The US Federal Aviation Administration (FAA) has reported an increase in the spotting of unmanned aircraft by pilots in the past one year.
According to FAA figures, the number of sightings has more than doubled from 238 in 2014 to 650 so far this year.
Pilots of a variety of different aircraft were said to have spotted around 16 unmanned aircraft in June of 2014, and 36 the following month.
Around 138 drones were seen by pilots at altitudes of up to 10,000ft during the month of June, followed by another 137 in July.
In addition, firefighters working on controlling wildfire blazes in the western part of the country had to ground their operations on several occasions as safety measures on spotting one or more unmanned aircraft in their immediate vicinity.
Recently, the menace of unmanned aircraft was exposed when a Delta 407 flying in from Orlando narrowly missed hitting a drone at 1,400ft while trying to land at New York's John F Kennedy International Airport. The plane was carrying around 149 passengers and five crew members.
Calling the flying of such aircraft dangerous and illegal, FAA has said that unauthorised users will be subject to strict fines and criminal charges including possible jail time.
FAA has committed to continue educating unmanned aircraft users about where they can operate within the rules through its initiative "Know Before You Fly".
The agency is also supporting the National Interagency Fire Center's "If You Fly, We Can't" efforts to help bring down the interference of drone with firefighting operations.
Meanwhile, the agency announced plans to continue investigating the various incidents that involved the unauthorised use of unmanned aircraft with the help of the law enforcement community.
Image: Recently a Delta flight carrying 154 people had a close call with a drone. Photo: courtesy of Capricorn4049.