London's Heathrow slowly resumes flights after a fire cut power to Europe's busiest airport

LONDON (AP) — A fire at an electrical substation knocked out power to Heathrow Airport for most of Friday, forcing Europe's busiest hub to shut down for roughly 18 hours, causing widespread cancellations and rerouting headaches, and stranding roughly 200,000 passengers.

The blaze started just before midnight on Thursday at a substation about 2 miles (3.2 kilometers) from the airport and took firefighters around seven hours to bring under control. Authorities said they found no evidence that it was suspicious, and the London Fire Brigade said its investigation would focus on the electrical distribution equipment at the substation.

The fire knocked out power to Heathrow and thousands of homes in the area. It affected at least 1,350 flights to and from the airport, according to flight tracking service FlightRadar 24, and the impact was expected to last several days, as passengers try to reschedule their trips and airlines work to reposition their planes and crews.

After power was restored, a British Airways jet touched down just before sunset on Friday after Heathrow lifted its closure order. Further arrivals followed, including a short flight from Manchester in northwest England.

A British Airways flight to Riyadh, Saudi Arabia departed from Heathrow just before 9 p.m. (2100GMT). British Airways says it will run eight long-haul flights on Friday night. The airport plans to operate full schedule on Saturday.

Residents in west London described hearing a large explosion, followed by a fireball and clouds of smoke, when the blaze ripped through the substation.

About 120 flights were in the air when the closure was announced. Some turned around and others were diverted to Gatwick Airport outside London, Charles de Gaulle Airport near Paris or Ireland’s Shannon Airport, tracking services showed.

Lawrence Hayes was most of the way to London from New York when Virgin Atlantic announced the plane was being diverted to Glasgow.

“It was a red-eye flight and I’d already had a full day, so I don’t even know how long I’ve been up for,” Hayes told the BBC as he was getting off the plane in Scotland. "Luckily I managed to get hold of my wife and she’s kindly booked me a train ticket to get back to Euston (station in London), but it’s going to be an incredibly long day.”

Heathrow is one of the world’s busiest airports for international travel, and saw 83.9 million passengers last year.

Friday's disruption was one of the most serious since the 2010 eruption of Iceland’s Eyjafjallajokull volcano, which spewed clouds of ash into the atmosphere and shut Europe's airspace for days.

It's too early to know for sure what sparked the blaze, but the Metropolitan Police force said counterterrorism detectives were leading the investigation because of their ability to find the cause quickly and because of the location of the electrical substation fire and its impact on critical national infrastructure.

The force said that "after initial assessment, we are not treating this incident as suspicious."

Heathrow said its backup power supply designed for emergencies worked as expected, but it wasn't enough to run the whole airport. It said it had no choice but to close the airport for most of the day.

The airport's CEO, Thomas Woldbye, rejected suggestions that Heathrow didn't have adequate contingency plans, saying the incident was “unprecedented.

"Contingencies of certain sizes we cannot guard ourselves against 100% and this is one of them," he said.

Nevertheless, the fallout from the fire led to criticism that Britain is ill-prepared to deal with disasters.

“The U.K.’s critical national infrastructure is not sufficiently hardened for anywhere near the level it would need to be at to give us confidence this won’t happen again,” said Alan Mendoza, the executive director of the Henry Jackson Society, a security think tank.

Tom Wells, a spokesperson for Prime Minister Keir Starmer, acknowledged that authorities had questions to answer and said a rigorous investigation was needed to make sure “this scale of disruption does not happen again.”

Heathrow originally said it expected to reopen just before midnight Friday, though with “significant disruption over the coming days."

Even after flights resume, it will take several days to mobilize planes, cargo carriers, and crews and rebook passengers, said aviation consultant Anita Mendiratta.

“It’s not only about resuming with tomorrow’s flights, it’s the backlog and the implications that have taken place,” she said.

Mark Doherty and his wife were halfway across the Atlantic when the inflight map showed their flight from New York’s John F. Kennedy Airport to Heathrow was turning around.

“I was like, you’re joking,” Doherty said before the pilot told passengers they were heading back to New York.

Doherty called the situation “typical England — got no back-up plan for something happens like this. There’s no contingency plan.”

At Heathrow, a family of five traveling to Dallas showed up in the hopes their flight home — still listed as delayed — would take off.

But when Andrea Sri brought her brother, sister-in-law and their three children to the airport, they were told by police that there would be no flight.

