Experts: Planes Vulnerable to Bombs Built on Board

The next terrorist attacks on civilian aircraft could be carried out by passengers who hide their bomb ingredients in innocent-looking containers for talcum powder, baby formula or medicine bottles and assemble their weapon behind a locked restroom door, security experts warn.

The announcement Thursday of a foiled terror plot aiming to blow up flights from London to the United States using explosives hidden in hand luggage pointed to a potential new chapter in the battle against airline terrorism: a world of hours-long security checks, visual inspections of prescription drugs, and bans on bringing liquids or laptops on board.

Several bomb-disposal experts and troubleshooters for airline security interviewed by The Associated Press said mobile phones, computers, wrist watches or anything else with a battery should be prohibited from flights.

Perhaps most chillingly, they warn that security staff at airports are not looking for the right things anymore - and the change in tactics required is likely to overwhelm current security standards.

"That theater we see, of people taking off shoes, is not going to stop a suicide bomber. The terrorists have already sniffed out the weak spots and are adopting new tactics," said Irish security analyst Tom Clonan, who noted that security measures usually adapt to the last attack, not the next threat.

He said that a terrorist group will almost certainly try to blow up a plane with a bomb assembled on board unless security measures improved fundamentally.

Anti-terrorist authorities in Britain and the United States declined to describe the bomb design used by terrorists in the foiled plot - whether they were primarily liquid or, more likely, contained liquids in a more complex ingredient list.

Whatever the case, experts predicted passengers may soon have to change their travel habits radically.

"Every businessman needs to have his laptop on a long-haul flight, and now you won't be able to. Even a battery-operated watch would provide enough power for a detonator. All you need is one shock," said Alan Hatcher, managing director of the International School for Security and Explosives Education in Salisbury, England.

Airlines have toyed with the idea of banning innocuous personal-care items from carry-on luggage following previous security scares, only to have the focus switch elsewhere because of the mammoth difficulty of enforcing tougher rules. Thursday's announcement dramatically raises the likelihood that security will come first no matter what the logistical hurdles.

The technology for the kind of liquid or crystallized explosives possibly involved in the thwarted terror plot is not new.

The threat first appeared in January 1995 in the Philippines, when police stumbled upon a suspected al-Qaida plot to target U.S.-bound, long-haul planes with bombs based on nitroglycerine carried on board in containers for contact-lens solution.

At that time, aviation authorities announced plans to ban aerosols, bottled gels and containers of liquids holding more than 30 milliliters on U.S. airliners departing Manila, an idea never properly enforced.

Even then, baby formula was excluded from the limits - even though, in its powdered form, it could provide a good vehicle for masking crystallized explosives.

A decade later in Belfast, Northern Ireland, an Algerian man was convicted of possessing 25 computer disk drives detailing how to bring down an aircraft using, among other things, crystallized explosives hidden in a container of talcum powder.

During that trial an FBI explosives expert, Donald Sachtleben, testified he had built and successfully detonated three bombs based on the instructions found in the Algerian's home.

Despite this decade-old knowledge, security officials in Dublin and across Europe still permit passengers to carry on a wide range of receptacles without any visual inspection.

And the increasing probability that terrorists will try to strike with explosive components hidden in hand-luggage has been accompanied by a trend among discount airlines to encourage passengers to bring more carry-on baggage. In recent months Europe's market-leading airline, Irish budget carrier Ryanair, has imposed a mandatory charge on all check-in luggage; an Irish competitor, Aer Lingus, has announced plans to follow suit.

"I'm really surprised the Irish aviation authority hasn't stepped in to moderate this rush to hand luggage by airlines," said aviation expert Gerry Byrne. "All our airport security has been geared towards baggage going into the hold. ... It will overwhelm security if the emphasis is suddenly switched to hand baggage."

A British security expert, Steve Park, said the likely scenario would involve a two- or three-member terror team boarding the same flight, each carrying a different part of the bomb to be made. "They could combine resources on the plane. That would be perfectly possible on a busy flight," he said.

Critical to conventional bombs is a power source to trigger a detonator. Clonan said cell phones could provide an ideal power-timer unit for a bomb.

"In midflight you could go into the toilet, attach the mobile phone to the explosives and, as the plane makes a final approach over a densely populated urban area, you detonate it," he said. To puncture an aircraft's fuselage would require an explosive charge "half the size of a cigarette packet," he said.

Hatcher said "liquid bombs" were not the most likely explosive. He said it was far more likely that a terrorist cell would try to smuggle on board explosives in crystalline or powder form and to combine it with an acid-based compound.

Homeland Security Secretary Michael Chertoff warned Thursday of precisely that threat: "benign" materials smuggled on board and mixed to create bomb. He said authorities were analyzing to see how to protect against such a threat.

Hatcher said terrorists might also construct an on-board incendiary bomb based on paraffin or petrol, which if ignited in the mid-Atlantic could destroy an aircraft before it could land.

None of these items, he noted, could be detected by a typical US$5 million (euro4 million) X-ray. Hands-on inspection was the only way to tell if a dark-plastic medicine vial really contains what it says on the label.

"You'll have to carry your prescription and prove to security that the medicine really is what it is. But for 20 million people a year going through Heathrow? How do you do that?" Hatcher said, foreseeing a future airport arrivals hall with five-hour security checks.

And that scenario, he said, points to a future likely target for terrorists - detonating bombs in an airport terminal, not on a plane.

"You can carry a bag into the center of an airport with thousands of people around you before you are ever screened. That, too, must change," he said.