I thought it was but I wasnt sure

We call it O2
Anyways, I digress.
We are traveling with O2.
Airlines do not allow you to take your own O2 on the plane. You have to hire a Portable Oxygen Concentrator (one that is approved by the airline)
Portable Oxygen Concentrators (POC) work in such a way that they only release O2 on inhale, they dont release O2 on exhale. This is to conserve the battery.
Aiden is only quite young isnt he? Does he use a mask or a nasal cannula? I do not know what POC's are available for masks.
As far as documentation as concerned. You have to have a letter from your Doctor to show the airline approving the use of the POC, you also have to have an acknowledgment form signed by yourself stating that you agree to the rules and regulations set out by the airline.
Here are some links
Oxygen to go
Airline travel with Oxygen
Air travel with Oxygen press release
This is the kind of documentation our airline is going to require of us, just to give an idea
Air Tran Airways Special Needs
If you do feel that you have to travel with O2 you are going to have to contact MAW about it immediately as they will have to arrange it all.
I hope this helps.
Mandy