Passengers at British airports have faced travel chaos on multiple occasions over the last few weeks, from heavy winds to fog.

Now, the Met Office has issued an amber warning for snow and ice in the Midlands, north of England and Wales, which says that delays and cancellations to air travel are “expected”.

It can seem a mystery to many frustrated flyers that a brief spell of bad weather can upend schedules, especially since British weather isn’t exactly famed for being the best.

So why, with all the technological advancements of planes and airports in recent years, do flights get affected so badly?

While planes are designed to deal with the likes of snow and ice, fog and high winds, air traffic control often imposes strict safety limits in these situations.

As a result, “airports go into a kind of slow motion” with the spacing between arriving and departing aircraft increased, says travel expert Simon Calder.

If the conditions “require air-traffic controllers to increase the spacing between aircraft by 50%, capacity is immediately reduced by one third – and cancellations begin,” he adds.

There’s little slack in the system, as when things are running smoothly, schedules at London Heathrow – Europe’s busiest airport – are based on landing aircraft as close as 80 seconds apart. And London Gatwick, the UK’s second busiest airport, can facilitate a take-off or landing every 65 seconds.

The spacing between arriving and departing aircraft was increased at London Gatwick last weekend during the fog, which Mr Calder estimates led to about 75,000 passengers being affected.

Among them were James and Madison King, whose flight from Stockholm to London took a lengthy diversion because of the fog-related spacing limits.

They were within touching distance of home when the pilot announced they did not have enough fuel for a 50-minute holding pattern at Gatwick, so the plane diverted to Dublin to refuel. Flight crew shift limits then meant all the passengers had to fly back to where they started in the Swedish capital.

James says he still hasn’t been reimbursed for the £200 he spent on a hotel and dinner during this impromptu additional overnight stay in Stockholm.

Heathrow also saw delays and cancellations during high winds before Christmas.

Despite some airports trialling artificial intelligence to help planes land in low visibility, controllers in on-the-ground towers still need to clearly see an aircraft arriving before issuing a landing clearance, aviation expert Scott Bateman MBE wrote on X.

He says the majority of modern aircraft can automatically land in the worst fog, but that in practice visibility limits are imposed so pilots can see sufficiently to taxi off the runway.

Elif Arjin Celik’s flight from London Gatwick to Istanbul was delayed for hours because of poor visibility in the fog on 28 December 2024.

She saw thousands of people waiting in the terminal with nowhere to sit, and says it was “grim” having to wait 20 minutes to use the toilet because of the “extreme overcrowding”.

With upcoming warnings of snow, Mr Calder advises passengers to brace for more disruption to their flights because of spacing limits and runway closures.

“The UK has seen some shocking snow closures, where big airports have simply not been able to cope,” he says, citing an incident in 2010 where hundreds of thousands of passengers saw cancellations at Heathrow because of snow.

Snow also caused Manchester Airport to close both its runways in December 2022 and again in January 2023, with flights diverted as far away as Dublin and Paris.

Although the extreme cost of disruption on this scale has led to British airports investing more in hardware and training to clear snow quicker, don’t expect us to cope like airports in places such as Iceland and Greenland.

Mr Calder says we might never be as good as other countries at keeping an efficient schedule in unusual weather.

“Historically the UK has had a benign climate,” he says. “Spending millions preparing for an unlikely event has been hard to justify.”

There’s not great news on the horizon because in the future, we can expect more disruption from weather related to climate change, says Dr Ella Gilbert, a climate expert from the British Antarctic Survey.

“Aviation tends to be most impacted by extreme precipitation and stormy weather that makes flying unsafe – two weather types that are enhanced by higher temperatures,” she says.

She adds that climate heating increases the frequency and intensity of rain and snowfall events, making storms “stronger and more frequent” and increasing the frequency of aircraft turbulence.

Nats, the national air traffic service, is allowed to take action to reduce the amount of planes in the sky and space them apart more during adverse weather under the Transport Act 2000.

Given this is part of Nats’ obligation to prioritise safety over all other factors, it doesn’t have to compensate airlines for these restrictions – which in turn means airlines don’t need to compensate passengers for the resulting delays either.

The organisation told the BBC that it recognises there’s a tough balancing act.

“Flow regulations are only ever employed when absolutely necessary and have to be expertly timed,” a Nats spokesperson said.

“Unexpected additional or delayed air traffic can increase the pressure on controllers, particularly when the weather clears.

“If restrictions are lifted too early, they can risk an overpopulated airspace, while on the flip side, restrictions remaining in place longer than they need to can lead to unnecessary delays, which no one wants.”

This is brought into sharp focus during storms, Nats explained.

“Fundamentally, pilots don’t want to fly through storms,” it told the BBC.

“Although aircraft are robust, storms can still affect aircraft systems and excessive winds within unstable storm clouds make it much more difficult for aircraft to maintain their levels. It also increases turbulence, which negatively impacts passenger comfort.”

This leads to planes being in unexpected parts of the sky at different times, and all these new routes needing to be recalibrated to avoid any collisions.

Nats says it does have measures to mitigate disruption, including specialist Met Office weather equipment which can help foresee the need for safety limits to be imposed, while pilots also have more tech on board to help them fly around bad weather patches and inform air traffic controllers of potential issues.

When flights are delayed or cancelled to or from a UK or EU airport, airlines have a duty to look after you, including:

• Providing meals and accommodation, if necessary, and getting you to your destination. The airline should organise putting you on an alternative flight, at no extra cost
• Your airline must let you choose between either getting a refund or being booked on to an alternative flight
• For short-haul flights, the threshold for compensation kicks in after a three hour delay – but is only payable if the delay is deemed within the airline’s control, meaning you won’t be entitled to it if your plane is held up by fog, a snow storm or security incident.

Read more here.