American Airlines is trying to decrease the time it takes for passengers to board the plane by allowing those traveling with just a personal item to board ahead of other travelers. Passengers who are bringing a personal item that can be placed under the seat are now invited to board after Group 1 passengers and before general boarding groups. Group 1 boarding is offered to elite members, oneworld elite, first class, uniformed military and Priority Access passengers. After Group 1 has boarded, all customers without overhead luggage can board the plane.
Bottom line: American Airlines says the change in the boarding order saves about two minutes per flight. Elite members still receive their priority boarding privileges and the new booking process may encourage more people with rollaboard bags to check their bag at the gate, which will free up some space in the overhead bins. It is free to check a small carry-on bag with overall dimensions less than 45 inches at the gate, however, you will need to go to baggage claim to pick it up.