Bill has been using the Inogen unit since he was about 76. He's 84 now. We did have one malfunction with it this last trip. But it was old and ready to be replaced. I believe the new Inogen 5s come with a 3 year warranty. I found Alpa Medical on facebook so you could message them your questions/ They did tell me that if a new machine was ordered it would take 3 weeks to arrive. that makes sense. We were in Puerto Vallarta when we we had trouble this last time and could find no one to ship a replacement. I will find out more for the next time in PVR! If you don't mind my asking, how many liters does your wife use? Planes fly at 36000 feet. My husband needs to put it on a 4 or 5 for that elevation. That also means batteries don't last as long. We were able to charge one at the seat, because Bill had an extra cable to do so. You might want to go to your local medical supply place once you purchase your unit and talk to them about batteries, cables, etc. Before we went to the Inogen 5 he used and Inogen 3. It too was a good unit, but it only went to 5 liters. The batteries are expensive, but a small price to pay. Your doctor will tell you how many liters of oxygen your wife needs. My husband is on oxygen 24/7. We have a big machine at home that he can walk all over the house with (lots of cable) and then his portable. Good luck to you. We are still planning on going to SXM at the end of June!