WASHINGTON -- It came from the sky.
One moment, Eileen Peskoff was enjoying a hot dog after running with the bulls at a Petersburg, Va., racetrack. Then she was on her back, knocked down when a 4-foot drone filming the event in August lost control and dove into the grandstands where she was sitting.
"You sign up for something called running the bulls, you think the only thing you'll get hurt by is a 1,200-pound bull, not a drone," Ms. Peskoff said.
Drones flown for a business purpose, like the one that left Ms. Peskoff and two friends with bruises, are prohibited in the United States. That hasn't stopped an invasion of flights far beyond the policing ability of the Federal Aviation Administration, which since 2007 hasn't permitted commercial drones in the U.S. while it labors to write rules to allow them.
Drones have nonetheless been used to film scenes in the Martin Scorsese-directed movie "The Wolf of Wall Street" and sporting events for Walt Disney Co.'s ESPN. They've inspected oilfield equipment, mapped agricultural land, and photographed homes and neighborhoods for real estate marketing, according to industry officials, company websites and videos on the Internet.
All such flights in the U.S. are outside the rules. While the FAA hasn't ruled out granting commercial-use permits under limited circumstances, it has so far only allowed operations in the Arctic.
Some operators plead ignorance of the rules. Some say their flying is legal under exemptions for hobbyists. Using drones is so lucrative for Hollywood that they're flown knowing they're illegal, said one operator who declined to be identified.
The FAA is aware the number of flights is increasing and tells users to stop when it learns about them, it said in an emailed response to questions. The agency said it's considering new guidance on what's permitted.
For every time the FAA orders an operator to stand down -- as it did after a Michigan florist did a test delivery by drone Feb. 8, and in January with Lakemaid Beer, which posted a video online proposing 12-pack deliveries to Minnesota ice fishermen -- untold others fly below the radar, said Patrick Egan, a Sacramento, Calif.-based author and producer of an annual unmanned aircraft expo in San Francisco.
Small drones available on the Internet or at hobby stores for less than $1,000 -- some equipped with high-definition cameras like those made by San Mateo, Calif.-based GoPro Inc. -- are flooding the U.S. and being used by tens of thousands of people, whether legal or not, Mr. Egan said.
The FBI opened an investigation on March 4 after pilots on an Alitalia Boeing 777 nearing New York's John F. Kennedy International Airport spotted a multirotor copter that came within about 200 feet.
At least six other pilots, including a crew on another airliner, have reported close calls since September 2011 with what they believed were small unmanned aircraft like those favored by hobbyists, cinematographers and other businesses, according to NASA's Aviation Safety Reporting System, which logs safety issues.
While the government needs to do more to control the growth in drones, it has been "swamped" by political cross-currents and budget cuts that have made it difficult to craft rules, Doug Davis, who ran the FAA's unmanned aircraft office in the mid-2000s, said in an interview.
As airline pilot unions call for strict standards on the qualifications of drone operators, industry advocates including Mr. Egan say the standards should be eased. Lawmakers such as Sen. Dianne Feinstein, a California Democrat who said protesters flew toy drones outside her house last year, have pressed the FAA to add privacy requirements as it crafts safety rules.
"The FAA is going to have to step up the enforcement of people who use these things," said Sean Cassidy, national safety coordinator for the Air Line Pilots Association. ALPA is the largest pilots union in North America.
The FAA conducted 17 enforcement actions for illegal drone use in the 13 months that ended in July 2013, according to agency data that doesn't include informal steps like phone calls. It has issued one fine, which is being contested.
The FAA, set up to enforce manned aviation, doesn't have the resources to enforce existing rules on a new form of flying that isn't tied to airports and requires so little training almost anyone can do it, Mr. Davis said.
"The reality is there is no way to patrol it," Mr. Davis said. "There's just no way."
Some businesses flying drones make little attempt to hide what they're doing.
Freefly Cinema, an aerial photography company in Los Angeles and Seattle, has photos on its website of helicopter drones it says it flew to film scenes for "The Wolf of Wall Street" and a commercial for Honda.
A Freefly drone shot footage for a documentary about the Civil War battle at Gettysburg, Pa., that aired on most Public Broadcasting Service stations in November, the filmmaker, Jake Boritt, said.
Mr. Boritt said he got permission to film from the National Park Service. "It's not something that we did a whole lot of research into." he said.
The park service, which controls access to the Gettysburg site and not the airspace, didn't check with FAA about aviation regulations, Katie Lawhon, a spokeswoman, said in an email.
For Hollywood, the benefits of using drones are worth the miniscule risk of being caught, said an operator who films scenes for TV shows and commercials. He asked to be unidentified because the practice isn't permitted.
An unmanned aircraft system costing a few thousand dollars or less can replace dollies, booms and stabilization equipment costing tens of thousands, this operator said.
Drone advocates like Mr. Egan and the Association for Unmanned Vehicle Systems International, an Arlington, Va.-based trade group, said the FAA's drone standards are vague and helped lead to the explosion of users pushing the envelope.
The FAA had planned to propose rules by 2011 allowing commercial flights with drones weighing less than 55 pounds. The agency now doesn't expect to unveil the proposal until November.
The agency also isn't expected to meet a Congress-imposed deadline to craft rules for safely integrating unmanned aircraft into the nation's airspace by 2015, the Transportation Department's inspector general said in a report Feb. 5.