I just flew in June, and I couldn't even take my roll I had bought at Starbucks through the check out, so I'd suggest planning on buying stuff there at one of the convenient stores. They have milk and stuff, plus lots of different types of snacks that would be good for a toddler. I have one piece of advice though....don't overdue your packing. We flew with our 1 year old and 2 year old on a 4 hour flight, and I was so worried about keeping them busy that I had 4 bags, and it was AWFUL carrying it all through the airport, and keeping it all somewhat organized on the actual flight. I recommend you grabbing a few things that he enjoys doing, and stick with that. If you have a laptop, I would bring his favorite movie to watch. I brought coloring book/crayons, and a magnetic puzzle that kept mine the most occupied during the flight. Also, I know you said you want nutritious stuff, but buy a few suckers before you board just in case you need something to keep him quiet and happy, just in case he has a meltdown. My two year old had a little episode at first because the takeoff was scary for her, but once I gave her a lollipop (which is a pretty big treat for my kids since they don't eat candy very often), she was fine.