The costs and time involved in screening the millions of packages transported by air every day could bust the airfreight business.
No overnight solution to cargo security
A single sentiment has united governments worldwide in the eight days since bombs were found in air cargo consignments in Dubai and England: the absolute need to do something soon to enhance the security of airfreight.
Over those same eight days, however, a stark reality has also emerged: nobody can quite agree what should be done, by whom and when.
A few days ago, the International Air Transport Association (IATA) warned governments against "knee-jerk reactions". Giovanni Bisignani, the association's head, said at an aviation security conference in Frankfurt: "Effective solutions are not developed unilaterally or in haste."
While IATA accepts that improvements are needed in the wake of the Yemeni printer cartridge bombs, the fact is that, to the airline industry, individual countries and businesses worldwide, air cargo is an essential tool of global trade, with just over one-third of the total value of goods traded internationally being transported by air.
The costs involved in screening every single one of the many millions of items that take to the air each day, plus the time delays that would result from such screening, could be so great that the air cargo business would virtually cease to exist.
"In a worst-case scenario, it would stop world trade," said James Halstead, a senior associate with the London-based consultancy Aviation Economics. "UPS and FedEx would probably go bust; we'd have a full disaster scenario. The cost of the extra effort involved in putting in security checks to find these sorts of bombs would be almost too much to consider."
Theoretically, every item of cargo carried on passenger flights entering, or flying within, the United States has been scanned since August. In fact, the Transportation Security Administration admits that only 65 per cent of cargo on incoming foreign flights was subject to scrutiny that month.
And screening cargo just on passenger flights in the United States involves about 9,000 staff and an estimated $700 million (Dh2.6billion) a year in additional costs, according to the Airforwarders Association.
Aviation experts point out that only about nine million kilograms daily - 16 per cent of the total of airfreight - are loaded on passenger flights, with the remainder on specialist air cargo carriers such as UPS, FedEx and DHL.
The one piece of good news for carriers is that 80 per cent of all cargo originates from regular, trusted businesses. It is the remaining 20 per cent, which includes the bombs posted from Yemen, that poses the real danger.
"They do as much checking as they can in many places," Mr Halstead said, "but it's the danger of these small items that is the problem."
Given the practical problems of screening and the fact that many poorer countries will not be able to afford for years the new, sophisticated detection devices being developed, there is a growing belief that good intelligence - even at the most basic level of clerical staff checking senders' identities and packages' addresses - will be essential.
"Even if you have a very good screening system, it won't detect everything," Saif al Suwaidi, the director general of the UAE's General Civil Aviation Authority, said this week. "The key is to have very good intelligence and exchange of intelligence between countries. That is what we are trying to do now."
It was, of course, intelligence from a Saudi dissident that led to the discovery of the bombs in Dubai and England. The fallibility of detection devices was demonstrated at East Midlands Airport in Leicestershire, UK, where the first sweep of the UPS plane failed to find anything suspicious.
Roland Alford, the managing director of Alford Technologies, a UK company that develops bomb-disposal systems, said the PETN explosive hidden in the cartridges can be hard to detect by electronic screening devices, but is much simpler to detect by chemical testing.
Pentaerythritol tetranitrate is one of the most common explosives and traces of it can be easily picked up on people, their clothing or packages and bags via swabbing, he told the BBC.
But sniffer dogs and existing scanners cannot detect it unless the atmosphere from within a sealed container leaks out into the air, Mr Alford said. Even swabs might be of no use if the explosive and triggering mechanism were in hermetically sealed containers.
"In this case, they used the fact that it was a powder in a compartment within a device [a printer] in which you would expect to find powder," he said. "It was a very clever way of disguising it."
The fact that the bomb found in Dubai had been transported from Sana'a on two Qatar Airways passenger flights has sounded understandable alarm bells throughout the Gulf, where security at most airports is considered markedly better than elsewhere in Asia and the Middle East.
Theodore Karasik, the director of research and development at the Institute for Near East and Gulf Military Analysis in Dubai, believes even greater security measures must be implemented at Gulf airports.
"There needs to be a complete re-examination of security because of the fact that the bomb was sent from Yemen went on a passenger plane to and out of Qatar," he said.
"Sending packages through the mail like this is not something that's new. What is new is the sophistication of the devices. I know for a fact that Dubai double-screens stuff; that needs to be duplicated throughout the region."
Thomas de Maizière, the interior minister in Germany, where the UPS plane set off for Britain before the bomb was detected, agrees that screening needs to be improved worldwide.
"Airfreight has been relatively under-monitored up to now. Evidently, they [the terrorists] recognised that and exploited it. This means changes for the airfreight business," he said.
But Dierk Mueller, the general manager of the American Chamber of Commerce in Germany, told Deutsche Welle that proposals for extra checks were little more than a blanket for politicians eager to cover their backs.
He pointed out that the US government's bid to have all air and sea containers checked upon entering the country had proved impossible to implement.
"Even if you have all the money in the world, no one knows how to do it," he said. "Even if all the major western hemisphere countries say: 'We have 100-per-cent safety procedures', they would still need all the paperwork - stamps and stamps and papers and papers. There is no way to do it 100 per cent. You always have some countries not participating."
Philip Butterworth-Hayes, a British aviation specialist, agrees that many practical problems exist. "The technology exists," he said. "It's horrendously expensive and will take many years to install at all the various cargo depots and freight-forwarding places.
"If you add up all the places cargo can access the air side at airports, there are many thousands of places, and to put screening units in all those places is very complicated."
Existing security costs, let alone new ones, are already of serious concern to many airport operators. The European branch of the Airport Council International estimates that security currently accounts for 35 per cent of airport operating costs across the continent, compared with between five per cent and eight per cent before the 9/11 attacks. Forty per cent of all airport employees at Europe's 313 airports are now security-related staff.
Magnus Ranstorp, from the Swedish National Defence College, said it would simply be too expensive to try to establish a foolproof screening system because terrorists are constantly changing tactics of concealment.
Instead, he proposes that efforts should be made to keep cargo off passenger planes, as well as eliminating cargo services from high-risk countries.
"You have to economise, and this [sending bombs by air cargo] is not a very frequent tactic," he said. "Now you eliminate Yemen as a route, that will partially take care of the problem.
"You just have to be more rigorous because these groups are constantly coming up with innovations. They will move onto something else."
Airlines, however, will baulk at any plans to remove cargo from passenger flights. Freight provides a very useful money earner for airlines at a time when many are struggling to make ends meet.
As David Learmount, the safety editor of Flight Global magazine, says: "There is no silver bullet to this problem. Lessons need to be learnt from this, but we cannot change things overnight."