A drone protest at Heathrow Airport failed to take off after some of the toys appeared to be prevented from working by what the climate change activists suspect were signal jammers.
Environmental protest group Heathrow Pause, a splinter group of the Extinction Rebellion movement but separate from it, had intended to fly the devices in the 5km exclusion zone around the transport hub in an attempt to disrupt flights.
The group claimed that of three attempted drone flights, at least one had flown “successfully”, although no departures from the airport had been affected.
But in a video released by the group in the early hours of Friday morning, one activist can be seen attempting to get the small device to work and is heard to say: “They’re jamming the signal.”
Heathrow and police refused to comment on specific measures they may have taken to stop the protesters’ drones from working, but an expert said technology exists which can jam signals between operators and drones.
Richard Gill, chief executive of Drone Defence, told the PA news agency: “That technology is definitely available and can do exactly that.
“When a drone is operated remotely it relies on a radio connection between the drone and the pilot.
“Interference can cut that connection between the operator and the drone.”
He added: “We’re not privy to what the Metropolitan Police have deployed at Heathrow,” but said authorities have updated their approach since drones disrupted flights at Gatwick Airport last Christmas.
Heathrow Pause named two drone pilots who were arrested on Friday morning only as Marko and Steffen and said a man named Frank, who was filming the activists, was also detained.
Former Paralympian James Brown was also arrested at Terminal 2. He told PA said there were up to 35 people willing to fly the devices throughout the day.
Mr Brown, who is partially sighted, did not actually fly a drone and said he held it above his head.
He added police had visited his home address on Thursday evening, which was part of a pre-emptive wave of arrests in which officers detained three women and four men.
Mr Brown said: “The police actually came to my house last night but I’d already gone by then.
“My wife was there and she was really terrified.”
12 people were arrested, according to the Metropolitan Police, with Extinction Rebellion co-founder Roger Hallam also among the suspected would-be pilots.
The activists being held on suspicion of conspiracy to commit a public nuisance within the perimeter of Heathrow Airport are aged between their 20s and their 60s.
Reacting to the arrests, the group said: “The real objective was always to trigger a sensible, honest conversation, throughout society, on the dangerous folly of Heathrow expansion, with the ultimate objective of cancelling the third runway.
“That conversation is now happening. It is incumbent on all of us to keep it going.”
Scotland Yard said a dispersal order had been put in place at Heathrow until 4.30am on Sunday “to prevent criminal activity which poses a significant safety and security risk to the airport”, and a large police presence was seen in the airport area on Friday morning.
Planes landed at the airport as normal, with the first flights touching down just before 5am.
Earlier this week, a senior Metropolitan officer advised Heathrow passengers to travel as normal and said they were “confident” disruption would be kept to a minimum.
Deputy Assistant Commissioner Laurence Taylor said: “We will be arresting anybody who commits unlawful offences.
“We are really clear that it is unlawful, it is a criminal offence, and anybody who turns up expecting to fly drones in that exclusion zone will be arrested.”
Heathrow Airport confirmed its runways were open and said they were committed to addressing climate change.
It said in a statement: “We will continue to work with the authorities to carry out dynamic risk assessment programmes and keep our passengers flying safely on their journeys today.
“We agree with the need for climate change action but illegal protest activity, designed with the intention of disrupting thousands of people, is not the answer.
“The answer to climate change is in constructive engagement and working together to address the issue, something that Heathrow remains strongly committed to do.”
Friday morning’s action was the latest in a string of climate change protests this year, including the widespread action in London in April, which saw Extinction Rebellion bring sites including Oxford Circus and Waterloo Bridge to a standstill.