It's why we carry liquids in limited amounts and clear plastic bags. It's why many flyers have to remove their shoes and have them screened. It's also why we sometimes have our hands swabbed and tested at airports. The threat of explosives being brought aboard passenger aircraft has been the focus of aviation security measures but if recent test results prove viable, there could be a way to make the cargo hold of aircraft virtually bomb proof.

Bomb-proof lining, consisting of layers of strong and impact resistant composites, could ease concerns in the aviation community that one day an explosive could make its way to the cargo hold of a passenger aircraft. Tests were recently conducted in England by an international team of scientists and the results were very encouraging. Until now, the only tests done on the materials involved laboratory-based explosive tests but this time actual aircraft were used. Old planes at Cotswold Airport in Gloucestershire were used to test explosions inside cargo containers. The aircraft with the bomb-proof lining in the cargo hold did not suffer structural damage after the test explosion. The one without the lining did.

The materials used in the uniquely named Fly-Bag allow the lining to expand and absorb the impact and heat of an explosion without tearing. If cargo containers can be lined with this material, which is lightweight, it could save the integrity of an aircraft fuselage if an explosion occurs at a high altitude. Prior to the creation of the Fly-Bag, another consideration for making cargo holds bomb resistant involved reinforced containers which some airlines have considered too heavy and expensive.

The flexibility of the Fly-Bag extends beyond the materials it's made from. The technology can be used to drape the interior of cargo holds in narrow-body aircraft which do not use separate cargo containers. Smaller versions can be kept inside the aircraft cabin to secure a suspected explosive device if found inside the passenger compartment.

The developments are encouraging. If the technology is implemented and airlines find the Fly-Bag solution cost effective, a layer of security just over a millimeter thick could bring great peace of mind to an industry that is constantly trying to stay one step ahead of terrorists.