Mariakirk, see my post early on in this thread. i'm sure your GP could prescribe something for your husband. if not, speak with a local friendly pharmacist who might be able to reccomend an over the counter remady.
as a final resort, make sure he has nothing to drink in the airport (you might think alcohol will help him relax, however this will only excassibate the problem, and make it worse). breathing into a paper bag can also help calm people down when having a panic attack, so it might be a good idea to take one with you. you could also take something along that will help take his mind of the fact he is flying (like a portable music player, a good book, some toys / games he can play with the kids).
have a good flight, and tell him not to worry...........