In short: The new airport scanners (CT machines that let passengers leave liquids and laptops in their bags) are cabled into fibre, but the queue sensors, supervisor tablets, temporary lanes and tray systems that decide how fast a security hall actually moves mostly depend on a wireless network that was never designed for them. Airports that plan that network alongside the scanner programme get the throughput they paid for.
Key Takeaways
- The CT lane is wired, the hall around it is not — scanner images travel over fibre, but queue sensors, supervisor tablets and lane-status displays sit on whatever wireless the terminal already has.
- Rebuilds run on temporary lanes — CT scanners are heavy enough to need floor work, so halls are rebuilt a few lanes at a time and the temporary lanes need connectivity within days, not months.
- Queue data only helps if it arrives in time — a five-minute queue standard is managed minute by minute, which needs sensors and staff devices on a network that stays up when the terminal is full.
In a nutshell
What are the new airport scanners, and why did they take so long?
The new airport scanners are computed tomography (CT) machines, the same principle as a hospital scanner, which build a 3D image of each bag so that a screener can rotate it, slice through it and let automated detection software look for explosives. Because the machine can see through a packed bag, passengers no longer need to take liquids, gels and laptops out at the lane. That is the change travellers notice, and it is why "new airport scanners" is searched far more often than any of the technical terms behind it.
The UK rollout has been slow and public. The 100ml liquids rule arrived in 2006, after the transatlantic airliner plot. In December 2022 the government told the larger UK airports to install CT scanners by June 2024. Most missed that date and received extensions, and in June 2024 the Department for Transport temporarily reinstated the 100ml limit even at airports that had finished their installations, pending further work on the equipment's certification. Birmingham and Edinburgh became the first large UK airports to move to a two-litre allowance in summer 2025, and other airports have followed lane by lane since.
Much of the delay came from the buildings. A CT unit is longer and considerably heavier than the X-ray machine it replaces, so floors have needed strengthening, power and cooling have needed upgrading, and security halls laid out in the 1990s have had to be reconfigured around new lane lengths and automated tray return systems. Every one of those projects has been planned around the scanner. Very few have been planned around the wireless network the rest of the hall now depends on.
Do the new scanners mean shorter security queues?
Not automatically. The scanner removes the divesting step, which is where a lot of time used to go, but the throughput of a security hall is set by the slowest part of the whole process: how many lanes are open, how many staff are on them, how fast trays return, how many bags are pulled for a manual search, and how quickly a supervisor notices that one lane is backing up while the next is idle.
Some of those factors get worse before they get better. A 3D image takes longer to review than a 2D one until screeners are practised with it, and detection software tuned conservatively in the early months sends more bags to the reject belt. Airports that expected the new airport scanners to cut queues on day one have, in several cases, found that the queue simply moved: from the divest benches to the search tables, or from security back into the check-in hall.
Managing that is an operational job that runs on live data. At Heathrow, the Civil Aviation Authority's service quality regime measures central search queues against a five-minute standard and attaches financial rebates to failure, so the airport has a direct commercial reason to know, minute by minute, how long people are waiting. Manchester's queues of summer 2022, which ran out of the terminal buildings and into the car parks, were a staffing failure rather than an equipment one, but they showed how fast a hall tips over when nobody can see it coming.
What runs on the network around a security lane?
The CT lane itself is a wired system. The scanner, its image processing and the screener's workstation sit on a dedicated fibre network, and in the larger airports images can be routed to a centralised review room away from the lane. That is correct and we would not change it; scanner images are large, latency-sensitive and security-critical, and nobody should be carrying them over radio.
Around the lane, the picture is different. A typical CT security hall now has:
- overhead 3D queue sensors (Xovis is a common supplier) counting passengers and estimating wait times at the hall entrance, the lane entry points and the reject area;
- supervisor tablets and screener handhelds showing lane status, staff allocation and breaks;
- queue-time displays landside and in the airport app, fed from the sensor data;
- automated tray return systems with their own controllers and fault reporting;
- boarding-pass gates and fast-track lanes, which need to reconcile against departure data;
- radios and phones for the security team, the duty manager and the police.
