Handicapped adult travelling by plane

Does anyone know if airplanes have handicapped bathrooms? (I don't think so).
Can anyone offer any information about a handicapped person travelling by plane?
TIA

I have participated in a board (while planning our travel last summer) that has lots of people with a huge amount of knowledge about flights, planes and many people in wheelchairs who fly on a regular basis. They can tell you what resources there are, what you need to know and what type of bathrooms to expect on different types of airplanes.

I am pretty sure it is against forum rules for me to post the link though, so PM me if you think it would be helpful.
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Liba, mommy to Zlata Tova 5/6/98, Tziporah Faiga 1/12/01, Esther Rivka 7/13/04 and Avraham Chaim 7/2/2006

At the boarding gate, handicapped passengers should be able to use specialised wheelchair to get to their seat (it's a narrower one that fits to aisle width). So you can call the flight attendants to get that wheelchair (it's foldable and stored somewhere else on the plane). Though you can't wheel all the way in, he/she may need some help opening the door and seating on the toilet seat. (Check with airlines if there's railing).
Also procedure may differ by the types of aircrafts. Above is for wide body, not single-aisle or smaller planes.