We used to eat these when camping and on hiking trips of several days when space was a premium (supplied by military father of good friend). They were vile! Vile vile vile! And on top of that, they had so many calories and energy, I felt like I could carry a horse around all day long without such trouble. I also hardly ate anything else.

Plus, in order to "cook" and properly prepare the food, you had to have that heating pack thing, which in the stuff I had was a highly exothermic (heat) chemical reaction to warm the food. Without them, the MRE may not be edible, and I doubt security types will enjoy you bringing aboard something producing such reactions.

Hardly the kind of stuff suitable for eating when lethargic on an aircraft or hotel room. Much better to buy a sandwich or bagel in the airport.