A report of drone sightings from the Federal Aviation Administration (FAA) shows that despite a new registration scheme, near misses between unmanned and piloted aircraft in the US are on the rise. Sightings by pilots and airport officials have steadily increased from less than one a day in 2014 to more than 3.5 between August 2015 and January of this year, many of them from commercial passenger aircraft.

In the most serious incident, the pilot of an American Airlines jet last September had to swerve to avoid a drone. On 13 September, flight 475 took off from Atlanta, Georgia en route to Charlotte, North Carolina. It was climbing to 3,500 ft when the pilot of the Airbus had to take evasive action to avoid a collision with an unidentified unmanned aerial system (UAS), or drone. The pilot told the FAA that he or she had “just missed” the drone.

In another incident in November, a helicopter leaving St Louis Children’s Hospital in Missouri encountered a black and grey drone 1,400 ft above a city centre park. The pilot of the air ambulance reported that he had to make a steep banking turn to avoid the UAS, passing it at less than 100ft. There were no patients on board, and no reports of any injuries or damage.

In both cases, local law enforcement was notified but no arrests appear to have been made.

Of the 582 sightings of drones reported to the FAA between August and January, there were two other instances where pilots were forced to take evasive action. In October, a helicopter pilot approaching Miami airport had to swerve after a drone approached to within 150 feet.

The closest shave happened in December, when the pilot of a helicopter in Concord, California, reported seeing a UAS as close as five feet away from his aircraft, at an altitude of 1000ft.

“We have a number of educational initiatives with our government and industry partners to teach drone operators how to fly safely, including the drone registry we launched last December,” said FAA administrator Michael Huerta. “But enforcement goes hand in hand with education, and we will take action against anyone who operates irresponsibly to the full extent of the law.”

More than 406,000 people have registered since the registry went live in late December. The process costs $5 and requires drone owners to mark their registration number somewhere on the drone itself. Toy drones weighing less than 250g are exempt from registration, but none of these would have had the range or endurance to reach the altitudes reported in the near misses above.

The FAA is also slowly developing an air traffic control system for drones that would allow UAS to automatically avoid manned aircraft and each other.

“The biggest single concern of FAA is manned aircraft,” said Bob Young, CEO of PrecisionHawk, a startup helping to build and test the system. “This quite correct, as flying objects are not like cars. You can’t just put up a fence to keep them out. When I get on an flight, I want regulators to keep drones a long way from my airplane.”