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A quiet revolution is underway in how we transit airport security -- but most of us won't even have noticed.

The requirement to put liquids into 100-millilitre containers and take electronics out of bags has been a staple of air travel for nearly 16 years. However, at many airports around the world new technology is already in place that will allow that rule to be scrapped, and some are now beginning to drop the ban.

Back in October 2021, Shannon Airport, in the west of Ireland, quietly announced its new state-of-the-art computed tomography, or CT, scanning security system, installed at a cost of €2.5 million (about US$2.6 million).

Liquids and electronics could now remain in bags, with no restrictions on liquid volume, and cabin bags could be whisked through the scans in new larger trays.

It's not the first time Shannon, Europe's most westerly airport, was a global pioneer. The world's first Duty-Free shop opened here in 1947, and in 2009 it became the first airport in the world, outside of the Americas, to provide full U.S. pre-clearance facilities.

"It is one of the projects Shannon Group took on during the period of severe travel restrictions on aviation," Nandi O'Sullivan, the group's head of communications, tells CNN Travel.

Implemented during the pandemic, it was only when international travel resumed in March 2022 that the airport's move started to gain wider attention. Donegal Airport, in the northwest of Ireland, has also followed suit by installing new technology and dropping the 100-millilitre rule.

BETTER SECURITY, SHORTER LINES

So how does this new CT technology work, which airports are already using it, and why aren't more places relaxing their restrictions?

Kevin Riordan, head of checkpoint solutions at Smiths Detection, the company that provides Shannon's security equipment and a global leader in computed tomography technology, explains.

Just as with the CT scans we know from hospitals, the security scanners at airports replace conventional 2D X-ray scanning with much more precise 3D imaging.

"You can get a lot of information from a 2D image but if you've got a 3D object in your hand you get a lot more information," says Riordan.

"From a security point of view, they're able to make very accurate decisions about what the materials are in your bag: Is it a likely threat material or is it benign. That's better security, better decisions."

Shannon Airport estimates that time spent going through its passenger security screening will be halved by the new technology, and unsurprisingly, Riordan says that passenger feedback has been very positive at airports where the new machines have been trialled.

The liquid ban was introduced around the world after a transatlantic terrorist plot was foiled in August 2006, in which a group planned to detonate liquid explosives on board multiple flights. It's become part of daily life, but many of us fondly remember the times when security lines were faster and luggage-packing was simpler.

GRADUAL ROLLOUT

CT technology first began to make headlines back in 2018. The scanners were trialled at major airports including London Heathrow, New York JFK and Amsterdam's Schiphol. The following year, Heathrow announced that it was investing £50 million (about $62 million) in a gradual rollout of the technology across its airports with a deadline of 2022.

In July 2020, it was announced that London Southend Airport would become the first in Britain to drop the practice of making passengers take their liquids and electronics out of the bags before going through security.

Amsterstam Schiphol has also been using CT technology at all its checkpoints since 2020, Dennis Muller, senior spokesperson for the airport, tells CNN. But unlike Southend or Donegal, it's a major international hub. It's no longer mandatory for its passengers to follow liquid restrictions, but the airport advises that they use 100-milliliter containers all the same, to avoid problems when flying to other jurisdictions.

"The Netherlands has moved quicker, probably, than most," says Riordan. "The U.K. has actually mandated that technology by 2024, and that would allow all restrictions about what you can carry on to be lifted."

Once more countries are able to complete full nationwide rollouts of the technology, we will start to see more airport and regions start to see the ban being lifted or relaxed -- but changes to regulations will not come fast or universally, and it's a changing landscape.

STAFFING CONSTRAINTS

"It's a dynamic picture that we're still trying to understand, what has the impact been over the last two years," says Riordan. "Passenger numbers are recovering in many airports (probably) quicker than expected." There have been widely reported staff shortages at airports and on airlines around the world, leading many to predict a ahead.

Smiths Detection is one of a small handful of companies in the CT technology field, with U.S. company Leidos being a principal competitor -- last year it was awarded a to deploy checkpoint screening technology in the States.

"It's a continuing process for us as suppliers," says Riordan. The current staffing constraints "puts pressure on us to design operations that are much more efficient. CT technology is the best available, but is there a smart way of using it, to optimize it?"

One innovation is multiplexing: "You put a stream of bags through a machine and the images are sent to (three or four) different operators, not just one operator per machine. That's one way of trying to compensate for this lag in staff and increase in passengers."

BUSINESS CASE

The cost of implementing this new technology isn't cheap, and smaller airports, already struggling post-COVID, may find upgrades a challenge.

Each will have their own scheduled cycle of upgrades and innovations to consider -- covering all the many constraints and demands of a 21st-century hub.

When nations mandate the upgrade, more airports will be under pressure, but until that time, on an individual airport level, it's about the business case. Efficiency and customer satisfaction is of course of paramount importance, but shorter security lines means also passengers getting airside quicker -- and spending more money in airport shops and restaurants. "It's different in different global regions. it'll happen at different speeds," says Riordan.

It's too early to predict how fast things will progress, but with airports like Shannon and Schiphol leading the way, we could see developments in next the few years -- and with the industry recovering, it'll likely be sooner rather than later.

CNN reached out to Heathrow for comment for this story.