Take along a few individual packets of protein powder, then mix it into steamed or cold almond milk from the airport Starbucks.
The most delicious, inexpensive, healthy snack are the little packets of Dang Coconut Chips. They're made with only three ingredients---coconut, cane sugar, and salt.
Trader Joe's Crunchy Beans & Peas
Stock up on a bag or two of crunchy, dehydrated beans or peas from the snack section of Trader Joe's. These are a good healthy alternative for potato chips and are totally addicting.
There's nothing easier or more wholesome than bringing along a banana, apple, or pear on your flight.