Some of this is cabled. A great deal of it is not, particularly anything carried by a person or installed after the hall was built, and it ends up on the terminal's Wi-Fi, often the same unlicensed spectrum carrying thousands of passenger phones. We have written before about why airport Wi-Fi buckles under peak load; the security hall is where that matters most, because the moment the terminal is busiest is the moment the queue data and the supervisor's tablet are most needed.
Why do temporary security lanes cause connectivity problems?
Because they are built faster than the network is. Rebuilding a security hall for CT scanners is usually done in phases: close two or three lanes, strip them out, strengthen the floor, install the new kit, commission it, and repeat, while the airport keeps passengers moving through whatever lanes remain. That often means temporary lanes in places that were never meant to hold them: a former retail unit, a corridor, a section of the check-in hall.
Each temporary lane needs the same supporting systems as a permanent one. The queue sensors, the boarding-pass gate, the supervisor's tablet and the lane-status display all need connectivity on the day the lane opens, and the cable routes, comms rooms and access points that serve the permanent hall are rarely in the right place. Airports have filled the gap with long temporary cable runs, extra Wi-Fi access points and 4G routers, which works, but each phase repeats the exercise and each workaround becomes something the IT team has to support.
Interestingly, the rebuild programmes are long. A large terminal can take several years to convert every lane, and many UK airports are now pairing CT works with wider terminal reconfiguration, so the temporary state is the normal state for a good part of the decade.
Where does private 5G fit in an airport security hall?
A private 5G network is a mobile network that belongs to the airport, on licensed spectrum from Ofcom's shared access bands, with SIMs issued only to the airport's own devices. In a security hall it does three jobs that are awkward for Wi-Fi.
Firstly, it separates operational traffic from passenger traffic. Queue sensors, supervisor tablets and lane displays run on spectrum that passenger phones cannot use, so a full departure lounge does not degrade the data the duty manager is relying on.
Secondly, it handles moving lanes well. One or two small cells mounted high in a security hall can cover the whole floor plate, including the corners where temporary lanes end up. A new temporary lane needs power and a device with a SIM, rather than a new cable run back to a comms room, and when the lane moves again the network does not have to.
Thirdly, it gives the security team a common network across the hall, the reject area, the staff search and the airside exit, so a supervisor's tablet or a screener's handheld behaves the same wherever they are standing. That is a modest-sounding benefit until a supervisor walks twenty metres to the search tables and loses the lane-status view on a busy Friday morning.
There are trade-offs. Private 5G needs devices with 5G modems, and a lot of the existing estate (older queue sensors, some tray system controllers) is Wi-Fi or wired only, so in practice it sits alongside Wi-Fi rather than replacing it. It needs an Ofcom shared access licence and someone to run the core, which is why most airports buy it as a managed service. And it is not for the scanners themselves, which belong on fibre. Where an airport has a well-designed, lightly loaded operational Wi-Fi network that already covers the hall, the case is weaker; where the hall shares Wi-Fi with passengers and is being rebuilt in phases, it is strong.
What should an airport plan before its next security hall phase?
The cheapest time to fix the network is during the scanner works, when the ceiling is already open. We would suggest an airport's estates and security teams do four things together before the next phase starts:
- List every device in the hall that is not on the scanner fibre, including those on temporary lanes, and note which network each one uses today.
- Measure the hall at peak, ideally on a busy summer Friday, to see how much passenger traffic shares the same channels as the operational devices.
- Map the temporary lane positions for the whole programme, not just the next phase, and plan coverage that reaches all of them.
- Decide which systems need to be on licensed spectrum (supervisor devices, queue data, lane status) and which can stay on Wi-Fi.
Regional airports should do this too. Several of them converted to CT early, on smaller budgets and with fewer lanes, which means a single lane failing or a single queue sensor going dark has a proportionally larger effect on the hall. A one-cell private 5G network covering a regional security hall is a small piece of infrastructure, typically installable during an overnight closure, and it can be extended airside to stands and baggage areas later.
The new airport scanners have been bought, installed and, in most cases, paid for. The next gains in queue times will come from the people and data around the lanes, and the first step is a peak-hour survey of the security hall before the next phase of works is signed off.