On the pilot's computer screen, planted at ground level a few yards from the airport runway here, the data streaming across the display tracked an airplane at 1,300 feet above a small city on the coast, making perfect circles at 150 miles per hour.

To the pilot's right, a sensor operator was aiming a camera on the plane to pan, tilt and zoom in a search among the houses on the ground for people who had been reported missing.

On his screen, cartoonlike human figures appeared in a gathering around a camp fire between the houses.

"There they are," Andrew Regenhard, the pilot and a student, said in a flat tone that seemed out of place with a successful rescue mission.

In fact, no one was missing; the entire exercise used imaginary props and locales. Mr. Regenhard was taking part in a training session at the University of North Dakota. The first to offer a degree program in unmanned aviation, the university is one of many academic settings, along with companies and individuals, preparing for a brave new world in which cheap remote-controlled airplanes will be ubiquitous in civilian air space, searching for everything from the most wanted of criminal suspects to a swarm of grasshoppers devouring a crop.

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"The sky's going to be dark with these things," said Chris Anderson, the former editor of Wired, who started the hobbyist Web site DIY Drones and now runs a company, 3D Robotics, that sells unmanned aerial vehicles and equipment. He says it is selling about as many drones every calendar quarter — about 7,500 — as the United States military flies in total.

The burst of activity in remotely operated planes stems from the confluence of two factors: electronics and communications gear has become dirt cheap, enabling the conversion of hobbyist radio-controlled planes into sophisticated platforms for surveillance, and the Federal Aviation Administration has been ordered by Congress to work out a way to integrate these aircraft into the national airspace by 2015.

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The rapidly expanding market has not gone unnoticed by lawmakers and privacy watchdogs. On Wednesday, the Senate Judiciary Committee will hold a hearing on the privacy implications of drones like the ones being developed at Grand Forks.

Senator Patrick Leahy, the Vermont Democrat who is chairman of the committee, said this year: "This fast-emerging technology is cheap and could pose a significant threat to the privacy and civil liberties of millions of Americans. It is another example of a fast-changing policy area on which we need to focus to make sure that modern technology is not used to erode Americans' right to privacy."

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Some fans of the technology wince at the word "drone," which implies that there is no pilot. And they have grown resentful about the alarms raised over privacy issues, noting that a few city and state governments have begun banning drones even where they do not yet operate.