The expansion is driven by technological advances that have made them smaller, more sophisticated and cheaper, and new federal aviation rules that will open the skies to an array of drones by late 2015.
Robotic aircraft promise great advances in everything from humanitarian relief and environmental protection to news gathering and real-estate marketing, industry champions say.
In Arizona, UAVs have already been used for firefighting and crop management and are being tested for search-and-rescue missions. Elsewhere, they're being deployed to shoot video for television news and conduct law-enforcement surveillance.
"We're not talking about next-generation. We're talking the next five years," said Raynald Bedard, an associate professor at Embry-Riddle Aeronautical University's Prescott campus, where students are preparing for careers in unmanned aviation.
Arizona hopes to lead the trend, wanting a piece of an industry expected to nearly double in size this decade. Worldwide sales are projected to balloon from $6.6 billion this year to $11.4 billion by 2020, according to defense-industry analysts at the Teal Group in Virginia. The state this month will bid to become one of six federal test sites for expanded, non-military use of drones.
But as with many evolving and potentially intrusive technologies, the civilian drone invasion won't arrive without controversy or questions about its impact on privacy and safety.
With the introduction of thousands of unmanned aircraft, many too small to be detected by radar, Federal Aviation Administration rules will be critical in reducing chances of midair collisions.
Civil libertarians warn that anything that can be flown by a law-abiding person can also be used by a drug smuggler, terrorist or Peeping Tom. In the hands of an unscrupulous journalist or law- enforcement officer, the snooping possibilities are chilling, they say.
Chad Black, a professional photographer in Flagstaff, quickly recognized the usefulness and the less-welcome possibilities of UAVs after his purchase in April of a Parrot AR Drone, a remote-controlled helicopter that Apple Inc. sells for $300.
Within 15 minutes of arriving home, he was flying the craft over his house and filming the San Francisco Peaks, using his iPad to control the device. "I wanted a way to take aerial photographs," said Black, 33.
When he posted flight footage on YouTube, the U.S. Forest Service called him, curious about the possibility of using drones to monitor the health of forests or watch for wildfires.
Black also flew the drone over a Phoenix neighborhood where he has a second home, and he had a sudden realization: "You could see my neighbors swimming in their pool. If that were me, I would feel violated," he said.
Innovating with drones
Arizona has a long history of research and innovation in unmanned flight.
The state is home to key military bases, test sites and defense contractors that have been active in robotic flight for years. As those technologies and industries have matured, they have spun off startup companies that capitalize on the available labs, airspace and expertise.
Brock Technologies of Tucson is among them. Keith and Jessica Brock left Raytheon Corp. in 2007 to advance the company they had founded a couple of years earlier.
The company, which makes drones for government and military use, has 13 employees and sales that have doubled every year, Keith Brock said. He said he couldn't divulge specifics because the government prohibits it. The Brocks' niche is custom contracts to solve specific problems rather than UAVs that can be mass-marketed.
"In unmanned aviation, technology changes as rapidly as computers. In two months, it can be out-of-date," Brock said.
The Brocks were engineering students when in 2003 they mounted a Maricopa Agricultural Center camera on their test aircraft as part of a University of Arizona experiment. The drone measured moisture in plants. With that information, farmers could adjust their irrigation and get bigger yields. The farmers also experimented with his UAVs for crop dusting, an emerging use in some countries with less-stringent laws.
Among the Brocks' ideas for new drone capabilities was to help wildland firefighters, infantry or emergency-rescue teams reach remote places without arriving fatigued from carrying heavy gear. A UAV could carry their gear.
Other unmanned vehicles have already been used to help fight wildfires. Last year, as the Monument Fire raged near Sierra Vista, the Bureau of Land Management asked the Department of Homeland Security to fly border-surveillance missions over the flames.
"They could fly where big aircraft couldn't," said Dolores Garcia, BLM's fire-management supervisor in Arizona. "Using infrared capability, they can give us the size of the fire."
