It's a kite. It's a model airplane. It's ... the sheriff!

It looks like a model plane, and sounds nearly silent. It costs $30,000, and could pay for itself in its first hour of use.

Law-enforcement officials in Los Angeles County, who police 10.5 million people – say it is the future of policing in America.

"It" is a drone. The three-feet-long, remote-controlled airplane with tiny video cameras can fit in a four-inch-diameter tube – and thus in a car trunk, or over the shoulder like a quiver of arrows.

The tiny drone will be able to provide law enforcement officers with a bird's-eye view of just about anything. It's intended to find lost hikers, skiers, surfers, children, elders, and more. It can also be used in hostage situations and other violent standoffs in rural or urban areas and to surveil fleeing crime suspects.

Privacy advocates worry that a drone could peer too far into private lives because cameras could intrude on citizens through windows and into backyards. Law officers say it is more cost-effective than a helicopter.

"The potential savings of this are astronomical compared to the high cost of owning, storing, and using the helicopters that we now use," says Commander Sid Heal of the Los Angeles County Sheriff's Department (LASD). Helicopters cost between $600 to $1,200 per hour to operate, he says, not including the number of needed personnel: usually at least three (one on the ground, two in a copter). Buying a helicopter can cost up to $2 million.

"Not only that, helicopters are often unavailable altogether or too slow to the scene to be helpful," says Mr. Heal.

Known as "SkySeers," the drones were designed by Octatron, a subsidiary of Chang Industries, a defense contractor in southern California. A prototype has been in development for seven years.

Users of a drone first unfold its wings from the 4-inch diameter tube, then they grasp the drone's chassis from below like a child ready to throw a paper airplane.

Once the drone is airborne (up to about 300 feet), users can direct it to a chosen site via a small, accompanying computer, which has a small monitor that can show what the drone's cameras are seeing. Using precise coordinates, the drone can be directed to loop around a fixed point, or survey point to point as directed by remote control of a person on the ground.

Because of their portability and versatility, drones could become indispensable tools for the sheriff's department activities after testing resumes possibly within a couple weeks or September at the latest, according to officials.

The LASD would be the first law-enforcement agency in the US to employ drones, and depending how much value they end up providing relative to the cost, one drone could be available at each of the 20 sheriff's stations.

After the LASD demonstrated use of the drone in late June, the new technology raised the ire of privacy-rights activists.

"What concerns us is that privacy is fundamentally a right to be let alone and go about your business and daily life without having the government looking over your shoulders," says Kurt Opsahl, staff attorney for the Electronic Frontier Foundation, a nonprofit organization, which aims to protect people's digital rights. "It is as disturbing if they are looking over your shoulder with a drone flying overhead as much as over your shoulder literally," he says.

But others disagree. "While there may be a potential threat to privacy with the ... new drone, if the device is used for the reasons the sheriffs have stated, I don't think there is a need for any attempts to ban its use," says Robert Pugsley, a law professor at Southwestern Law School, Los Angeles.

For their part, officials at the LASD say the cameras are not currently powerful enough to identify the gender of a person on the ground – or see clearly into a bedroom.

"This is intended for search and rescue, quick deployment during a fast-moving fire, or even a post-Katrina search operation," says Sam de la Torre, the SkySeer's developer. He notes that anything the SkySeer can see is permitted under current federal and state laws regarding helicopter surveillance. "We are not going to be looking in back windows and invading privacy. We are going to be trying to save lives," he says.

The Federal Aviation Administration requires the LASD and Octatron to submit papers for approval so that SkySeer – now just a prototype – can be further tested across Los Angeles County. LASD officials say the approval is a small hurdle and should happen within weeks.

As close as 20 feet, the LASD drone prototype sounds about as loud as a mosquito buzzing in the ear. Farther than 20 feet, the drone is completely undetectable.

It moves at about 30 miles an hour, and its battery lasts 75 minutes. But a battery can be changed in five minutes, and on-the-ground recharging can keep the drones airborne indefinitely.

The size, weight, and cost of these new drones may make them more ubiquitous than the larger drones, which the US border patrol in Tucson, Ariz., began using in September to target illegal immigrants. The large UAVs (unmanned aerial vehicle) called the Predator B reach speeds of 253 miles per hour, can hover between 15,000 and 20,000 feet, and cost $14 million each.