I've taken Trey with me on 6 flights so far, and 2 of those were three hour, solo trips. On those flights it's mostly a survival game and anything goes, really. But I wanted to share a few things I've learned along the way to make flying with a baby easier. (There are also a ton of helpful suggestions also in this post here from other veteran mamas on Instagram.)
On baby and child ID: TSA requires ID to get through security only at age 18 or older, but each airline has their own rules, and some require additional documentation to get your child a boarding pass. The airlines that we've flown with have required some form of birth date documentation, such as a medical paper from a doctor's visit, etc. Make sure you check or call ahead of time to find out what you'll need.
On the feeding plan: I'm exclusively breastfeeding, but Trey will take a bottle (thank the Lord) so I bring breast milk in a few bottles as well as my nursing cover to have both options. On some of my flights I've been able to nurse Trey (it's almost a guarantee that he'll fall asleep if he's tired while nursing) but sometimes, you happen to be seated in a middle seat and next to a Very Large Man taking up half of your already mini seat, and nursing simply isn't feasible. For this reason, I bring a few full bottles and am always so glad to have them.
On breast milk through security. You can bring as much breast milk as you want through security, it's an exception to the liquids rule. They'll run it through the x-ray and open the bottles and test them again afterwards. Kind of a pain but worth it for me. I love our bottles (Dr. Brown's) but two points: make sure you remove the air vents prior to flying (both because of the altitude/pressure changes to prevent leaks, AND because they make you remove them to test them at security) and also make sure you follow the "max fill line" rule to prevent leaks as well. We've had no leaking issues since implementing those two things when flying.
On what gear to bring. When I flew solo with him, I had a connection, and I knew I needed the car seat and stroller at the gate in order to make it halfway across the airport by myself to my next flight. When you check your car seat/stroller at the gate on a connection, you can choose if you want to have it available at your layover, or if you want it to just stayed checked until you get off at your destination. I needed to have it at the halfway point and was glad I did. (This meant I didn't need a carrier, but if I did, I'd choose something easier to get on like the ergo over a wrap, I know some people who would say the opposite because the ergo is bulkier than a wrap, so it's totally personal preference. Besides the space issue, my other reason for not bringing a carrier is the "no baby wearing while take off/landing" rule, which is such a pain.)
On during the flight. I hesitate to say this publicly, but I think we might have an unusually easy baby. For all the flights I've taken him on so far, he hasn't cried once. He kind of fusses a little bit as he starts to either nurse or drink from a bottle, and then falls asleep and stays asleep for the rest of the flight. I think it might be a combination of the loud noise of the plane and the slight bumpy movements. He sleeps easily in cars too so that could have something to do with it. At first I was worried that his ears weren't popping with the altitude changes in take off and landing, and thought maybe I should wake him up to feed, but he's done that every time and been fine so I don't worry about it anymore.
On your SOS plan. If you're in that very last hour of your all day/cross country/solo travel trip and you're in that middle seat next to that Very Large Man and starting to kind of loose your mind, take your sleeping baby and go to the back of the plane. I stood in the back of the plane and chatted with the flight attendants for the last hour, and just bounced Trey while he slept, and the flight attendants gave me water and snacks and told me stories of when their babies were little. Sometimes you just need a change of scenery. Everyone (mostly) is so willing to help with a baby.
On not sweating the small stuff. Things likely will go wrong, as with all of life. In that same solo travel trip that was kind of a circus, I managed to forget documentation for Trey AND I left all the bottles at security after screening. It all worked out, I was able to provide other documentation and they called me back over the intercom to retrieve the bottles. All fine in the end. Same with my friends who have babies who scream on planes; they remind me that it's likely you'll never see any of those people ever again, AND they were all babies once too. People, generally, get it. I feel like it's more tense for us than it is for them. Having a level headed perspective helps.