1. What travels well--Bite-sized foods that taste good at room temperature are your best bet. EatBoutique.com recommends fruit, chocolate, and cheese cubes. If you want something a little more gourmet, go for spring rolls or hand pies or even mini-quiches.
Also try snack mixes like chocolate-dipped pretzels, hard candies and crackers. If you want to bring a sandwich, put it on a bagel. They are firmer and can handle the abuse of being shoved in your pocket. Not too much mustard or mayo, so it doesn't get soggy if you decide to nap first.
2. What if you're on a special diet?--Vegetarians find very few choices at airports. ChefSteps.com recommends mujadara, a Middle Eastern pilaf of rice, lentils and caramelized onions. It's great for a plane because it is hearty, filling and compact. If you're following a gluten-free diet, pack cheese sticks, protein bars, and a sandwich made at home.
4. What to leave home--Kimchi, runny French cheeses and other strongly-scented foods are a no-no for air travel. Tuna fish is also a no-no. It's totally rude to bring a tuna fish sandwich on a plane.
5. Worst Foods to Take on a Plane--Clam chowder is not only stinky, it's potentially messy. When you bring messy food on a plane, you can pretty much count on getting bumped so your nice shirt will end up nasty and you'll end up sitting there gross for four hours. Or, worse, you can spill on other travelers. Even fruit can be a problem. When you're sitting next to someone and they're eating something really juicy or messy like an orange and it's dripping and they're slurping and dropping orange peels on your lap. That sucks. Also stay away from cheese puffs. There aren't enough napkins.