But a drone — or drones — prompted the cancellation of more than 150 flights at London’s Gatwick Airport over the past two days. Flights had resumed Friday morning, but then Friday evening, flights were once again suspended after reports of a new sighting. Later still, the airport reported via Twitter that flights had resumed once again.

Officials said there were more than 40 drone sightings, the first one Wednesday evening. The last suspected sighting was just after 5 p.m. Friday, prompting the airport to announce that it was suspending flights while it investigated.

AD

AD

“This is an unprecedented event,” Transport Secretary Chris Grayling told the BBC on Friday. “There’s not been anything like this anywhere in the world.” It was a “new kind of attack,” he said, and while they hadn’t ruled anything out, he said that the government didn’t think it was state-sponsored.

On Saturday, Sussex police said in a statement that they had arrested two suspects on Friday night. They did not identify the 47-year-old man or 54-year-old woman, but said both are from Crawley, a town near the airport. They were detained “on suspicion of disrupting services of civil aviation aerodrome to endanger or likely to endanger safety of operations or persons.”

Before the arrests were made public, police said that the incident wasn’t considered terrorism-related but that various lines of inquiry were being investigated, including the possibility that it was an “environmental protest.”

AD

AD

Sussex Police Assistant Chief Constable Steve Barry told reporters Friday that “in terms of motivation, there is a whole spectrum of possibilities, from the really high-end criminal behavior all the way down to just individuals trying to be malicious.”

Experts say that drones, even small ones, can cause considerable damage to aircraft. Last year, a drone collided with a passenger plane above Quebec City in Canada. The plane landed safely, but officials said that if it had collided with a different part of the plane, it could have been “catastrophic.”

It was unclear how, exactly, U.K. authorities attempted to block or bring down the drones. On Thursday, the government brought in the army, which deployed “specialist equipment,” according to the Ministry of Defense.

AD

When asked whether things like “lasers, drone catching nets, radio wave fences” were installed at the airport, Grayling, the transport secretary, was vague, but he told the BBC on Friday morning that “a variety of things” have been done so that the airspace could be reopened.

AD

He also said that simply shooting down a fast-moving drone wasn’t a possibility.

“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,” he said.

Geoff Moore, business development manager at Blighter Surveillance Systems, a U.K. company that designs radars that detect and track drones, said that he thought it was probably just a single large-scale commercial drone that was buzzing around Gatwick. He said they are capable of flying for up to three hours.

AD

“In an area like Gatwick, which is very flat, the drone could be piloted from two to three miles way,” he said, adding that it was possible that the drone was preprogrammed so that the pilot didn’t need to be in constant communication with the device. “The pilot can disappear, he won’t be transmitting radio signals, so there’s no ability to identify the drone,” he said.

AD

“In U.K., you’re not allowed to fly a drone within one kilometer of an airfield,” he said, “but the problem is you can’t legislate for people who want to do bad things and can quite happily fly drones into restricted zones.”

One Twitter user wrote Friday evening about getting caught up in the latest drone sighting.