As drones gain popularity with hobbyists, airplane pilots are in increasing danger of serious accidents. c

A report about drone incidents released on Friday by a research group at Bard College said that there were 327 incidents of drones flying too close to piloted aircraft from December 2013 through September 2015. The report’s authors said they counted 28 incidents of pilots taking evasive action to avoid a collision.

In one instance over the summer in Charlottesville, Va., a drone flew within 25 feet of an airplane. The pilot said he didn’t have enough time to react.

These types of close calls between drones and airplanes are among the many reasons government officials are trying to create regulations for flying drones. The Federal Aviation Administration is finalizing proposed rules that would govern how businesses can use drones, a process that could take up to another two years to complete.

In the meantime, companies must get permits to use drones. However, some businesses like Amazon AMZN that want to use drones to deliver goods complain that the permitting process is too slow and that it hampers innovation.

As for the consumer market, the U.S. Transportation Department and the FAA want to require all hobbyists to register their drones in a central system that the agencies hope to complete before the holidays. The government recruited representatives from drone advocacy groups, drone manufacturers, and retailers like Amazon and Google GOOG to make recommendations for the new registration process.

The government hopes that the registrations system will help it track drones and pinpoint who is responsible for flying in restricted areas or in dangerous situations like near an airport. Part of the proposed process would require that hobbyists add to their registration number to somewhere on the drone.

However, as the Bard College report highlights, having a registration number on a drone may not be helpful when it comes to incidents like close calls with airplanes. Pilots who fly near drones will likely be traveling too fast to see the number and will therefore be unable to report it to authorities.

Some government officials like U.S. Sen. Charles Schumer (D-NY) are calling for so-called geofencing technology to be installed in drones that would automatically prevent them from flying into “no-fly-zones” like airports. But even that proposed solution has some critics. The Bard College report cites R. John Hansman, a director of the MIT International Center for Air Transportation who said that technology is “relatively easy to defeat if you don’t want to comply with it.”

“So the whole idea of geofencing is pretty bogus,” Hansman is quoted in the report. “It’s useful if you have a cooperative user. But a non-cooperative user who doesn’t want to geofence can get around it.”

Still, many organizations are working on technology to prevent dangerous collisions. NASA, with the help of universities, drone makers, and retailers, is developing a drone air-traffic control system that, in theory, would track drones as they fly and automatically divert them if they are in danger of colliding with piloted aircraft.

On Thursday, Stanford University, one of the partners, said it had created software that could identify when drones are about to crash into each other and, instead, steer them clear of a crash. It’s a small step in will likely be a years-long project to create a viable system.

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