I know I have touched on this in various ways, but more specifically flights... Travel via plane is not out of the picture for most. There are people on OT who routinely go to Europe or the Islands and are on Oxygen Therapy. It is just a matter of understanding a few things.
1. The airline's rules and requirements. Each airline has different requirements, and each airline has a department for just this, where some will actually offer Oxygen for the flight (so you don't have to worry about battery life) if you notify them soon enough - in fact make it ASAP when you book the tickets- the sooner the better. However, if that is not an option, PLEASE know that battery life reduces once at altitude therefore you will have to factor battery life. It can reduce up to 10% once leveled off. Thus, if the airline says (for example) you need to have double the flight time in battery life, and it is close... plan for 1 extra battery pack!
2. Factoring time at the airport can be hard. And for some of that you may be able to plug the concentrator in while sitting at the gate, but also consider the time it takes to get to the gate from the car - through check in even if you have a ride or a wheelchair and get expedited. Also, time while waiting for baggage, car rental, customs, getting situated at the hotel or location, etc.
3. Test battery life BEFORE your maiden voyage. Some vendors claim battery life, but some have them wrong simply by mistake (what we learned). We discovered for the particular battery for my mom's unit was advertised as 5 hours (for her O2 usage/need). Turns out it was a mistake on the site, and it was really 2.5 hours. Luckily, the airline was going to let her use their oxygen in flight but that was a startling discovery. Also as stated in point #1, know that batteries automatically lose life once up at altitude. You will need to factor for a little more. So with that said, check it out prior to flying and factor fore extra!
4. Have fun! Let the airport give you the ride... save the energy for fun at your destination.
Now if you are so new to this that you need help with understanding battery operated concentrators, or are a caregiver and trying to get up to speed, please reach out. Whatever place your are in, let me know and I can help walk you through different suppliers and how to connect with airlines and what questions to ask.
Buses and trains are somewhat similar, but again each have their requirements!