“It was a waste of time. Very confusing,” said Sri, who lives in London. “We tried to get in touch with British Airways, but they don’t open their telephone line until 8 a.m.”

Travelers who were diverted to other cities found themselves trying to book travel onward to London. Qantas airlines sent flights from Singapore and Perth, Australia, to Paris, where it said it would bus people to London, a process likely to also include a train shuttle beneath the English Channel.

Matthew Muirhead was working Thursday night near Heathrow when he stepped outside with a colleague and noticed smoke rising from an electrical substation and heard sirens.

“We saw a bright flash of white, and all the lights in town went out,” he said.

The London Fire Brigade sent 10 engines and around 70 firefighters to control the blaze and about 150 people were evacuated from their homes near the power station.

The blaze knocked out power to 67,000 customers, though most of it was restored by daybreak, the fire brigade said.

Flights normally begin landing and taking off at Heathrow at 6 a.m. due to nighttime flying restrictions. But the skies were silent Friday morning.

“Living near Heathrow is noisy, there are planes every 90 seconds or so, plus the constant hum of traffic, but you get used to it, to the point of no longer noticing,” said James Henderson, who has lived next to the airport for more than 20 years. “Today is different, you can hear the birds singing.”

Associated Press reporters Stefanie Dazio in Berlin; Yirmiyan Arthur in Kohima, India; John Minchillo in New York; Hallie Golden in Seattle; and Christie Hampton, Brian Hannon and David Cohen in Bangkok contributed to this report.

A plane is prepared whilst another airplane approaches landing at Heathrow Airport after a fire at an electrical substation shuttered Europe's busiest air travel hub in London, Friday, March 21, 2025.(AP Photo/Alberto Pezzali)

A handwritten sign at a Heathrow Airport tube station in London indicates the airport is closed on Friday March 21, 2025, following a fire at the North Hyde electrical substation the previous night.(AP Photo/Alberto Pezzali)

A handwritten sign at a Heathrow Airport tube station in London indicates the airport is closed on Friday March 21, 2025, following a fire at the North Hyde electrical substation the previous night.(AP Photo/Alberto Pezzali)

The runway at Heathrow Airport is lit again after a fire at an electrical substation shuttered Europe's busiest air travel hub in London, Friday, March 21, 2025.(AP Photo/Alberto Pezzali)

Workers are seen as smoke rises from the North Hyde electrical substation, which caught fire last night, leading to the closure of the Heathrow Airport, in London, Friday March 21, 2025.(AP Photo/Kirsty Wigglesworth)

Travellers arrives at Terminal 5 as London's Heathrow Airport says it plans to resume some flights later Friday after a fire at a nearby electrical substation has caused a closure of Europe's busiest airport in London, Friday, March 21, 2025.(AP Photo/Kin Cheung)

Travellers arrives at Terminal 5 as London's Heathrow Airport says it plans to resume some flights later Friday after a fire at a nearby electrical substation has caused a closure of Europe's busiest airport in London, Friday, March 21, 2025.(AP Photo/Kin Cheung)

People watch a British Airways plane landing as authorities announced a partial resumption of flights after a fire at a nearby electrical substation has caused a closure of Europe's busiest airport in London, Friday, March 21, 2025.(AP Photo/Kin Cheung)

A British Airways plane approaches landing after a fire at a nearby electrical substation has caused a closure of Europe's busiest airport in London, Friday, March 21, 2025.(AP Photo/Kin Cheung)

A British Airways plane approaches landing as authorities announced a partial resumption of flights after a fire at a nearby electrical substation has caused a closure of Europe's busiest airport in London, Friday, March 21, 2025.(AP Photo/Kin Cheung)

Airport employees work as information sign is displayed at British Airways ticket counter at O'Hare International Airport in Chicago, Friday, March 21, 2025. (AP Photo/Nam Y. Huh)

Travelers check their phone as they wait on an airport train to international terminal at O'Hare International Airport in Chicago, Friday, March 21, 2025. (AP Photo/Nam Y. Huh)

Cancellations for British Airways flights to London Heathrow airport are displayed as cancelled on a departures board at JFK International airport, Friday, March 21, 2025, in New York. (AP Photo/John Minchillo)

Smoke rises from the North Hyde electrical substation, which caught fire last night, leading to the closure of the Heathrow Airport, in London, Friday March 21, 2025.(AP Photo/Kirsty Wigglesworth)

