Unmanned aerial vehicles (UAVs), commonly known as drones, have been causing increasing concern for aviation authorities and experts, following several reported incidents of drones coming within close range of people, high-profile buildings, events, and aircraft.

In 2015, a journalist for the Qatar-based network Al-Jazeera was fined 1,000 euros ($1,137.65) by a French court for flying a drone over central Paris. Tristan Redman was arrested in the Bois de Boulogne park for flying the drone but Al-Jazeera said in a statement that he only wished to “illustrate a piece to camera on domestic drones.”

And last month the head of Portugal’s national airline, TAP, called for all drones in the country to be grounded, following a series of near-misses with commercial aircraft, according to the Associated Press.

“Due to the irresponsible behavior of some — and I’m speaking in a European and global context — (drones) are being used very badly, in a very dangerous way, and that worries us,” TAP Air Portugal President Fernando Pinto said.