I think NattoGuy has summed it up beautifully.I’m only going to relay my personal experience, as a positive story, nothing more. YMMV, naturally.
My Sebastian is a very jumpy, neurotic little bundle of joy. However, I was going on a long vacation, and had absolutely nowhere to leave her. My friend wouldn’t care for her properly, my family owns a very territorial pup (and Mom’s allergic to cats, to boot), and the local kennel had just been on the news about a dog that had escaped his cage and killed a cat. Kind of put me off. So, I decided, my darling would have to come with me.
I took her to the vet to get all of her proper shots (we were leaving the country) and some papers to show customs. I talked to the vet about sedatives, and decided against them. Sebastian has bad reactions to many meds, so I figured I would just keep a close eye on her. I flew Air Canada, and they allowed me to bring her in as carry-on. Her carrier was made of canvas and nylon - much easier to get under the seat that way!
She fasted the day before the flight, and in her kennel I put her favourite blanket, and some of her favourite toys. I brought her treats, and a bowl for water and one for food. I kept a safety collar with her nametag and contact info on her at all times. I also brought a harness with a leash, so when we changed flights, I could take her outside to allow her to do her business, and stretch her little legs out for a bit - it’s no fun being cramped in that little carrier! (be sure the carrier is at least large enough for your cat to stand up and turn around in). She ate very little, but she drank quite a bit. Whenever I could, I would reach in to stroke her and reassure her, and just let her know I was near. She’s normally very vocal, but for most of the trip, she was quiet.
The final 45 minutes of our trip, she began to meow, and I honestly can’t blame her, poor dear. After all, I just wasted her whole damn day, and disrupted her schedule! As soon as we got to our destination, my then-friend (now hubby!) had a fresh litter box waiting for her, since i alerted him she would be coming. I let her out immediately, and she was fine. A little disoriented, a lot tired, but okay. No “accidents” in the carrier at all.
In a strange turn of events, I never returned from that vacation, found the love of my life and married him, and never had to make that plane trip back. I don’t know if I would put her through it again (I don’t know if I want to go through it again, what a tiring trip!), but she did handle it wonderfully, better than I expected her to.
She became a US citizen before I did - she’s all licensed with the county with her own ID number and everything! (why couldn’t it have been that easy for me? Heck, I’ll even wear a chip if they want me to!)
I wish you the best with your cat!