A1's (also known as must rides) are crew members flying to work a flight, they have top priority over passengers because if they are not at the destination another flight will cancel. A1's are never bumped as this could result in a loss of revenue exceeding $60,000.
A3's are also working crew members, but are done with flying. As far as upgrades go, working AA employees will be upgraded; but if the flight is full employees that are flying A3 will be bumped over for a revenue ticket holder.
Unfortunately the only way to get in first class and bump an A1 or A3 employee to coach is to buy a first class ticket.
[This message has been edited by Dalguy (edited 11-29-2000).]