I've done this a ton with my kids, and it's pretty simple. I think the ages are 6-14; 15-17 can travel as UM, but it isn't required in order for them to travel alone. Also, I think it is direct, domestic flights only. You'd have to check to be 100% sure on the above, but I can tell you for sure that the fees are waived.

The biggest thing to remember is that you should CALL THE TRAVEL CENTER WITH THE LISTING PNR AFTER YOU LIST FOR THE FLIGHT. They will mark the flight as UM travel, and take down names, phone numbers, addresses, and relation of those dropping off and picking up your child. For some reason, there is no way to do this on EmployeeRes. If you don't call it in, the ticketing agent has to do it when you check-in. Many of the agents don't know how to do it in their system and it can take a long time to track someone down and get it all ironed out. Seriously. A LOOOOOOONG time. I only point this out, because occasionally, the wait times are super long when calling in, and you'll eventually be tempted to just hang up and take care of it at the airport. And that will of course be the day you miss your flight because the ticketing agent has no idea how to change your listing on the computer.

You can't complete your check-in at a kiosk, because an agent needs to print out special paperwork that stays with your child while they travel, and give them an armband that distinguishes them as a UM. The paperwork (packet) is always in the possession of the adult presently responsible for the child. It eventually is opened at the destination airport, where the ID of the adult picking up is verified against the information in the packet. (You know, the information you provided when you CALLED THE TRAVEL CENTER.) They will also print you (or the adult dropping off) a pass to take the child through security. You stay with the child at the gate until they are cleared to board with an assigned seat. The gate agent takes your child (and the packet) down the jetway, where the FA assumes stewardship of the child.

You are supposed to stay in the boarding area until the flight is off the ground in case of a return to gate, etc., although very rarely do gate agents actually stick around to be sure, so you're on the honors system with that. I usually use the United app or flightaware to make sure the flight has taken off before leaving the airport. After that, I personally like to track the flight progress using the same means just to make sure I'm in the loop if there's an in-flight diversion or anything of that nature.

As far as picking up, make sure the adult on the other end arrives with enough time to wait in a check-in line, get their security document printed, wait in a TSA line, clear security, and be at the gate before the flight arrives. Again, their ID is verified against the info you provided when you CALLED THE TRAVEL CENTER, and the kid is now in their custody.

I've done this a bunch of times with my kids, and it works out great. After a couple of times, you're a pro- and so are they. I always sort of stay on flight-watch duties that day to make sure everything is running according to plan, and everyone is in place when and where they need to be. And I always remember to CALL THE TRAVEL CENTER.

Ok. That's it.

CALL THE TRAVEL CENTER.

That's all.