WASHINGTON (AP) -- Pilot reports of drone sightings so far this year are more than double last year, according to the Federal Aviation Administration, raising concern about the potential for a deadly collision.

FILE - In this June 11, 2015 file photo, a hexacopter drone is flown in Cordova, Md. (AP Photo/Alex Brandon, File)

There have been more than 650 reports this year by pilots of unmanned aircraft flying near manned aircraft, the FAA said in a statement. There were 238 drone sightings in all of 2014.

The reports come from pilots of a variety of aircraft, including many large airliners. The concern is that if a drone collides with an aircraft engine, it could disable the engine much like birds do sometimes when they get chewed up by engines. Also, a high speed collision with a drone might damage the surface of a plane, changing the airflows in a way that makes the plane difficult to maneuver.

There were 16 drone sightings reported in June 2014, and 36 the following month. This year, there were 138 reports from pilots flying up to 10,000 feet in altitude in June, and 137 reports in July.

Earlier this week, crews on four commercial flights spotted a drone while preparing to land at Newark Liberty International Airport in New Jersey. None of the pilots were required to make evasive maneuvers as a result of the sightings. The planes were between 2,000 and 3,000 feet in the air and eight to 13 miles away from the airport.

The FAA generally restricts drone flights to beneath 400 feet and at least 3 miles from an airport.

Flying a drone "anywhere near" an airplane can bring criminal charges and fines up to $25,000, according to the FAA.

Firefighters battling wildfires in the West have been forced to ground their operations on several occasions after drones were spotted.

Suspected drones interfered with aircraft fighting at least 13 wildfires so far this year, up from four fires last year and only scattered incidents before, according to the U.S. Forest Service. Last month, crews were grounded for 20 minutes as flames spread in a wildfire that closed Interstate 15 in Southern California and destroyed numerous vehicles after five drones were sighted.

Firefighting agencies have introduced public service announcements to warn drone hobbyists, while lawmakers are seeking stiffer penalties for interfering.

The FAA said it is working closely with law enforcement to identify and investigate unauthorized drone operations. The agency has levied civil penalties for several unauthorized flights around the country, and has dozens of open enforcement cases.

"The FAA encourages the public to report unauthorized drone operations to local law enforcement and to help discourage this dangerous, illegal activity," the statement said.

Hobbyists are allowed to fly small drones, which are hardly different from model aircraft, for non-commercial purposes as long as they abide by a few rules, including keeping the aircraft within the line of sight of the operator at all times.

The FAA and the Academy of Model Aeronautics, an association for hobbyists, as well as other organizations representing the drone industry, have a publicity campaign called "Know Before You Fly" to educate drone operators on the rules.

The FAA recently passed a milestone of 1,000 permits granted to businesses to fly drones for aerial photography, to monitor pipelines and electrical transmission towers, and to inspect smokestacks, crops and the undersides of bridges, among other uses.

 

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