Carry on baggage: a screening mystery?

Baggage screening

After noticing an alarming drop in throughput in its domestic passengers security zones Zurich Airport conducted a detailed review of passenger behavior and carry on baggage screening to find out the cause. The results showed that liquids are no longer a problem but there has been a significant change in the contents of passenger bags due to cheaper fares being introduced by domestic carriers which are directly linked to baggage policy.

by Gary Mason

Following the terrorist attempts to blow up several aircraft during flight using homemade explosives carried inside soft drink bottles at London-Heathrow Airport in 2006, the European Commission and many other countries adopted additional rules on aviation security to address this newly-identified threat.

As every regular air traveller knows, these new rules restricted passengers on carrying liquids, aerosols and gels (LAGs) of a certain size past screening points, whether on their person or in their hand luggage.

This ban was envisaged as a temporary restriction to be lifted when suitable technology to screen liquids for explosives became readily available. But it is still very much with us and when first introduced, was a cause of heavier workloads and bottlenecks in police operated and outsourced security checkpoints at airports.

There is evidence that the threat from liquids aerosols and gels has receded into the background and a far more topical threat is emerging with electronic devices. This was highlighted last month by the sudden ban on lap tops and tablets inside the cabin on flights from some Middle Eastern airports imposed by both the UK and US.

These new threats are emerging at a time when authorities are still playing catch up with the need to upgrade existing screening technology to deal with historical threats. For example, all airports and airport operators need to comply with Hold Baggage Screening Standard 3, which comes into force in 2018. This framework, regulated by the ECAC (European Civil Aviation Conference), requires airports to achieve detection levels only provided by CAT (Computed Axial Tomography) type detectors.

The ECAC Common Process of Security Equipment applies to explosive detection systems (EDS), liquid explosive detection systems (LEDS) and security scanners. The Next Generation Standard 3 requirements are creating new challenges for busy airports impacting engineering, operations, budget, safety and security.

Standard 3 screening requires that the baggage handling system can guarantee complete tracking of all bags. If the screening decides that a bag is suspect and it needs to be recalled or re-routed for inspection, the system must be able to instantly trace where the bag is to deal with it speedily and effectively.

In a typical Standard 3 system, during screening, security operators have 60 seconds of variable decision time to determine the status of a bag without interfering with bag flow before the system clears the bag for the sorting system or sends a suspect bag for manual inspection.

The practicalities of upgrading hold baggage screening equipment can cause immense pressure on airport operators and their stakeholders. The effect of such disruption, and the outcome of such changes on airport capacity and passenger flow through terminals is yet to be fully felt as the 2018 deadline approaches.

But this also impacts on the police and security personnel charged with making sure the screening process is both thorough and not leading to bottlenecks and huge queues of disgruntled passengers during peak periods.

Zurich Airport has conducted a study on baggage screening technology and processes and passenger behavior after noticing an alarming drop in throughput in their security control areas over the last four years.

Security staff at Zurich process 28 million passengers who come through the airport each year and passenger numbers have been rising steadily. At the same time, as is the trend with other airports, hold baggage has been decreasing, given that many airlines now charge up to €50 for each additional bag brought on to the aircraft but stored in the hold.

Pawel Kolatorski is a senior project leader at Zurich Airport. He points out that new products from airlines encourage passengers to put all their belongings into their carry on baggage. This is in addition to other changes in passenger behaviour over the last 20 years which has increased the complexity of carry on baggage content and its impact on the security process.

In 2016 the airport noticed a 10 per cent drop in passenger throughput through the 46 checkpoints it operates. Was this down to passengers bringing more LAGs in their on board bags or was it due to other types of suspect items being screened and rejected by the police operators?

As a consequence of this significant drop in throughput the airport conducted a major study of passenger behavior with regard to carry on baggage and how that impacts on the security screening process. “The main focus was the passenger at security control,” he says. “The findings cover the baggage in terms of the amount, the changing content and the ergonomics of the security control as well as the workload.”

A significant aspect of the research focused on domestic passengers – approximately 10 million from Zurich each year. There are 26 security checkpoints that deal with this domestic traffic.

“As we started 2016 we noticed a massive drop in the throughput by more than 10 per cent,” he says. “We knew that 2016 would see a significant growth in passenger numbers so we were a little worried about the effect that would have on throughput which was already declining.

“We know that the security process itself is a complex system – mostly when there are problems with a reduction in throughput it is not caused by a single factor but multiple factors that together impact upon the process.”

So the airport decided to expand their review to not just include the security process itself but the services and products provided by domestic carriers and how this had impacted on the working environment of staff at security control.

The first thing the airport noticed was the general reduction in the amount of baggage being carried by domestic passengers. Most remarkable of all was a massive drop in the third quarter of 2015 of between 5 and 7 per cent in the amount of baggage per domestic passenger coming through the airport. However, this downward spike was not a major surprise as it coincided with the airport’s main domestic carrier – which flies 60 per cent of passengers coming through the airport – introducing a new “light fare.” This is the lowest price offered to passengers who agree to travel without hold baggage.

“So we knew we would see this big drop in hold baggage around that time,” says Kolatorski. “But the question was where has that volume gone given that our throughput numbers were significantly down? Was it in the carry on baggage or did the passenger really change their behavior due to the price?”

In order to find out the answer to this question the researchers decided to take a forensic look at the security process – specifically focusing on the IPPs (images per passenger in terms of the screening of baggage at the security control checkpoints.)

Analysis of the IPPs for the last three years showed no change at all in the downward trend. “We could actually see that the passengers were taking less with them because there were less pictures per passenger,” he says. “So the throughput should have gone up but unfortunately that was not the case.”

He said that a lot of people had argued that the introduction of light fares by the airport’s biggest domestic carrier had to be the main reason for the throughput drop. But none of the statistical evidence on the screening process backed this up.

There was also a theory that all the liquids aerosols and gels (LAGs) that passengers used to take in their hold baggage was now being placed in the carry on baggage and this is what was causing the drag on throughput.

Again the statistical evidence fails to back this up. “The only way we could analyse this was by tracking our disposed LAGs waste,” says Kolatorski. Disposed LAGs in terms of weight was averaging daily at around 600kgs. This is the amount of LAGs taken from passengers’ on board baggage by security staff who intercept in the screening process.

But despite the increase in the numbers of passengers using the airport there was no change in LAGs waste between 2012 and 2014. And after the predicted increase in 2015 it dropped again in 2016. “Once again, when the amount of LAGs waste is dropping we should expect a higher throughput because there is less for security staff to do,” he adds.

Dr Signe Waechter Ghelfi, a psychologist with Zurich Airport Police led the research. She says that if anything the research shows that passengers are bringing less liquids aerosols and gels with them through the checkpoints but there is evidence that on board baggage is being packed more densely and screeners are finding it more difficult to “clarify” potentially dangerous objects that are in the on board bags.

The trial involved a random sample of items that would be regularly carried in hand luggage in 2008 after the liquids ban and more recent items from 2016. The researchers measured the police screeners’ reaction times in clarifying the objects. They found that many were taking up to 15 times longer to screen the modern bags.

“There are two significant findings in the research,” she says. “One is that the more densely packed bags contain more electronic items that are more difficult to screen.”

She says that the second finding is evidence that screeners may be applying “rational cognitive shortcuts” in screening what they think are familiar items carried in hand luggage. “This could pose a potentially significant security risk because screeners are making snap judgements quicker and could be screening items less thoroughly than they require,” she says.

Although the research was a snapshot sample she says it may have useful applications to additional cognitive training and decision making for screeners.

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