I'm not saying that it is an easy job for the Transportation Security Administration to decide what can and cannot be safely carried on to a plane. I'm not saying that. But at some point, as the TSA makes monthly, micro-detailed changes to the types of knives, sporting goods and snow globes that can be carried on board, the whole exercise starts to seem quite farcical and more than a little random. As discussed here in December, one of the most recent TSA policy changes gave an "OK" to check snow globes in baggage. But not all snow globes. Only snow globes that "appear to contain less than 3.4 ounces (approximately tennis ball size)." Whatever. I see (via Doug Cornelius' Compliance Building) that this month, TSA is serving up a new batch of "Changes to Prohibited Items List (PIL)." As Compliance Building notes, travelers still cannot bring a doggone bottle of water on board, but they can now carry on an assortment of knives so long as the blade is shorter than six centimeters and narrower than 1/2 inch. (TSA did not explain why they felt the need to use centimeters for length and inches for the width limits here....

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