As I pointed out in another thread, banning passenger's carry-on liquids doesn't really remove the threat.
As security gurus have already suggested, so-called Binary Explosives could quite easily be smuggled onboard an airplane, by using the co-opted services of ground staff.
Anyone visiting Heathrow and Gatwick, for example, quickly realises that a vast amount of support services are staffed by ethnic groups, earning minimum wage: more worrying, in the dash for profit, whole chunks of services are outsourced: and it is a matter of record, that outsource outfits have been notoriously cavalier in checking references: particularly for agency staff. Thus workers can be twice and three times removed from both the airport managing authorities and the airlines.
Probably, one of the biggest current jokes in the UK is how so-called "Security" staff, checked after significant incidents, have been discovered to be illegal immigrants with false ID.........................as have cleaning staff, given totally free access to important buildings when everyone else has gone home.
Paq
