The number of reported near-misses between drones and planes is on the rise, according to new figures.
Freedom of information requests by the i newspaper show that there have been 49 proximity reports by pilots since April 2014.
Pilots have called for better safety regulation to prevent a collision.
Drone users are advised to consult Civil Aviation Authority regulations and obtain permission from landowners before flying their devices.
But the figures show that in the first four months of 2016, there were 15 reported near-misses, more than half of total of 29 in the previous 12 months.
Civil Aviation Authority data shows that there have been 16 incidents where there was a serious risk of collision and 12 where the safety of the aircraft may have been compromised.
Steve Landells, flight safety specialist at the British Airline Pilots Association (Balpa), said: "Unless action is taken, Balpa believes the risk of collision is unacceptably high."
Rules already in place for drone users say they must be able to see the craft at all times and must not fly above 400ft (122m).
Drones fitted with cameras must not be flown within 50m (164ft) of people, vehicles or buildings, or over congested areas or large gatherings such as concerts and sports events.
In the Queen's Speech it was announced that the Government would introduce new regulations on drones in a Modern Transport Bill.