Would you trust the human eye to spot a bomb?

Airline passengers will undergo full body scans as security measures are stepped up after the alleged plan to blow up a plane on Christmas Day. But the technology is only ever as good as the people who operate it, says Chris Yates.

Security measures for British air passengers are about to get a lot more stringent.

After the alleged attempt to bomb a transatlantic passenger plane over the US on Christmas Day, full body scanners in major British airports have been given the go-ahead.

In addition to these "naked" imaging scanners, there will be a greater reliance on explosive residue detectors and a full scale review of the security system that exists in this country.

Full body scanners, or whole body imaging (WMI), as the technology is known in the trade, will allow airport security staff to see beneath passenger clothing to ensure travelers are not carrying concealed weapons of most types.

The equipment has been around for some time, with a current trial at Manchester airport, but until now plans to roll it out have been held back by concerns about privacy. The scanners effectively render a naked image of each passenger - highlighting any objects stored close to the body as well as more intimate details.

Yet the fact such concerns have been swiftly swept aside in the immediate aftermath of the Christmas Day scare is evidence of how international air travellers are about to witness another tightening of the security net.

But how effective are these full body scanners and are we relying on them too heavily?

Regardless of whether Whole Body Imaging (WMI) could have identified the explosive device allegedly used in the failed Christmas Day attack, this type of technology in the airport environment is a potential game changer for the safety of air passengers. It also gives security personnel much needed additional capability.

Human error

But it cannot be seen as the panacea to the threats we face today.

Full body scanners are often only as good as the people paid to be behind the screens, analysing the succession of complex images scrolling in front of their eyes.

Staff monitoring screens typically only do so for a two-hour stretch - one of a rotation of duties to stop them from getting bored.

But even then, they are only human and it's a human frailty that when attention is focused on a mundane task, it can easily wander - distracted by the sight of an attractive man or woman or a passing celebrity.

There are moves at the moment to relocate the operatives looking at screens to a remote area - a darkened room where there are no distractions. It's one of the ways that the security industry is looking at improving scanning and minimising human error.

So maybe the alternative is to go for something that minimises, even sidesteps, human error. entirely. With some emerging technologies, such as liquid detectors, the machines themselves make the call.

Given that the alleged Christmas Day plot is said to have relied on liquid for the in-flight bomb, there is clearly a case for liquid detectors at airports sooner rather than later.

The hardware and software is already available.

Green light scanner

A bottle scanner device has undergone pilot trials at Newcastle Airport and is being assessed by Manchester airport.

The scanner is an ingenious piece of kit - a standalone system providing a highly accurate means to positively verify whether the content of a bottle is safe for carriage in the passenger cabin or otherwise. It literally gives a green light for "OK" or a red light.

Or there is a piece of technology which can be used with existing baggage X-ray systems to detect liquid explosives and chemical threats in real time, for a fraction of the cost of deploying new hardware.

Gordon Brown has also signalled that passengers could see greater use of explosive residue detection systems that are already deployed at UK airports for random screening of passenger belongings.

Many of us are familiar with having items of hand luggage swabbed and analysed by these labour intensive devices at airports. However, this method of detection is evolving dramatically.

An explosive residue detection system developed by Loughborough University and presently being commercialised can remotely scan crowded areas, such as airports and train stations, automatically alerting an operator if it detects traces of explosives.

A hand-held variant of the system is also under development and is ideally suited to deployment in the central screening areas within airports.

PR exercise?

Of course, it could be pointed out that for all the money and time spent on elaborate scanning equipment, as far as I know, they have yet to be instrumental in foiling a terrorist plot.

Indeed, many people will say that scanning at airports is nothing but a PR exercise - there to reassure the overwhelming majority of law-abiding passengers while also acting as a deterrent for violent fanatics.

That could perhaps have been said of the old style X-ray scanners. But the level of sophistication we have nowadays gives much greater capability to detect weapons.

Yet security at airports is as much about technique as technology. The technique involves, amongst other things, passenger profiling. Rudimentary forms of profiling have been commonplace at airports for very many years and we're all used to the sort of basic questions asked of us prior to and during the check in process.

Traditionally, the UK has shied away from full on profiling of the kind passengers travelling to Israel might undergo for example. However, there is now a strong case for much greater use of this technique at airports.

Civil liberties groups have long been opposed to passenger profiling, citing issues surrounding whether individuals might be profiled on grounds of ethnic background and so forth. There is though no reason why greater profiling cannot be conducted without recourse to contentious issues such as race and religion.

The aviation industry routinely collects vast amounts of data on our travelling habits that can be used to build up an extremely useful profile. Information regarding the destination, frequency and duration of overseas trips allows those tasked with ensuring the security of flights to positively identify passengers who may travel to regions of the world determined to be high-risk for example. That enables higher levels of security to be applied to that person as he or she passes through the airport.

What is required is a system of systems comprising both technique and technology. The technique must include greater use of passenger profiling whilst the technology must include advanced tools giving greater detection capability.

