Not very.
http://www.theregister.co.uk/2006/08/17/flying_toilet_terror_labs/print.html We're told that the suspects were planning to use TATP, or triacetone triperoxide, a high explosive that supposedly can be made from common household chemicals unlikely to be caught by airport screeners. A little hair dye, drain cleaner, and paint thinner - all easily concealed in drinks bottles - and the forces of evil have effectively smuggled a deadly bomb onboard your plane. <...>
Making a quantity of TATP sufficient to bring down an airplane is not quite as simple as ducking into the toilet and mixing two harmless liquids together.
First, you've got to get adequately concentrated hydrogen peroxide. This is hard to come by, so a large quantity of the three per cent solution sold in pharmacies might have to be concentrated by boiling off the water. Only this is risky, and can lead to mission failure by means of burning down your makeshift lab before a single infidel has been harmed.
But let's assume that you can obtain it in the required concentration, or cook it from a dilute solution without ruining your operation. Fine. The remaining ingredients, acetone and sulfuric acid, are far easier to obtain, and we can assume that you've got them on hand.
Now for the fun part. Take your hydrogen peroxide, acetone, and sulfuric acid, measure them very carefully, and put them into drinks bottles for convenient smuggling onto a plane. It's all right to mix the peroxide and acetone in one container, so long as it remains cool. Don't forget to bring several frozen gel-packs (preferably in a Styrofoam chiller deceptively marked "perishable foods"), a thermometer, a large beaker, a stirring rod, and a medicine dropper. You're going to need them.
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