Because it was unmanned, the UAV also could fly at night, which conventional firefighting aircraft can't do for safety reasons. The U.S. Forest Service is asking the FAA to authorize the use of more drones for fire missions, Garcia said.
The Brocks also have successfully tested a vehicle capable of tracking a car. After the operator captures an image of the target, technology allows the drone to recognize it. After that, the drone does the rest. A company video shows the device tracking the car through winding streets.
"It follows you like a lovesick puppy," Keith Brock said.
He said he hadn't thought of the implications for surveillance, but such capabilities heighten the concerns among those who see the technology advancing far faster than privacy laws and other safeguards.
A drone that can follow a firefighting or rescue vehicle also could tail a girlfriend's or spouse's car, or a business or political competitor.
Many in the industry are aware of the snooping stigma that comes with their products, but also say the fears are inflated. The same potential for abuse exists for other aircraft, from ultralights to helicopters and small fixed-wing airplanes, said Paul Nelepovitz, Arizona chapter president of the Association for Unmanned Vehicle Systems International, an industry lobbying group. The industry has released a code of conduct and touts its goal of thorough training.
Brock thinks the courts will settle things.
"The people who are serious will have the budget, discipline and maturity to fly and develop these properly," he said. "The rules will be based on liability."
He's more focused on creating machines that can save lives. He's been testing a system that flies two UAVs joined together, similar to the method used to transport the space shuttle using a jumbo jet. Once the "mother ship" drone locates a search-and-rescue victim using cameras and GPS, it orders the smaller plane to detach.
That smaller craft then uses GPS to pinpoint the victim and release lifesaving supplies. The smaller drone is disposable because it might have to be abandoned in treacherous terrain.
"They (UAVs) are for the dull, dangerous and dirty jobs," Nelepovitz said. "The demand is there, and the market is huge."
Arizona's drone bid
Arizona hopes to cash in on the anticipated drone bonanza.
By late this month, the federal government will solicit proposals from applicants seeking to host one of six national test sites, where researchers will figure out how to make safe, integrated flight in the civil airspace a reality. About 30 other states are vying for the selection in December.
Arizona appears well-positioned. The state's varied climate and terrain are ideal for testing aviation systems. Also, its long history and strong presence of defense contractors and drone training mean top UAV experts are already here.
Fort Huachuca in southern Arizona is the nation's main training center for operators who fly missions over war zones in Iraq and Afghanistan and over terrorist hotbeds in Pakistan and Yemen. More than 10,000 operators have graduated from its program in the last decade. Patrols along the U.S.-Mexican border originate there, too.
"Arizona has an amazing opportunity because we've done so much training and testing over the last decade and we have such phenomenal weather," said Robin Sobotta, Business Department chair at Embry-Riddle Aeronautical University's Prescott campus.
An emerging plus for Arizona is academia. Arizona State University, the University of Arizona and Embry-Riddle are developing new curricula to train UAV operators, designers and data analysts.
The industry predicts demand for UAVs will create 23,000 jobs nationally by 2025.
At Embry-Riddle, associate professor Raynald Bedard saw an opportunity.
The aviation college's Florida campus focuses on large drone aircraft, such as the Predator, best known for carrying guided missiles to kill suspected terrorists.
But with small affordable UAVs set to flood the market, Bedard saw a need to train people to fly for civilian purposes.
He now has a dozen students.
In the fall, Bedard will launch a program for students to learn robotics, mission planning, data analysis and entrepreneurship.
At ASU, Mitzi Montoya, vice provost and dean of the College of Technology and Innovation, has similar aspirations. In the fall, the first series of classes in the UAV discipline will begin for junior-level aviation or engineering students.
"Our goal is to have in two years a full-fledged program," Montoya said. "Not a large number of universities are doing this -- fewer than five."
In Tucson, students under assistant professor Ricardo Sanfelice design and experiment on unmanned aircraft and robotic-controls systems in his lab at UA's Department of Aerospace and Mechanical Engineering.
