I've carried many neon sculptures and signs aboard an aircraft, although not since 9/11. They ALWAYS ask to view it, because of the transformer and the amount of metal in the frame. I would take it as carry on luggage, pack it very well, but be able to open up the container so they can examine it. I always mention that it is fragile as it goes through screening.

I would not check it as luggage.

Good post, NWAMileageSlave.

Linda