British Airways planes are parked at Terminal 5 as Britain's Heathrow Airport has closed for the full day Friday after an electrical substation fire knocked out its power, disrupting flights for hundreds of thousands of passengers at one of Europe's biggest travel hubs in London, Friday, March 21, 2025.(AP Photo/Kin Cheung)

Firefighters extinguish the fire at the North Hyde electrical substation, which caught fire Thursday night and led to a closure of Heathrow Airport in London, Friday, March 21, 2025.(AP Photo/Kirsty Wigglesworth)

Travellers are waiting as Britain's Heathrow Airport has closed for the full day Friday after an electrical substation fire knocked out its power, disrupting flights for hundreds of thousands of passengers at one of Europe's biggest travel hubs in London, Friday, March 21, 2025.(AP Photo/Kin Cheung)

Planes are parked at Terminal 5 as Britain's Heathrow Airport has closed for the full day Friday after an electrical substation fire knocked out its power, disrupting flights for hundreds of thousands of passengers at one of Europe's biggest travel hubs in London, Friday, March 21, 2025.(AP Photo/Kin Cheung)

A fireman works at the North Hyde electrical substation, which caught fire last night, leading to the closure of the Heathrow Airport, in London, Friday March 21, 2025..(AP Photo/Kirsty Wigglesworth)

Smoke rises from the North Hyde electrical substation, which caught fire last night, leading to the closure of the Heathrow Airport, in London, Friday March 21, 2025. (Jonathan Brady/PA via AP)

Smoke rises from the North Hyde electrical substation, which caught fire last night, leading to the closure of the Heathrow Airport, in London, Friday March 21, 2025. (Jonathan Brady/PA via AP)

This image taken from video shows a deserted runaway with parked planes on the background at Heathrow airport, as a fire at the North Hyde electrical substation on Thursday night has led to a closure of Heathrow Airport in London, Friday, March 21, 2025. (Sky News via AP)

Traveller Lauren Clark, left, and Shahin Jade Ali wait at Chhatrapati Shivaji Maharaj International Airport after a fire at Heathrow Airport in London forced its closure, leading to numerous flight cancellations, in Mumbai, India, Friday, March 21, 2025. (AP Photo/Rajanish Kakade)

Firefighters extinguish the fire at the North Hyde electrical substation, which caught fire Thursday night and led to a closure of Heathrow Airport in London, Friday, March 21, 2025.(AP Photo/Kirsty Wigglesworth)

Planes are parked at the Terminal as Britain's Heathrow Airport has closed for the full day Friday after an electrical substation fire knocked out its power, disrupting flights for hundreds of thousands of passengers at one of Europe's biggest travel hubs in London, Friday, March 21, 2025.(AP Photo/Kin Cheung)

British Airways planes are sitting in a hangar as Britain's Heathrow Airport has closed for the full day Friday after an electrical substation fire knocked out its power, disrupting flights for hundreds of thousands of passengers at one of Europe's biggest travel hubs in London, Friday, March 21, 2025.(AP Photo/Kin Cheung)

A traveller arrives with his lugage at Terminal 4 as Britain's Heathrow Airport has closed for the full day Friday after an electrical substation fire knocked out its power, disrupting flights for hundreds of thousands of passengers at one of Europe's biggest travel hubs in London, Friday, March 21, 2025.(AP Photo/Kin Cheung)

Firefighters extinguish the fire at the North Hyde electrical substation, which caught fire Thursday night and lead to a closure of Heathrow Airport in London, Friday, March 21, 2025.(AP Photo/Kirsty Wigglesworth)

Stranded passengers makes their way down unlit stairs due to lifts not working to the car park at Heathrow Terminal 4 in London, Friday March 21, 2025, as consequence of the closure of the airport following a fire at the North Hyde electrical substation last night. (James Manning/PA via AP)

Trollies in the unlit car park at Heathrow Terminal 4 in London, Friday March 21, 2025, as consequence of the closure of the airport following a fire at the North Hyde electrical substation last night. (James Manning/PA via AP)

A flight information screen shows cancelled flights destined for the Heathrow Airport in London, at the Indira Gandhi International Airport, in New Delhi, India, Friday, March 21, 2025. (AP Photo/Shonal Ganguly)

Firefighters extinguish the fire at the North Hyde electrical substation, which caught fire Thursday night and led to a closure of Heathrow Airport in London, Friday, March 21, 2025.(AP Photo/Kirsty Wigglesworth)

