Chaos at Birmingham Airport over 100ml liquid limit: What can you bring in your hand luggage?

The UK's Birmingham Airport saw major delays this weekend amid confusion over new rules about liquids in hand luggage.

Photos on social media showed queues that stretched outside of the airport from as early as 5am. Some passengers said they had to wait up to two hours to pass through security.

This travel chaos comes less than a week after new restrictions were introduced for liquids in hand luggage. Several UK airports had planned to increase the limit from 100ml to two litres with the introduction of a new scanning system.

But the installation of this system has been delayed, the 100ml rule is still in place and passengers have been left confused about what they are allowed to bring in their hand luggage.

Why has there been confusion in the UK over liquid rules?

The UK government originally gave a handful of airports approval to up the limit on liquids passengers can carry to two litres following the installation of new CT scanners.

It would have meant that from 1 June, the 100ml liquid limit would not have been in place at these airports. But many, including Heathrow, Gatwick and Manchester, missed the mark with installing new scanners due to logistical errors.

Others which had met the deadline had already lifted the 100ml liquid rule.

Now the UK's Department for Transport has said that the ban will be temporarily reintroduced at six airports: London City, Aberdeen, Newcastle, Leeds/Bradford, Southend and Teesside.

Airports say the sudden u-turn has left many passengers confused about what they can bring in their hand luggage during one of the busiest periods of the year.

Trade organisation the Airport Operators Association (AOA) said the latest changes had been "instigated with very little notice".

"It has also put airport operators in a challenging position, with very limited time to prepare for the additional staffing and wider resources that this will require, and no clear idea of when this issue will be resolved," chief executive Karen Dee said in a statement.

Birmingham Airport is one of the travel hubs that had upgraded to the new scanners but has had to keep the 100ml rule in place.

It said it has been limited on the use of its new high tech equipment due to an "outstanding regulatory restriction" which has meant limiting liquids to 100ml. Passengers can still keep their liquids inside of their bags while going through security, however.

"Despite the 100ml rule still being in place, we continually have non-compliant bags with liquids over the allowance which have led to inefficiencies of our equipment and resulted in extended queuing time for customers," it said in a statement.

The airport added that a non-compliant bag with liquids over the 100ml limit can add up to 20 minutes to each passenger's journey through security.

Why is the 100 ml liquid rule in place at airports?

Since 2006, airline passengers around the world have been limited to carrying liquids no larger than 100 ml in their hand luggage.

The rule was introduced after British police uncovered a terrorist plot to detonate liquid explosives disguised as soft drinks on a series of transatlantic flights.

The conspirators intended to assemble and detonate a device mid-flight, with hydrogen peroxide and other substances injected into 500 ml soda bottles, leaving the caps sealed. If mixed to a specific strength with other ingredients, the common bleach product can become explosive.

If the plot had been successful, it is believed it would have been far more deadly than the 9/11 attacks. It would have targeted multiple flights heading from the UK to at least five US and two Canadian airports.

Immediately after the discovery, hand luggage was completely banned on planes as a precautionary measure. This was later relaxed after tests were carried out to determine what amount of liquid was safe to carry, and a 100 ml container limit was introduced.

Experts found that mixing the smaller containers into a larger one to create a highly damaging explosive device on board was not realistic. They determined this would either fail or prematurely detonate, injuring the perpetrator but doing little to no damage to the aircraft.

Passengers are now limited to taking a maximum of one litre of liquids through security in containers no larger than 100 ml each. These must be separated into a clear resealable bag and removed from hand luggage when passing through the security scanners.

Why is the 100 ml liquid rule ending?

After 18 years, the 100 ml liquid rule will soon be ditched in some countries thanks to advanced new security scanners.

Using Computed Tomography (CT) X-ray technology, similar to that used in the medical field, they provide a clear 3D image of what’s inside passengers’ bags.

The images can be rotated 360 degrees and zoomed in on, allowing thorough analysis that’s likened to ‘digitally unpacking the bag’, device manufacturer Smiths Detection explains. This is an improvement on the current 2D imaging used at most airports.

