A look at some of history's worst air travel disruptions before a fire shut Heathrow

LONDON (AP) — A fire that closed London's Heathrow Airport has sparked one of the most serious disruptions to air travel in years.

More than 1,300 flights were canceled and hundreds of thousands of journeys were disrupted following the blaze at an electrical substation, whose cause is under investigation.

Here is a look at some past incidents:

A faulty software update sent to millions of Microsoft customers by cybersecurity firm CrowdStrike caused technological havoc worldwide. Airlines lost access to their booking systems, thousands of flights were canceled and tens of thousands were delayed, leading to long lines at airports in the U.S., Europe, Asia and Latin America.

A glitch at Britain’s National Air Traffic Services in August 2023 meant flight plans had to be processed manually, rather than automatically. Hundreds of flights were delayed or canceled at the height of the summer holidays. The NATS system had already suffered several software-related failures in the years after it opened in 2002.

As a new coronavirus spread around the globe in early 2020, the world’s airports shut down. Many governments closed national borders and imposed travel restrictions. By April, the number of flights around the world had fallen by 80%. When air travel resumed, it was with masks, mandatory coronavirus tests and other measures that made flying more onerous and expensive. It wasn’t until 2024 that global passenger numbers reached 2019 levels again.

More than 140,000 travelers were stranded or delayed after dozens of drone sightings shut down London Gatwick, south of the U.K. capital and Britain’s second-busiest airport, for parts of three consecutive days before Christmas. A monthslong police investigation failed to identify the culprits or determine how many of the sightings were real.

A computer failure at a British Airways data center forced the airline to cancel all flights from Heathrow and Gatwick on a holiday weekend. The airline blamed a power-supply issue for the incident which affected some 75,000 travelers.

Delta Air Lines planes around the world were grounded when an electrical component failed and led to a shutdown of the transformer that provides power to the carrier’s data center. Delta said that it canceled more than 2,000 flights and lost $100 million in revenue as a result of the outage.

People around the world learned how to pronounce the name of Iceland’s tongue-twisting Eyjafjallajökull volcano (ay-yah-FYAH-lah-yer-kuhl) after it roared to life, sending plumes of ash and dust into the atmosphere. Airspace over northern Europe was shut for several days and airlines canceled flights between Europe and North America because of concerns the ash could damage jet engines. More than 100,000 flights were canceled, stranding millions of passengers, at an estimated cost of $3 billion.

U.S. airspace was closed to commercial flights on Sept. 11, 2011 after hijackers crashed planes into the World Trade Center towers, the Pentagon and a field in Pennsylvania. Thousands of planes were grounded and flights in the air heading for the U.S. were diverted to Canada and Mexico. Flights began to resume two days later, but air travel was forever altered, with passengers facing more rigorous security, more intrusive scrutiny and longer lines.

FILE - Licensed vocational nurse Caren Williams, left, collects a nasal swab sample from a traveler at a COVID-19 testing site at the Los Angeles International Airport in Los Angeles, Monday, Nov. 23, 2020. (AP Photo/Jae C. Hong, File)

FILE - Travelers wear face coverings in the line for the north security checkpoint in the main terminal of Denver International Airport Tuesday, Aug. 24, 2021, in Denver. (AP Photo/David Zalubowski, File)

FILE - Passengers waiting for a flight to Helsinki rest at Lisbon's international Portela Airport on May 10, 2010, as flights were disrupted due to an ash cloud drifting over from a volcano in Iceland that caused major air travel chaos. (AP Photo/Francisco Seco, File)

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)

British travellers Rajih Alshibli and Michele planning to go to Bahrain to see their daughter are stranded 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)

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)

A Ukrainian drone strike killed one person and wounded three others in the Russian city of Voronezh, local officials said Sunday.

A young woman died overnight in a hospital intensive care unit after debris from a drone fell on a house during the attack on Saturday, regional Gov. Alexander Gusev said on Telegram.

Three other people were wounded and more than 10 apartment buildings, private houses and a high school were damaged, he said, adding that air defenses shot down 17 drones over Voronezh. The city is home to just over 1 million people and lies some 250 kilometers (155 miles) from the Ukrainian border.

The attack came the day after Russia bombarded Ukraine with hundreds of drones and dozens of missiles overnight into Friday, killing at least four people in the capital Kyiv, according to Ukrainian officials.

For only the second time in the nearly four-year war, Russia used a powerful new hypersonic missile that struck western Ukraine in a clear warning to Kyiv and NATO.

The intense barrage and the launch of the nuclear-capable Oreshnik missile followed reports of major progress in talks between Ukraine and its allies on how to defend the country from further aggression by Moscow if a U.S.-led peace deal is struck.

Ukrainian President Volodymyr Zelenskyy said Saturday in his nightly address that Ukrainian negotiators “continue to communicate with the American side.”

Chief negotiator Rustem Umerov was in contact with U.S. partners Saturday, he said.

Separately, Ukraine’s General Staff said Russia targeted Ukraine with 154 drones overnight into Sunday and 125 were shot down.

Follow the AP’s coverage of the war in Ukraine at https://apnews.com/hub/russia-ukraine

This photo provided by the Ukrainian Security Service on Friday, Jan. 9, 2026, shows a fragment believed to be a part of a Russian Oreshnik intermediate range hypersonic ballistic missile that hit the Lviv region. (Ukrainian Security Service via AP)

President of Ukraine Volodymyr Zelenskyy, second left, listens to British Defense Secretary John Healey during their meeting in Kyiv, Ukraine, Friday, Jan. 9, 2026. (AP Photo/Danylo Antoniuk)