Passengers with suitcases waitb on a nearby road after Britain's Heathrow Airport has closed for the full day Friday after an electrical substation fire knocked out its power, disrupting flights for hundreds of thousands of passengers at one of Europe's biggest travel hubs in London, Friday, March 21, 2025.(AP Photo/Kin Cheung)

Firefighters wait at the area around the North Hyde electrical substation, which caught fire Thursday night and lead to a closure of Heathrow Airport in London, Friday, March 21, 2025.(AP Photo/Kirsty Wigglesworth)

Firefighters extinguish the fire at the North Hyde electrical substation, which caught fire Thursday night and lead to a closure of Heathrow Airport in London, Friday, March 21, 2025.(AP Photo/Kirsty Wigglesworth)

Firefighters extinguish the fire at the North Hyde electrical substation, which caught fire Thursday night and lead to a closure of Heathrow Airport in London, Friday, March 21, 2025.(AP Photo/Kirsty Wigglesworth)

Police forces cordon off the area around the North Hyde electrical substation, which caught fire Thursday night and lead to a closure of Heathrow Airport in London, Friday, March 21, 2025.(AP Photo/Kirsty Wigglesworth)

A police officer guards the cordoned off area around the North Hyde electrical substation, which caught fire Thursday night and lead to a closure of Heathrow Airport in London, Friday, March 21, 2025.(AP Photo/Kirsty Wigglesworth)

A police officer guards the cordoned off area around the North Hyde electrical substation, which caught fire Thursday night and lead to a closure of Heathrow Airport in London, Friday, March 21, 2025.(AP Photo/Kirsty Wigglesworth)

Emergency services are seen at the scene in Roseville Road, west London, Friday, March 21, 2025, near the North Hyde electrical substation, which caught fire Thursday night. (James Weech/PA via AP)

Emergency services are seen at the scene in Roseville Road, west London, Friday, March 21, 2025, near the North Hyde electrical substation, which caught fire Thursday night. (James Weech/PA via AP)

FILE - Airplanes are seen at the Heathrow Airport in London, May 27, 2023. (AP Photo/Kin Cheung, File)

FILE - A plane takes off over a road sign near Heathrow Airport in London, June 5, 2018. (AP Photo/Kirsty Wigglesworth, File)

DUBAI, United Arab Emirates (AP) — Widening protests in Iran sparked by the Islamic Republic's ailing economy are putting new pressure on its theocracy.

Tehran is still reeling from a 12-day war launched by Israel in June that saw the United States bomb nuclear sites in Iran. Economic pressure, which has intensified since September when the United Nations reimposed sanctions on the country over its atomic program, has put Iran's rial currency into a free fall, now trading at some 1.4 million to $1.

Meanwhile, Iran's self-described “Axis of Resistance” — a coalition of countries and militant groups backed by Tehran — has been decimated in the years since the start of the Israel-Hamas war in 2023.

A threat by U.S. President Donald Trump warning Iran that if Tehran “violently kills peaceful protesters” the U.S. “will come to their rescue," has taken on new meaning after American troops captured Venezuelan President Nicolás Maduro, a longtime ally of Tehran.

“We're watching it very closely,” Trump told journalists aboard Air Force One late Sunday. “If they start killing people like they have in the past, I think they're going to get hit very hard by the United States.”

Here's what to know about the protests and the challenges facing Iran's government.

Demonstrations have reached over 220 locations in 26 of Iran’s 31 provinces, the U.S.-based Human Rights Activists News Agency reported early Monday. The death toll had reached at least 19 killed, it added, with more than 990 arrests. The group, which relies on an activist network inside of Iran for its reporting, has been accurate in past unrest.

Understanding the scale of the protests has been difficult. Iranian state media has provided little information about the demonstrations. Online videos offer only brief, shaky glimpses of people in the streets or the sound of gunfire. Journalists in general in Iran also face limits on reporting such as requiring permission to travel around the country, as well as the threat of harassment or arrest by authorities.

But the protests do not appear to be stopping, even after Supreme Leader Ayatollah Ali Khamenei on Saturday said “rioters must be put in their place.”

The collapse of the rial has led to a widening economic crisis in Iran. Prices are up on meat, rice and other staples of the Iranian dinner table. The nation has been struggling with an annual inflation rate of some 40%.

In December, Iran introduced a new pricing tier for its nationally subsidized gasoline, raising the price of some of the world’s cheapest gas and further pressuring the population. Tehran may seek steeper price increases in the future, as the government now will review prices every three months.

