Counter Terror Gazette

Controlling Explosions: by timers, barometric devices, switches and more

25 Oct 2010

How does the terrorist of 2010 ensure that their device detonates at the intended time or location? Andy Oppenheimer studies the various control mechanisms that can be used and what they might look like on physical inspection or under X-ray examination. 

On Christmas Day 2009, an attempt by 23-year-old Nigerian Umar Farouk Abdulmutallab to blow up Northwest Airlines Flight 253 bound for Detroit failed – most likely due to a faulty detonation sequence. The would-be bomber, whose device incorporated a cocktail of explosives hidden in his underpants, is said to have tried to initiate it by injecting an acid into the main charge of Pentaerythritol (PETN), a proven, stable high-explosive combined with the peroxide-based homemade explosive Triacetone Triperoxide (TATP). It is believed the injected acid was intended to ignite the TATP in order to, in turn, detonate the PETN – but the normally highly volatile TATP did not ignite as planned, as the acid injected into the explosives may not have produced enough heat. 

This botched attempt at mass murder in the skies (and the failed Times Square, New York car bomb attempt on 1 May 2010) illustrated a gap in terrorists learning curve with regard to detonation sequences and more generally, the body of knowledge and expertise on making bombs explode at exactly the right time, place, and to the maximum effect desired. Unless an airborne improvised explosive device (IED) has all the components functioning at once, failure is possible – and the more links in the chain of initiation, the more likely it is to malfunction. Such devices, although appearing crude, are complex enough to require testing in real time and in the actual setting for the attack – a virtual impossibility for most terrorist groups. MORE ONLINE