There will be no problem boarding her. Notify the airline that your mother cannot stand or walk and that she will need an aisle chair to board.

At the gate, your mother will be given a gate check tag for her wheelchair. She will be pre-boarded. She will be able to remain in her own wheelchair to traverse the jetway.

At the door of the plane, she will be met by two workers with an aisle chair, which is a narrow chair that fits in the airplane aisle. Since she can stand to do a pivot transfer, there should be no major issues in her transfer from her own chair to the aisle chair. The aisle chair has three straps, 2 criss-crossing from shoulder to hip and one around the legs. Make sure all straps are fastened snugly.

Her own wheelchair will be taken down to the hold with the strollers and gatechecked luggage. Be sure to remove all removable bits (I take my cushion with me). If it's a power chair there are additional considerations that I won't go into in this post.

The workers will take her to her seat and will assist with her transfer if desired. They are usually not trained in safe transfers so your mother will need to give them the appropriate direction. Keep in mind that it is harder to transfer into first class seats because of the large, immovable armrest - she will probably either have to do a standing pivot transfer or be lifted. If in economy, she will be assigned a seat with a movable armrest and can do a sliding transfer.

Since she's got a catheter and has someone with her, restroom access won't be a problem during the flight. Shortly before landing, it's generally a good idea to ring the flight attendent and remind him/her that a) she requires an aisle chair to deplane, and b) she has her own wheelchair that she expects to receive at planeside.

At landing, she will wait until all other passengers have deplaned. The aisle chair will be brought to her seat and the process proceeds in reverse.

Here are some additional resources on flying with a wheelchair:

http://www.spinal-injury.net/disabled-flying-guide.htm
http://www.flying-with-disability.or...lity_aids.html
http://www.gimponthego.com/tips1.htm

Here are the TSA pages about people with mobility disabilities and mobility aids:
http://www.tsa.gov/travelers/airtrav...rial_1371.shtm
http://www.tsa.gov/travelers/airtrav...rial_1370.shtm

I can't give you any specific AA information, but all the mainline carriers are dealing fairly well with wheelchair passengers. The applicable regulation for airlines is not the Americans with Disabilities Act, but the Air Carrier Access Act - you can read it or summaries of it in order to familiarize yourself with the rights of disabled air passengers.

I hope this helps, and that your parents have an excellent trip!