According to the respected and irreverent British technology publication The Register, the plot--if it existed--was a joke. Smuggling the component parts of triacetone triperoxide (TATP)--the liquid explosive we've been told was the object of the wannabe jihadis' vengeance fantasies--and successfully mixing them into a brew powerful enough to bring down a plane would require skills far beyond the capabilities of, well, anyone.
"First," wrote The Register, "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...Take your hydrogen peroxide, acetone, and sulfuric acid, measure them very carefully, and put them into drink 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.
"It's best to fly first class and order champagne. The bucket full of ice water, which the airline ought to supply, might possibly be adequate...Once the plane is over the ocean, very discreetly bring all of your gear into the toilet. You might need to make several trips to avoid drawing attention. Once your kit is in place, put a beaker containing the peroxide/acetone mixture into the ice water bath (champagne bucket), and start adding the acid, drop by drop, while stirring constantly. Watch the reaction temperature carefully. The mixture will heat, and if it gets too hot, you'll end up with a weak explosive. In fact, if it gets really hot, you'll get a premature explosion possibly sufficient to kill you, but probably no one else.
"After a few hours--assuming, by some miracle, that the fumes haven't overcome you or alerted passengers or the flight crew to your activities--you'll have a quantity of TATP with which to carry out your mission. Now all you need to do is dry it for an hour or two."