The protests began first with merchants in Tehran before spreading. While initially focused on economic issues, the demonstrations soon saw protesters chanting anti-government statements as well. Anger has been simmering over the years, particularly after the 2022 death of 22-year-old Mahsa Amini in police custody that triggered nationwide demonstrations.

Iran's “Axis of Resistance," which grew in prominence in the years after the 2003 U.S.-led invasion and subsequent occupation of Iraq, is reeling.

Israel has crushed Hamas in the devastating war in the Gaza Strip. Hezbollah, the Shiite militant group in Lebanon, has seen its top leadership killed by Israel and has been struggling since. A lightning offensive in December 2024 overthrew Iran’s longtime stalwart ally and client in Syria, President Bashar Assad, after years of war there. Yemen's Iranian-backed Houthi rebels also have been pounded by Israeli and U.S. airstrikes.

China meanwhile has remained a major buyer of Iranian crude oil, but hasn't provided overt military support. Neither has Russia, which has relied on Iranian drones in its war on Ukraine.

Iran has insisted for decades that its nuclear program is peaceful. However, its officials have increasingly threatened to pursue a nuclear weapon. Iran had been enriching uranium to near weapons-grade levels prior to the U.S. attack in June, making it the only country in the world without a nuclear weapons program to do so.

Tehran also increasingly cut back its cooperation with the International Atomic Energy Agency, the U.N.'s nuclear watchdog, as tensions increased over its nuclear program in recent years. The IAEA's director-general has warned Iran could build as many as 10 nuclear bombs, should it decide to weaponize its program.

U.S. intelligence agencies have assessed that Iran has yet to begin a weapons program, but has “undertaken activities that better position it to produce a nuclear device, if it chooses to do so.”

Iran recently said it was no longer enriching uranium at any site in the country, trying to signal to the West that it remains open to potential negotiations over its atomic program to ease sanctions. But there's been no significant talks in the months since the June war.

Iran decades ago was one of the United States’ top allies in the Mideast under Shah Mohammad Reza Pahlavi, who purchased American military weapons and allowed CIA technicians to run secret listening posts monitoring the neighboring Soviet Union. The CIA fomented a 1953 coup that cemented the shah’s rule.

But in January 1979, the shah, fatally ill with cancer, fled Iran as mass demonstrations swelled against his rule. Then came the Islamic Revolution led by Ayatollah Ruhollah Khomeini, which created Iran’s theocratic government.

Later that year, university students overran the U.S. Embassy in Tehran, seeking the shah’s extradition and sparking the 444-day hostage crisis that saw diplomatic relations between Iran and the U.S. severed.

During the Iran-Iraq war of the 1980s, the U.S. backed Saddam Hussein. During that conflict, the U.S. launched a one-day assault that crippled Iran at sea as part of the so-called “Tanker War,” and later shot down an Iranian commercial airliner that the U.S. military said it mistook for a warplane.

Iran and the U.S. have seesawed between enmity and grudging diplomacy in the years since, and relations peaked with the 2015 nuclear deal, which saw Iran greatly limit its program in exchange for the lifting of sanctions. But Trump unilaterally withdrew America from the accord in 2018, sparking tensions in the Mideast that intensified after Hamas' Oct. 7, 2023, attack on Israel.

FILE - An Iranian security official in protective clothing walks through part of the Uranium Conversion Facility just outside the Iranian city of Isfahan, on March 30, 2005. (AP Photo/Vahid Salemi, File)

FILE - A customer shops at a supermarket at a shopping mall in northern Tehran, on Sept. 28, 2025. (AP Photo/Vahid Salemi, File)

FILE - Current and pre-revolution Iranian banknotes are displayed by a street money exchanger at Ferdowsi square, Tehran's go-to venue for foreign currency exchange, in downtown Tehran, Iran, on Aug. 28, 2025. (AP Photo/Vahid Salemi, File)

FILE - People cross the Enqelab-e-Eslami (Islamic Revolution) street in Tehran, Iran, on Sept. 27, 2025. (AP Photo/Vahid Salemi, File)

FILE - Protesters march on a bridge in Tehran, Iran, on Dec. 29, 2025. (Fars News Agency via AP, File)

People wave national flags during a ceremony commemorating the death anniversary of the late commander of the Iran's Revolutionary Guard expeditionary Quds Force, Gen. Qassem Soleimani, who was killed in a U.S. drone attack in 2020 in Iraq, at the Imam Khomeini grand mosque in Tehran, Iran, Thursday, Jan. 1, 2026. (AP Photo/Vahid Salemi)