Transporting a Lemon Pound Cake (moistened by lemon syrup)

Thank you, all! I am going for tupperware as you all suggested.

Another vote for tupperware. I once took a birthday cake on a 4 hour train trip followed by a 2 hour drive before it reached a fridge again, and I wrapped it in plastic wrap and then foil. It was difficult to keep worrying about it getting squished on the way, and it wasn't even frosted until I reached my destination. Your syrup could also cause leakage issues, which could get really sticky too. If you decide not to do tupperware, I would suggest adding a layer or two of plastic bags tied well.

I've taken a fully frosted layer cake and a cheesecake (yep, it didn't get flagged for being a gel) on a plane before and I would advise keeping it in the Tupperware. The more hard sided the better to protect the cake, plus if those TSA folks get bitchy about what that lump is and makes you unwrap it, it's easier to get it back into a plastic container than rewrapping plastic or aluminum foil. I don't know about you but the main cabin of plane is always cold, so putting the cake (in a box) under the seat in front of you is no problem.

Oh and when they ask you want that thing is, just tell them that it's a pound cake. Leave out any mention of liquid (i.e. syrup). I also find that the prettier the packaging the less inclined they are to hassle you about it. Remember that cheesecake I brought on a plane? I had put in into a beautiful paper box that once packaged Korean mochi from Seoul. The TSA agent was so smitten with the box, she only asked me where I got my cheesecake from.

Recently, I had sent a marble pound cake to West Coast from East Coast, and I had places the cake in an aluminum foil tin and covered it first with cling wrap and then with aluminum foil , it reached so well in that same way.
Rather, you could also buy those cardboard bread loaf sized boxes available at many places. I think so Sur La Table carries them. Or else Tupperware is your choice.

I think you should keep it in the tupperware. It is surprisingly warm on the plane in storage compartments and your cake could get really soft and break apart unless you are very careful. I also think it could get a bit sweaty wrapped in cellophane. Depending on your carry on luggage situation, you could put the tupperware in a little shopping bag and slide it under the seat in front of you.