Southwest has a place on their website when getting your ticket that ask for needed assistance or use of Oxygen, you fill out a form on their site so they can add that to your ticket, I just carry my PC, I don't have to use it so I can just carry it on, the TSA had no problem with it when I showed it to them. I also carry a letter from my doctor that states I have it and may need to use it. They will ask what kind you have and say if approved or not, then I can keep it with me under the seat in front of me. I do take my extra battery too. But I haven't flown now in two years, easier to drive when the trip is around 10 hours, my husband and I leave early morning so we can drive mainly in the day time. Make it fine! But be sure to contact the carrier before you go and check their requirements.

Angie
I fly often with no problem. But I use it 24/7 so I have a simply go mini. They just want to make sure I have enough batteries for the trip.They CK what ever one you have to make sure it's on the OK list.
Here in Idaho I use Norco an outlet that supplies O2 patients. But I have a large concentrator at home for around the house. Many times I fly and call ahead after finding an oxygen supply store at my destination and rent a smaller machine. You will need to specify if you need steady flow or pulse which is what the shoulder carry portables are. I would think you would be happier to get a steady flow machine. I am.
It just takes a little step by step preparation, In the NW Norco will pickup and deliver to an address if you are one of their clients.
Have a wonderful trip!!
Love you Angie!

That test is a Hypoxia Challenge Test and it is offered at many major hospitals. I opted to just not fly anymore.

REgarding taking oxygen onboard to use while flying (aka - battery operated not plugged in). I purchased an Eclipse 5 last summer and had no difficulty taking it onboard with me (I had the doctor letter, paper work from airline/preapproval, yada yada). As of January 1 of this year, I was informed by other Phers that the airlines weren't allowing the double batteries (over 160 watt) onboard. That said, I have a letter from FAA and the manufacturer of the Eclipse showing how it is actually two batteries in the same housing (97.5 ea), and is FAA approved. I'll be making reservations to fly in the next few months and will let you all know how it goes. Angie: it works for me at night as well plugged into the wall - a reason I got that model. Nice and quiet, but I do take an extension cord with me to park it outside the bedroom.

Delta requires registration in advance, but no issues