How long is your flight, and why are you taking the cat with you? As for sedatives, you want to avoid the usual Acepromazine as it decreases a cat's ability to regulate temperature which could lead to problems. I have heard of people giving their cats xanax but I have never tried it myself. One thing I would definitely recommend is that you get a secure harness or walking jacket to keep on him for when you have to take him out to walk through security.
Hear, hear!
Giving sedatives to cats for flights does more harm than good in my opinion. If a cat needs a sedative to fly, don´t.
A cat that gets a sedative will respond very negatively to the associated loss of orientation, control and coordination, this is very stressful, in addition to the effect Patti describes. Sedatives affect the whole body!
Some people sedate cats because they (the cats) make a fuss in the cage during a drive: Too bad, live with it. Strange thing is, in all my career I have NEVER had a problem with a cat in a car: put in cage, restrain cage, drive. If you CHOOSE to "converse" (*) with your cat you may be in for a long conversation, personally at best I stick a finger into the cage to reassure.
* One can imagine the following:
-Miaow
-Be quiet
-(slave is answering me!) MIAAAAOW!
-Shut up, noisy!
-(Uh! Slave wants to talk) Miaaaow miaaaaow miaaaaaaaaauuuuooow
-Shut up horrible beast!
-(I really want to sleep, but if slave insists) Miaaaaw miaw miaaow!!! MIAAUW!
...and so on for a hundred miles ...
**with a sedative, imagine a drunk teenager in the back seat being taken home at three in the morning...