Power bars -- or more generically, "nutrition bars" -- were once the province of weight lifters, marathon runners and Tour de France finishers, so they must be a great healthy hunger preventer, right? Well, they will solve your hunger problem that much is true, which is why they've made the list.
But on the down side, you're not running a marathon, lifting weights or racing through the French countryside on a bicycle. You're sitting in an airplane seat, with no good way to burn off all those calories. So you'll want to check the label for low fat, high protein content, and don't go overboard on the calories. Unless you're on a super long flight, one power bar should be plenty to stave off hunger until you can stretch your legs away from the airport.