What are some foods I can pack for my husband that he can take on an Airplane?

Check with the experts: http://www.tsa.gov/travelers/airtravel/prohibited/permitted-prohibited-items.shtm

Any food that has NO LIQUID of any kind (sauces, watery substances). Dry foods are allowed. You can pack him chips, cookies, hard candies, sandwich with NO mayo or musturd, Salads (no dressing), A hot dog (no ketchup), steak, rice, chicken, hamburger, whatever you can fit in your tupperware. Remember, NO LIQUIDS of any kind. I always take Hawaiian Airlines or ATA Airlines (since I live in Hawaii) they are generous when it comes to food but....they do not give much to drink. They always give small amounts of water, soda & juice. During my flight times, I felt DEHYDRATED. There's no drinks allowed on board unless you have some kind of health/sickness issue where a doctor's note will be needed.

Starkist has vacuum sealed Tuna paks. There are other similar products, in the same area, at the store where you shop.