DISNEYWORLDBORN2SHOP,
I, too, travel in an electric wheelchair and have a few answers for you. The airlines cannot, by law, charge you any additional fees to carry your MIL's electric wheelchair. Doing so would violate the ADA laws that apply. You should call the airline as soon as you have purchased the tickets and talk to someone in their special needs department. The airlines all do things a bit differently, but you should always let them know ahead of time what you'll need, and what you'll be bringing with you. As soon as you have flight info, be sure to let
DCL know so that they can provide wheelchair accessible transportation.
Here are some tips to help the situation go a bit easier:
At the Gate:
Inform the gate agent of your needs, and provide him/her with a copy of instructions for your MIL's wheelchair. Write or type these instructions out and provide at two copies for each leg of your trip. Give one copy to the ticket agent, and one to the gate agent. Include in these instructions what flight(s) youll be on, your confirmation number, if your chair has a wet-cell or a dry-cell battery (generally marked on the battery pack of the chair...), how to recline your chair (if applicable), if it is okay to stow your chair in a different position than upright (some chairs wont fit upright through the baggage door on the plane), whether the chair is collapsible, and any other info you think the airline might be able to use.
Most airlines provide pre-boarding privileges, although they will seldom announce that they do. Request that you would like to preboard. It will make boarding the plane less stressful as they help you get seated before loading the other passengers.
Ask the agent whether or not your MIL's wheelchair will be gate-checked. This is VERY IMPORTANT. Some airlines do not gate-check electric wheelchairs. This means that your chair will show up through a special baggage delivery point near where the regular baggage arrives. If they will gate-check your MIL's chair, wait until everyone else has gotten off the plane, and that will give them enough time to transport the wheelchair up from baggage to the jet-way where it will be waiting for you.
All in all, most airlines are very good about helping those of us on wheels. Have a great trip, and let me know if you have any more questions!