The scanners also deploy sophisticated threat detection algorithms that can detect explosives - including liquids - and other hazards, according to the UK’s Department for Transport.

Existing 2D scanners can discriminate between organic and inorganic materials, displaying items in different colours, but CT scanners take this a step further.

With the help of AI technology, they can differentiate liquids - such as water, hydrogen peroxide, or high-strength alcohol - and offer a more complete view of electronics, according to equipment manufacturer Sens-Tech.

"The newest screening technology that is being deployed can detect explosive compounds in larger quantities," a US Transportation Security Administration (TSA) spokesperson further explains.

If an item appears suspect, the bag will face further screening by security officers, who will inspect it for prohibited items. The new scanners promise fewer false alarms, hopefully meaning a reduction in unnecessary bag checks.

Will removing the 100 ml liquid rule make flying less safe?

Removing the 100 ml liquid rule will not make flying less safe. On the contrary, the new scanners will improve security, according to the UK’s Department for Transport.

This is because they provide more detailed images of what people are carrying, allowing them to detect potential threats and prohibited items with greater ease.

It will also streamline the airport experience, cutting security check times and making travel more convenient for passengers.

An added benefit is the reduction of plastic waste, as passengers abandon using dozens of disposable toiletry bottles in favour of larger containers.

The new tech could also save passengers money, as they will be allowed to bring in water and other drinks from outside, rather than relying on expensive airport shops.

When will the 100 ml liquid rule be removed in Europe?

Some European airports have already installed the new CT scanners.

Terminal 1 at Italy's Rome Fiumicino airport has had the scanners since March. Terminal 1 at Milano Linate and Milano Malpensa have had them since February.

In Spain, new airport security rules came into force on 1 February 2024, but many airports are yet to install the updated hand luggage scanners. It is expected to be implemented progressively over the coming months and years.

Barcelona's El Prat and Madrid Barajas airport say they hope to start rolling out the new system in summer 2024. Malaga has plans to introduce the system from 2025 and Gran Canaria, Tenerife South, Fuerteventura, Lanzarote, Alicante, Ibiza, Bilbao, Menorca and Valencia from 2026.

Munich airport in Germany has been being gradually converted since the beginning of the year and should be finished in 2025. Frankfurt has fast lanes that use the scanners in some terminals with more to be added by the end of the year.

Even if an airport has brought in new scanners, it doesn't automatically mean you can take larger liquids with you. Once the machines have been installed, the 100 ml rule will be phased out over the following two years and its worth checking the website of airport you are travelling through to avoid confusion or delays.

Until then, passengers may not experience the time-saving benefit of the new tech. But ultimately, the simplified system could help airports process 30 per cent more passengers per hour, according to Sens-Tech.

Do airports outside of Europe have CT scanners?

Even when the new measures are in place, passengers are advised to check the rules for countries they are transiting through or travelling back from, as many destinations are yet to implement this new technology.

If 3D scanners are not installed in the airport you are returning from, you could be forced to throw away liquids over 100 ml in your hand luggage.

Only a handful of European airports have plans to install 3D scanners. Elsewhere, some US airports like Atlanta's Hartsfield-Jackson, Chicago O'Hare and New York’s LaGuardia have started using the new tech.

However, TSA says it will take many years to deploy the technology across the entire system in the US, meaning the 100 ml rule (known there as 3-1-1) will remain in place to ensure transportation is secure.

Qatar's Hamad International Airport in Doha has also stepped up its security with the new scanners.

How do 3D airport scanners impact electrical items?

Tablets and laptops must currently be removed from cabin baggage before passing through the security scanners at most airports.

CT scanners will eliminate the need for this, as they allow electrical items to be studied in detail while still inside a bag.

Film camera enthusiasts have noted that increased radiation emitted by the new scanners could damage analogue film, leading to fogging and colour degradation. Some Reddit users say they ask for their film to be examined by hand, though this is at the discretion of airport staff.