He's been researching collision-avoidance systems on ground vehicles. Now he is trying to develop software that can predict the motions of multiple objects. Such endeavors may play a role in answering how the FAA can roll out collision-avoidance systems on drones and, later, all aircraft.
The privacy question
Not everyone is eager to rush into the new frontier of robotic flight.
A poll last month showed 42 percent of Americans were "very concerned" about their privacy if law-enforcement agencies use drones with high-tech cameras. Researchers at Monmouth University found strong support for drones' use in search-and-rescue missions, tracking fugitive criminals and controlling illegal immigration, but strong opposition to using them to issue speeding tickets.
Among those sounding privacy alarms are the Electronic Privacy Information Center in Washington, D.C., the Electronic Frontier Foundation in San Francisco and the American Civil Liberties Union.
While acknowledging the benefits of emergency-response drones, the ACLU said in a December report, "Interest in deploying drones among police departments is increasing, and our privacy laws are not strong enough to ensure that the new technology will be used responsibly." It warned that once law-enforcement agencies acquire drones, they'll be tempted to use them for unauthorized surveillance.
The group cited an example in which the Houston Police Department got special permission to fly a UAV that stayed aloft 24 hours. In 2007, the department told a local television-news team that it wouldn't rule out using drones for traffic enforcement.
In New York City, a couple having sex on a private rooftop balcony were filmed by a conventional police-helicopter team in 2004 using night-vision equipment, the ACLU noted.
The ACLU warned of the potential of widespread intrusion into daily life. Among the concerns were UAVs with night-vision equipment, emerging technology that can "see through" walls, and video analytics that can track individuals using facial-recognition software. Video also can be streamed on the Web live, drone pilots say.
The ACLU also warned of racial or other profiling and automated enforcement similar to highway photo-enforcement. It noted the government claims the power to follow the movements of citizens using GPS systems.
The ACLU did not delve into misuse of drones by individuals. But with the technology becoming more affordable and advanced, it's easy to conjure up intrusive scenarios: a sexual predator using a drone to stalk victims; a homeowners association official spying on neighbors.
"These vehicles are like flying robotic video cameras: They're small, cheap and portable and allow for pervasive surveillance in ways that aren't possible with helicopters," said Alessandra Soler, executive director of the ACLU of Arizona. "Without adequate rules limiting fishing expeditions, especially by police, people's privacy rights are seriously at risk."
Aviation-safety experts also envision troublesome scenarios.
The accident rate among drones is seven times that of general aviation and more than 350 times higher than commercial aviation, FAA officials said in testimony before Congress in 2010. They often fly in dangerous environments or are experimental aircraft, but the safety record "warrants careful review" before drones can be integrated, the agency warned lawmakers.
The Aircraft Owners and Pilots Association, which represents the general-aviation community, agrees. "This is very uncharted territory because there is no pilot on board to operate see-and-avoid procedures," said Heidi Williams, the association's vice president for airspace issues.
Williams and others said specific concerns won't be known until the government issues its proposed rules. But considering some drones can be hand-launched and some are smaller than a human hand, it's easy to see why pilots worry about crowded skies. Small but dangerous objects, like geese, can't be detected by radar.
For now, the FAA tries to keep skies safe by separating aircraft and restricting airspace to keep small private aircraft away from jetliners' flight paths. Midair collisions are extremely rare. The last such U.S. crash involving a commercial passenger flight was in 1990. The same separation rules limit where drones can fly.
But in the future, when thousands more UAVs take to the skies, some operated by amateurs who are unaware of the rules, safety risks will increase.
The FAA wants to develop collision-avoidance systems for drones as a step toward equipping all commercial flights with sense-and-avoid technology by the end of the decade.
Research labs like UA's are already working on the issue. And if Arizona becomes a federal test center, the state could play a large role in how the future of drones unfolds.