Stopped traveling with pony just past 9/11. Returning from a week in SXM and Saba, ponies in checked bags, valves de-pressurized, but sitting in the tank, with a sticky note on them that the valves were lose, could be taken off for inspection if necessary. Sitting on the plane when our names were announced over the speaker. Escorted off the plane by military types, to the tarmac, our bags were produced, opened and ponies pulled out. Had to take the valves out, let inspectors look them over and repack them. Then allowed to return to plane and some interesting looks from fellow passengers. Haven't tried traveling with one since.