London airport reopens after drones sparked shutdown

London’s Gatwick Airport reopened Friday after drones shut down the airfield and canceled incoming and outgoing flights. 

The airport said it expected many delays following the incident.

“We are, however, expecting knock-on delays and cancellations to flights,” the airport said in a statement to The Associated Press. “If you are due to travel from Gatwick today, we strongly recommend that you check the status of your flight with your airline before departing for the airport.”

{mosads}The cancellations left thousands of travelers stranded at one of London’s largest airports after authorities became concerned of a collision between what police described as industrial-grade drones and an airliner. The drones were first spotted Wednesday evening local time.

Police have not appeared to rule out the possibility that the drones could return and have joined with the military and aviation authorities to track down those responsible for the disruptions. They have said there is no indication the incident is related to terrorism.

U.K. Transport Secretary Chris Grayling said there had been about 40 sightings of “a small number of drones” while the airport was shut down, calling the incident “unprecedented.”

Aviation expert Jon Parker told CNN that the scale of disruption was like nothing he had seen before.

“The usual practice [when a drone is spotted] is to suspend flights for half an hour, which is the usual battery lifespan for drones,” said Parker, head of the drone training company Flyby Technology.

In the case of Gatwick, he said, “whoever is responsible for this has had several batteries and have brought their drones back to the ground to put new batteries on them.”