LONDON — Gatwick Airport, Britain’s second-busiest air hub, was shut down late Wednesday and into Thursday after a drone was seen flying illegally nearby, in what the authorities said was a deliberate act to disrupt flights during one of the year’s busiest travel seasons.
Arriving flights carrying 10,000 passengers were diverted because of the shutdown, Gatwick officials said, with some travelers forced to land at airports as far away as Paris. Departing flights were initially grounded from 9 p.m. Wednesday to around 3 a.m. Thursday.
The airport, which is about 25 miles south of central London and connects fliers to 230 destinations in 70 countries, was shut again at 3:45 a.m. after another reported drone sighting.
By 4 p.m. local time, the drone pilot, or pilots, had not been found and all travel in and out of the airport was still shut down. Airport officials said they expected the disruption to last into the weekend.
The local police in Sussex, outside London, described the flying of a drone so close to the airport as a “deliberate act,” but said there were “no indications to suggest this is terror related.”
Nonetheless, the Ministry of Defense had gotten involved by Thursday afternoon.
“We are deploying specialist equipment to Gatwick Airport to assist Sussex Police,” a ministry spokesman said, declining to provide details.
As part of an investigation with the Surrey police and the National Police Air Service, the Sussex police used Twitter to ask for the public’s help in finding whoever was flying the drone, or drones. The police described the devices as “of industrial specification.”
“We are appealing for information to help us identify the operators of the #Gatwick #drones,” the police wrote.
As the shutdown continued, Gatwick and the airlines that use it advised passengers to check the status of flights before coming to the airport. A total of 760 flights carrying 115,000 passengers had been scheduled to leave and arrive Thursday before the day started.
A spokeswoman for Heathrow Airport, which is Britain’s busiest and also in London, said it was heightening security in response to the events at Gatwick. “We have increased patrols around our airport,” she said, “and would like to remind the public that unauthorized use of a drone around an airport can carry a custodial sentence of up to five years.”
Chris Woodroofe, Gatwick’s chief operating officer, told Sky News that two staff members first spotted a drone Wednesday night. “Since then, the drone has appeared and disappeared and appeared and disappeared,” he said. The last reported sighting was around 11 a.m.
Passengers whose trips had been disrupted vented their frustration on social media. One traveler wrote that she had taken a “tour of every London airport” after stops at Stansted and Heathrow, while a man who said he had been redirected to Paris wondered if his dog would walk itself.
The scene at the airport terminals was one of bedlam as stranded passengers unable to make alternative plans with airlines by phone swamped ticket counters in the terminals. Crowds of people slumped over their luggage, refreshing their phone screens in the hopes of getting updated flight information. Others, seeming utterly defeated, appeared to stare off into space.
Erica Perez, a personal trainer bound for Nice, France, for Christmas, was waiting in the easyJet line. She said she had been waiting on hold for more than an hour trying to get through to someone at the budget airline until her battery died. The line at the airport, she said, had not moved in three hours.
“How will they rearrange these flights for all these people?” Ms. Perez said. “All the flights tomorrow are already fully booked for Christmas weekend.”
Alison Carter, who teaches German, said she was baffled at how such a thing could happen.
“How does the airport not have the resources to down the drone?” she said. “What kind of message does this give to terrorists and criminals?”
By the afternoon, many airlines were offering refunds rather than rescheduling flights because of the high demand.
As drones’ popularity has increased in recent years, so have reports of the devices’ role in causing airline disruptions. The number of commercial drone licenses in Britain rose to 3,800 in 2017 from 2,500 the year before. The number of drone incidents rose to 93 in 2017 from 71 a year earlier.
New laws introduced in Britain in May restrict drones from flying above 400 feet or within a kilometer, or about three-fifths of a mile, of airport boundaries. Violators can be punished with up to five years in prison in Britain.
Since Nov. 30, the owners of drones weighing more than 250 grams, or a bit more than half a pound, have had to register them with the Civil Aviation Authority, and those who fly them must pass an online safety test. Not following these steps can result in fines of as much as 1,000 pounds, or around $1,270.
This is not the first time an airport has been shut down over the appearance of a drone. Gatwick was closed after drone sightings in July 2017. Airports in Chengdu, China; Dubai, the United Arab Emirates; and Ottawa have also had to shut down because of drone sightings.
“I’m somewhat surprised this doesn’t happen more often,” said Ulrike Franke, a policy fellow at the European Council on Foreign Relations, who specializes in drones. “The Gatwick case is very extreme because of the length of time.”
Many drones have internal GPS software that prevents pilots from flying them into restricted areas like airports. But Ms. Franke said the systems were imperfect and could be subverted by people who understand their workings.
She said the amount of time the drone had been above the airport supported the idea that it was being flown there deliberately. “This very much points to this being planned and not just some rogue hobbyist,” she said.
Ms. Franke noted that most airports have electrical jammers or other anti-drone measures in place to quickly get rid of drone threats.
“The danger is pretty much the same as with birds. A drone may get caught in an engine during take off and landing,” she said. “It’s plastic, metal and lithium batteries that can explode.”
The episodes highlight broader security issues related to drones and nuclear facilities, prisons and even targeted assassinations, she added. In Britain, drones are used for inspections of infrastructure like nuclear power stations, wind turbines and railroads.
“There is a real worry,” she said.
In an interview with the BBC, Baroness Sugg, Britain’s aviation minister, said the government was already considering tighter regulation of drones.
“Technology in this area is obviously moving incredibly quickly, but we do need to ensure that we’re able to stop such activity in future,” she said.
Gatwick has less traffic than major European airports like Schiphol in Amsterdam, which has six runways, Frankfurt Airport and Charles de Gaulle in Paris, which each have four.
But runway space in London is tight. Heathrow, which has two runways, got approval for a third this year because it is running out of capacity and losing ground to other European hubs.
Britain’s Airports Commission had also looked into a new runway at Gatwick, but concluded that it was better for passengers and freight to expand Heathrow.
Gatwick said it was expecting a record 2.9 million passengers during the Christmas period, with 73,000 passengers expected to travel through the airport on Dec. 23 alone. It could get even busier with 142,000 people booked to fly on Dec. 30.