Such techniques, when combined with greater use of advanced technologies, give us much greater detection capability on the frontline at our airports.

Chris Yates is an aviation security analyst with Jane's Information Group.

Obama orders air security review after jet bomb attempt

US President Barack Obama has ordered a review of air security measures after a Nigerian man allegedly tried to blow up a trans-Atlantic jet on Christmas Day.

Spokesman Robert Gibbs said the president wanted to know how a man carrying dangerous substance PETN had managed to board a flight in Amsterdam.

He said the system of watch-lists would also be examined after it emerged the man was listed and known to officials.

A US record for 23-year-old Umar Farouk Abdulmutallab was created last month.

Mr Gibbs told ABC News that the review would examine, firstly, the system of watch-lists used by government agencies, which includes three lists which become progressively shorter as risk increases.

'Dangerous substance'

The lists include a watch-list, with some 550,000 names on it, a "selectee" list with 18,000 people within the higher-risk category, and a "no-fly" list with 4,000 names of people who are not permitted to board planes.

Mr Abdulmutallab was placed on the lowest-risk list by US authorities in November 2009, after his father alerted authorities about the behaviour of his son.

Mr Gibbs said the number of people on the watch-list was "a huge number".

"The president has asked that a review be undertaken to ensure that any information gets to where it needs to go, to the people making the decisions. The president wants to review some of these procedures and see if they need to be updated," he said.

On 24 December Mr Abdulmutallab travelled from Nigeria to Amsterdam and then on to Detroit with an explosive device attached to his body, US officials say.

Shortly before the flight was due to land in the US, he allegedly attempted to detonate the device beneath a blanket but he was overpowered by passengers and crew.

Mr Abdulmutallab, the son of a prominent Nigerian banker, has been charged by US authorities with trying to blow up the Northwest Airlines flight as it was coming in to land.

US airlines especially have tightened security after the attempt, increasing screenings and body searches and, in some cases, confining passengers to their seats without pillows or blankets for the last hour of their flight.

Mitigation measures

Mr Gibbs said "air detection capabilities" would also be examined as part of the review.

"The president has asked the Department of Homeland Security to answer the - quite frankly - the very real question about how somebody with something as dangerous as PETN could have gotten onto a plane in Amsterdam."

PETN, or pentaerythritol, is the same material used by convicted shoe bomber Richard Reid who tried to destroy a trans-Atlantic flight in 2001.

Mr Abdulmutallab's route originally began in Yemen, from where he travelled to Ethiopia, then to Ghana and finally Nigeria.

According to Nigeria's information minister, Mr Abdulmutallab had arrived and flown out of Nigeria in the space of a single day.

"The man in question has been living outside the country for a while," said Dora Akunyili.

"He sneaked into Nigeria on the 24th of December and left the same day."

Nigerian authorities, who on Sunday pledged to co-operate fully with the US investigation, said screening would be enforced for all passengers passing through the country's 22 airports.

Wealthy or influential people and their families are often allowed to skip checks, media reports say.

Speaking to ABC News, Homeland Security Secretary Janet Napolitano said there was no immediate indication that Mr Abdulmutallab was part of a broader terror plot.

"Right now we have no indication that it is part of anything larger. But obviously the investigation continues. And we have instituted more screening and what we call mitigation measures at airports," she said.

US condemns Taliban video of captive soldier

The US has condemned a Taliban video of an American soldier captured by the militants in Afghanistan last June as an affront to his family at Christmas.

The man in the film, identifying himself as Private Bowe Robert Bergdahl, criticises the US over the Afghan war and relations with Muslims.

A Taliban spokesman then calls for the release of captured insurgents in exchange for the 23-year-old.

His parents, Bob and Jani Bergdahl, responded by appealing for his release.

The Western military alliance Nato confirmed that the man in the video - seen wearing sunglasses, a military helmet and uniform - was Pte Bergdahl.

It said he had clearly been forced to read a prepared statement. It is not clear when the video, released on Friday, was recorded.

The airborne infantryman, originally from the US state of Idaho, spoke clearly and appeared healthy.

He was captured in Paktika province, a Taliban stronghold in eastern Afghanistan, on 30 June.

US Navy Rear Adm Gregory Smith said in a statement: "It reflects nothing more than the violent, deceitful tactics of the Taliban insurgency.

"To release this video on Christmas Day is an affront to the deeply concerned family and friends of Bowe Bergdahl."

The Bergdahl family later issued a statement through the Idaho National Guard, urging the captors "to let our only son come home".

And to Pte Bergdahl, the family said: "We love you and we believe in you. Stay strong."

'Next Vietnam'

In the video, Pte Bergdahl gives his rank, date and place of birth, and deployment details.

"This is just going to be the next Vietnam unless the American people stand up and stop all this nonsense," he says.

He adds: "You are not fighting a small group of terrorist guerrilla fighters.

"You are fighting an organised guerrilla army that has perfected guerrilla warfare better than any country has ever perfected it in history."

