The 747 ABL is like a boys own chemistry set inside. The very thought of a RAF Plod doing a DAC check on it makes me giggle. Everything is either explosive, corrosive, inflammable or usually all three. The theory is great, but you have to catch the offending article during the launch phase, which means you have to be within a specific radius of the potential launch site. Thank God no-one has invented portable launchers - oh wait...