agriculture 
Academic Travel Abroad 
Advanced Tactical Attack 
Advanced Transit Association 
Aeronautical Telecommunications Agency 
African Technical Association 
Air Transport Agreement 
Alberta Trucking Association 
Aloe Technology Association 
American Teleport Association 
American Teleservices Association 
American Topical Association 
American Transit Association 
American Transport Association 
American Tree Association 
American Tube Association 
Anti-Terrorism Act 
Anti-Terrorism Assistance 
Associate Technical Aide 
Asynchronous Terminal Adapter 
ATtention Answer 
Automotive Technicians Association 
Abort Time Assembly 
Aft Test Article 
Alliance for Taxpayer Access 
Assembly Test Article