In August, an Al Qaeda’s plot to simultaneously destroy numerous transatlantic airliners with liquid explosives was thwarted. The plot reportedly involved the use of liquid explosives and other components to be assembled on-board into a bomb, which would then be detonated in-flight.
Many have argued that the new security measures attempt to protect against a non-existent threat. While the security measures are arguable in their efficacy, contrary to the skeptical assertions, the is very real.
Some have argued that small amounts of liquid explosives are not powerful enough to take down an airliner. Indeed, Al Qaeda’s Ramzi Yousef , in a Project Bojinka 1994 test, used a few ounces of nitroglycerin that failed to bring down a 747, but killed a passenger and blew a hole in the side of the aircraft. Nitroglycerin is a very powerful liquid explosive easily made from common chemicals, and is the explosive component of dynamite. This test proved only that a few ounces, not placed in an optimal location, will not always take down a large commercial airliner.
A suicide bomber, with the same amount of explosive, would be able to set off the explosive in an optimal location – such as at the cockpit door, just above the central fuel tank, or other places where a relatively small explosive could destroy the aircraft’s ability to fly. Additionally, there exist a number of powerful liquid explosives, including binary formulations which are stable until the ingredients are mixed.
Others have said it would be too difficult to make a suitable explosive in flight. This is probably because the plot allegedly involved in-flight manufacture of TATP, a popular terrorist explosive. Making TATP is not technically difficult, but the process is time consuming and very hard to conceal, and the explosive is very sensitive, which could result in too small an explosion too soon. One might as well make nitroglycerin on board.
All of this is well known to counter-terrorism officials. After all, TATP is the explosive of choice for Palestinian suicide bombers, and the high sensitivity of the explosive has led to many “work accidents” - the Israeli term for unintentional explosive suicides from premature detonations.
Even so, TATP can be used as a detonator for an otherwise too stable explosive. The “shoe bomber” attempted to set off TATP hidden in his shoes, which was intended to detonate a significant quantity of the very powerful PETN.
Thus, given the considerable terrorist experience with TATP, and Al Qaeda’s previous use of it, TATP could in fact have been pre-made and included only as a trigger.
Thus the plan would have been:
- - Carry aboard a small amount of TATP for use as a detonator
- - Carry aboard a stable liquid explosive, or the component halves of a binary liquid explosive
- - Access (and perhaps mix) the liquid explosive and attach the TATP detonator. This could easily be done quickly in a toilet
- - Either detonate the explosive in the toilet, or run to a sensitive spot and detonate it there. The latter approach would require a short period of protection of the bomber while the TATP was being set off.
Many related approaches are also possible.Hence preventing passengers from transporting liquid explosives onto an aircraft is clearly needed. The current security measures make that transport much harder, but not impossible. Whether they are appropriate is a harder question.
