Pair Availability Analysis 
Program Activity Architecture 
phased array antenna 
photon activation analysis 
Policy Approving Authority 
position area for artillery 
primary aircraft authorization 
Pan American Airways 
pancreatic acinar atrophy 
paraazooxyanisole 
Payload Attach Assembly 
Peer Access Approval 
Performance Appraisal Application 
Precipitation Accumulation Algorithm 
Primary Aircraft Authorizations 
Primary Aircraft Authorized 
Primary aromatic amine 
Primary Assigned Aircraft 
Primary Authorized Aircraft 
Prioity Abatement areas 
Priority Area Assessment 
Procurement of Ammunition, Army 
Pad Area Array 
Pan American World Airways 
pancreas-specific antigen 
pantothenic acid 
Paper Agents Association 
Papuan 
Paraazoxyanisole 
partial agonist activity