Gatwick Airport, Britain’s second-largest air hub, reopened on Friday night after officials briefly closed its sole runway in response to an unconfirmed report of another drone incursion. The shutdown followed earlier drone sightings that had created chaos at the airport and delayed tens of thousands of passengers.
The runway had initially been reopened at 6 a.m. Friday after being shut for the better part of 32 hours. Things ran relatively smoothly until just after 5 p.m., when someone reported seeing another drone. Airport officials did not say if they had determined whether a drone had actually flown near the airport, but said that “the military measures we have in place at the airport have provided us with reassurance necessary to reopen our airfield.”
As the police continued to hunt for the culprit, or culprits, behind the incursions, officials at the airport, south of London, were struggling to accommodate the huge numbers of passengers disrupted by what was described as a deliberate act.
The episodes provided the starkest evidence to date of how vulnerable airports across the world are to drones, which are widely available, loosely regulated and more advanced in their technology than equipment meant to guard against the risks they pose.
The authorities reiterated on Friday that they had increased the numbers of officers involved in the criminal investigation, but in a sign of things to come, they had warned early in the day that they could not promise that the airport would remain open on a day when 126,000 passengers were hoping to fly out.
“I cannot guarantee that another drone isn’t going to pop up and disrupt the airport,” said Assistant Chief Constable Steve Barry of the Sussex police. “The situation is being kept under review but we are in a much more positive situation than yesterday. The runway is open and we hope to keep it that way.”
Speaking to reporters outside the airport, Constable Barry said there was “no evidence” that the drone incursions were state-sponsored, adding that they could be the result of “high-end criminal behavior” or “individuals trying to be malicious.”
“We do have persons of interest,” Constable Barry said. The steps being taken to protect the airport, he added, included “technical, sophisticated options to detect and mitigate drone incursions, all the way down to less sophisticated options,” according to the BBC.
“Even shotguns would be available to officers should the opportunity present itself,” Constable Barry said.
Local news reports on Friday showed that the scene at Gatwick had calmed considerably since the previous day, when frustrated, frantic passengers packed the airport’s two terminals. Many travelers trying to either leave the airport or expecting to land there were still stranded, and left to wonder whether they would reach their destinations by Christmas.
Before the shutdown on Friday evening, at least 150 flights had been canceled and there was a heightened military and police presence around the airport. The discount airline easyJet, which like other airlines warned passengers to confirm the status of their flight before leaving for the airport, said that runway movements had been ”restricted to a limited number per hour.” It did not provide details.
Chris Woodroofe, chief operating officer for Gatwick Airport, told the BBC that the airport was taking extra steps to protect air travel. “We have been working overnight with the police, with a number of government agencies and with the military to put in place additional mitigating measures,” he said, declining to provide details.
The Sussex police said they had teamed up with law enforcement agencies from nearby Surrey and greater London as well as the military to mitigate further threats, but they noted that the opening of the runway remained under “constant review.”
The initial shutdown — which, except for one 45-minute stretch, ran from 9 p.m. Wednesday until Friday morning — disrupted hundreds of flights, stranded tens of thousands of passengers and reduced British authorities to playing cat-and-mouse with the rogue drones.
About 20 police units searched the perimeter of the airfield on Thursday for the devices’ operators. By nightfall, the government said it would deploy the military in a bid to reopen the airport, although it was not clear in what capacity.
“Over 90 percent of airports in the world are unprepared for drones,” said Tim Bean, the founder and chief executive of Fortem Technologies, which is testing a drone defense system on several American runways.
Chris Grayling, Britain’s transportation minister, acknowledged as much in an interview with the BBC on Friday. “We’re going to have to learn very quickly from what’s happened,” Mr. Grayling said, describing the episode as “unprecedented, anywhere in the world.”
He told the BBC that security officials had matters in hand, and that the airport would not have reopened if officials did not believe there would be further disruptions. He added that security was being increased at the country’s other airports to prevent similar drone incursions.
Mr. Grayling also responded to questions about why a drone could not just be shot down by noting that the authorities’ ability to respond in such cases was limited.
“You can’t just fire weapons haphazardly in what is a built-up area around the airport, because there are consequences if that goes wrong,” Mr. Grayling said. “They have to take steps that are doable and safe.”
The police have been combing through hundreds of tips that had come in since Thursday, and said on Twitter that they were focusing their investigation on the “identity or location of the #drone operator.” They said there were “no indications to suggest this is terror related” and no evidence on anyone having unauthorized access to the airfield.
Gatwick employees first spotted a pair of drones flying over the perimeter fence and into the runway area around 9 p.m. Wednesday, officials said. The devices reappeared Thursday morning, and the police searched the perimeter for the drones’ operators.
Gatwick is London’s second biggest airport, behind Heathrow, but it is busy by any relative measure, with hundreds of flights a day to destinations all around the world. Planes bound for Gatwick were diverted to other British airports, as well as Amsterdam and Paris, and the disruptions in London caused ripple effects all over Europe.
The ability of relatively small drones to shut down a huge part of infrastructure serving a large city like London has raised questions about the measures in place to deal with the small machines.
As ownership of the devices has increased, the potential for run-ins with aircraft has also risen. Britain passed laws this year to make it illegal for a drone to fly higher than 400 feet or to fly within a kilometer of an airport, about six-tenths of a mile.
The lengthy closing of the airport during a peak travel season highlighted how rapidly developing technology could allow someone so inclined to bring institutions and infrastructure to a standstill with relatively few resources.
“The impact of a lot of internet and consumer technology has massively increased the capabilities of people who would have historically had to be well funded and organized,” said Chris Yiu, a senior fellow for technology at the Tony Blair Institute, said in an interview on Thursday. “That’s no longer the case.”
Mr. Woodroofe, Gatwick’s general manager, said in his interview with the BBC on Friday that the episode had demonstrated that there was “an awful lot more work that needs to be done across the U.K. and internationally to address the risk of drones to airports.”
Although new technology has been tested and a company in the Netherlands has even trained eagles to hunt for drones, there is not a global standard for managing the potential risk posed by the devices.
“The reality is that, as we sit here today, there is no commercial solution that’s licensed to operate at airports that’s proven, and so you’re absolutely right — we have called in government agencies and the military to assist us in getting Gatwick Airport back open again to counteract this unprecedented event, this criminal act,” Mr. Woodroofe added.