We are well trained now: when travelling on planes, we know we can’t put anything over 100 millilitres into our carry-on luggage, and any mistaken attempts end with forfeiting our valued moisturizers and designer water bottles. Through hard battles lost, we’ve succumbed to the demands of airport security authorities, all for the belief that this restriction makes us safer. And now as we pause to consider, we wonder: why can’t we put liquids, gels, and aerosols in bottles larger than 100 ml, and why must all these bottles fit into a one-litre plastic bag?
Our first guess is partly right: it is something to do with a potential terrorist threat from liquid explosives. But solid explosives are widespread too. And in focusing our tunnel vision on individual passengers, we forget that a bomb in checked luggage can be large enough to take down a plane, while a few harmful millilitres in a purse may only blow out a window.
The so-called liquid limit got its start on August 10, 2006, when UK police arrested twenty-one suspects in London over a plot to detonate the liquid form of explosive TATP aboard as many as ten flights bound for Canada and the US. Immediately, the fortress gates of the three countries slammed shut: transport authorities banned all liquids (excepting baby formula, prescription medications, and a few others), and the US and UK even banned carry-on luggage. A month and a half later, the US Transportation Security Administration introduced its 3-1-1 rule, allowing 3.4 ounces (100 ml) of liquid per container, with all containers to fit in one quart-sized (950 ml) bag, per passenger. Another month and a half after that, Transport Canada imposed a 100 ml/1 litre rule for travellers at all Canadian airports. (more…)