Although transport officials believe the Australian regulations will mirror those imposed by the European Union some weeks ago, those apply only to passengers flying to Europe and then making connections to other overseas destinations such as the United States. Australian Transport Minister Mark Vaile said yesterday all international travellers to and from Australia after March 31 with any liquids, aerosols or gels would have to carry them in containers no bigger than 100ml. These would in turn have to be held by each passenger in a one-litre clear plastic bag to be screened independently of other hand luggage, although new regulations would not apply to liquids in checked-in cases carried in aircraft holds.

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.

It's been claimed that the 7/7 bombers used it, but this has not been positively confirmed. Some sources claim that they used C-4, and others that they used RDX. Nevertheless, the belief that they used TATP has stuck with the media, although going about in a crowded city at rush hour with an unstable homebrew explosive in a backpack is not the brightest of all possible moves. It's surprising that none of the attackers enjoyed an unscheduled launch into Paradise.

We asked University of Rhode Island Chemistry Professor Jimmie C. Oxley, who has actual, practical experience with TATP, if this is a reasonable assumption, and she tolds us that merely dumping the precursors together would create "a violent reaction," but not a detonation.

So the fabled binary liquid explosive - that is, the sudden mixing of hydrogen peroxide and acetone with sulfuric acid to create a plane-killing explosion, is out of the question. Meanwhile, making TATP ahead of time carries a risk that the mission will fail due to premature detonation, although it is the only plausible approach.

We've given extraordinary credit to a collection of jihadist wannabes with an exceptionally poor grasp of the mechanics of attacking a plane, whose only hope of success would have been a pure accident. They would have had to succeed in spite of their own ignorance and incompetence, and in spite of being under police surveillance for a year.