Police have vowed to arrest environmental protesters if they go ahead with plans to disrupt flights at Heathrow airport by sending drones into the air.
Heathrow Pause, an offshoot of Extinction Rebellion, says the devices will be flown at head height and away from flightpaths on Friday to avoid any safety risk.
But the Metropolitan Police said the action would be “criminal” and anyone taking part would be arrested.
Deputy assistant commissioner Laurence Taylor said police had been preparing for the demonstration for weeks to minimise any potential disruption to flights at Britain’s busiest airport.
“Far from this being a lawful protest, this is the deliberate and criminal targeting of an essential part of the UK’s national infrastructure that thousands of people rely on every day and it will not be tolerated,” he added.
“We would urge anyone planning to take part in this activity to reconsider. Airspace around all airports is restricted for public safety and security, and we take the flying of a drone within airspace used by passenger planes very seriously. Anyone caught flying a drone without permission must expect to be arrested and prosecuted.”
Mr Taylor cited the chaos caused by drone sightings that shut down Gatwick airport before Christmas as an example of the disruption such a protest could cause.
“Drone use in restricted airspace has the capability to not only cause a significant safety risk, but also cause great disruption to the public at the airport being targeted and connecting airports internationally,” he added.
“The police’s job is to detect and stop criminal activity in a proportionate way, and there is a robust policing plan in place to ensure that we are in a position to deal with any illegal activity as quickly and efficiently as possible.”
He urged air passengers to travel as normal on Friday, adding: “I would urge people to come on Friday because we’re going to do everything we can to prevent any disruption and I am confident we will be successful in that.
Heathrow Pause said its activists were “prepared to pay a very high price” to protest against the planned third runway at the airport, and are also calling for the government to “tell the truth” about global warming and act on parliament’s declaration of a climate emergency.
Demonstrators including Extinction Rebellion co-founder Roger Hallam met officers at a London station on Tuesday, and said they would cooperate with police “as far as possible”.
Heathrow Pause said the drones would be launched at 3am on Friday and then “at regular intervals throughout the day”, with advance notice given to relevant authorities.
In a statement, the group said its actions were a “humanitarian act intended to save millions of innocent lives that will be lost if carbon emissions are not drastically reduced”.
Valerie Milner-Brown, a 64-year-old writer who is to pilot one of the drones, said: “I don’t want to get arrested, but it feels like it’s the last resort for our government to take notice.
“I’m a grandmother and I care deeply about my children’s and grandchildren’s futures – and I would never do anything to put a life at risk.”
Mr Hallam said the Heathrow expansion would be the “biggest carbon-intensive infrastructure project in Europe”.
It comes after waves of Extinction Rebellion demonstrations across the UK and around the world, seeing more than 1,000 protesters arrested for blocking roads and bridges in London in April.
A spokesperson for Heathrow airport said it agreed with the need to act on climate change but disrupting passengers was “counterproductive and irresponsible”.
“Flying a drone within 5km of Heathrow is illegal and any persons found doing so will be subject to the full force of the law,” he added.
“In order to ensure that our operation remains open and safe, we are working closely with a number of stakeholders including the police ... we will mitigate the impact of this illegal action and operate in a way that is safe at all times.”
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