A statement read by a Taliban spokesman, Zabihullah Mujahid, appears at the end of the video and renews demands for a "limited number of prisoners" to be exchanged for Pte Bergdahl.

The insurgents also released a video of the American a few weeks after he was captured.

The Pentagon has said Pte Bergdahl was serving with an Alaska-based infantry regiment in Paktika province.

He vanished from his base, near the border with Pakistan, just five months after arriving in Afghanistan.

The military has been trying to locate him ever since, and a reward has been offered for his safe return.

He is believed to be the first soldier seized in either Iraq or Afghanistan for at least two years.

Worshippers gather to celebrate Christmas in Bethlehem

Thousands of Christian worshippers have celebrated Christmas Day in Bethlehem - believed to be the traditional birthplace of Jesus Christ.

Palestinians and pilgrims from around the world came together in the town to celebrate the event.

Hundreds attended morning mass at St Catherine's Church, in the Church of Nativity complex on Manger Square.

About 15,000 tourists are expected to stay in the town during the holiday period.

Rock music was played while traditional carol singers mingled with worshippers in the town.

Other celebrations took place at locations including at Saint George Orthodox Church in the West Bank village of Burqin near Jenin.

'Family gathering'

Some 300 Christians over the age of 35 from the Gaza Strip were given permission by the Israeli military to travel to Bethlehem and stay for 24 hours to celebrate Christmas.

About 80 people were also reported to have stayed and attended services at Gaza City's Roman Catholic Church.

Visitor Jonathan Croy from Alabama in the US said the feeling in Bethlehem was one of a "giant family gathering", the Associated Press (AP) news agency reported.

"It's interesting being here and seeing the dichotomy of religions, all nationalities and religions mixing together," he said.

The Vatican's envoy to the Holy Land, papal nuncio Antonio Franco told AP he was "hopeful" that peace was possible.

Earlier, during midnight Mass, Latin Patriarch Foud Twal, the most senior Roman Catholic cleric in the Holy Land, delivered his Christmas message to thousands of pilgrims in Bethlehem.

"The wish that we most want, we most hope for, is not coming - we want peace," he said after arriving in Bethlehem after the traditional holiday procession from nearby Jerusalem.

Christmas shoppers defy cold weather to spend

UK shoppers have defied the harsh winter weather to spend during the last weekend before the Christmas holidays.

The New West End Company, which represents more than 600 traders in central London, said sales were up 10% on last year's sluggish trading.

"We estimate £140m to be spent over the weekend and we are looking to go over a million people," it said.

Heavy snowfall has caused traffic chaos in many parts of the UK, and is expected to continue on Sunday.

Sales were reported to be brisk across the UK, while credit card firm Visa expects people to keep spending this week.

Visa expects to process a new record of more than 17 million transactions in the UK on 23 December, up 16% from the same day last year.

'Fed up'

"We think it's going to be significantly greater this year because people have bounced back from recession," said Richard Dickinson, chief executive of the New West End Company, which represents shops in Bond Street, Oxford Street and Regent Street.

"Either they are fed up with the recession and want to enjoy Christmas or they are thinking we are pulling out of it now."

The company said only 40% of goods were on sale this year, compared to 90% last year.

Customers were also buying more expensive items such as televisions, as they attempted to beat the increase in value-added tax, back to 17.5% from 15%, in the new year.

Bluewater Shopping Centre in Kent expects 250,000 shoppers over the weekend and said November sales rose by 5% compared with the same month last year.

"We have had a tremendous few months in the run-up to Christmas," a spokesman said.

Capital Shopping Centres, which represents 14 regional shopping centres including Braehead in Glasgow, Lakeside in Thurrock and Metrocentre in Gateshead, reported its busiest day of trading on Saturday.

The company said more than seven million shoppers had passed through the centres this week.

The Met Office said that "heavy and prolonged" snow showers would continue through the afternoon across Greater Manchester.

Dead soldier's Christmas message

The girlfriend of a British soldier who died trying to stop suicide bombers in Afghanistan received his Christmas card the day before his death.

L/Cpl David Kirkness, 24, from Morley, West Yorkshire, was one of two soldiers who sacrificed their lives to stop an attack on a packed marketplace.

Mel Maclean, 31, said the card included the lines "sorry aint going to be home with you all" and "love you babes".

She choked back tears as she told how she had last spoken to him on Sunday.

She received the Christmas card the next day.

Ms Maclean said L/Cpl Kirkness's mother had told her he was going to ask her to marry him during a family holiday planned for April next year.

She said his letters always talked about a surprise he had for her and she now knew that was a marriage proposal.

She said that felt "really special".

Ms Maclean added: "I knew if it came to somebody or himself, he'd save somebody else.

"He's a hero - there's no other word for him. We're all really proud of him."

L/Cpl Kirkness's father Chris agreed that his son was a hero.

He said: "It's what he does. He's always put other people first and it's what he's done again.

"I just want to remember him for what he's done.

"He's given his life to save a hell of a lot of people."