Fluid threats remain in focus

The alleged attempt to blow up Northwest Airlines Flight 253 on 25 December 2009 has once again highlighted the role of liquids in the terrorist threat to aviation.

A passenger in a window seat allegedly attempted to detonate a bomb consisting of over 80 g of high-explosive pentaerythritol tetranitrate (PETN)and a liquid thought to be an accelerant.

This incident brings into sharp focus the debate among European governments and aviation authorities on the type of liquid-screening technologies to be deployed at the checkpoint. Proposals from the European Commission (EC) envisage deployment of such devices in 2011 for transit passengers and 2013 for all travellers at airports.

Aviation security officials in Europe have discussed the merits of so-called Type C liquid-detection systems (which would enable an unrestricted volume of liquid to be screened outside the carry-on bag), or whether it would be more appropriate for airports to wait for a Type D capability to become available (which would in effect move further towards the conditions in place before the foiled August 2006 liquid explosives plot).

With the liquid threat clearly high on the agenda again, it seems inevitable that a Type C liquid-threat detection solution will emerge in airports sooner rather than later, with bottle scanners for alarm resolution. Recently conducted research suggests Type C may be a better solution in the airport environment in any case, since studies suggest better throughput due to lower false-alarm rates.