U.S. regulators are increasing enforcement and trying to educate drone pilots to minimize risks to commercial traffic posed by the small unmanned aircraft, the nation’s aviation chief said.

The people flying drones don’t usually have the same level of training as pilots who’ve spent hundreds of hours learning aviation rules, Federal Aviation Administration chief Michael Huerta said today on CNN.

“That is certainly a serious concern,” Huerta said. “That’s why we are very focused on education. That’s why we’re also focused on enforcement.”

The FAA has logged 193 incidents in which traditional pilots reported unmanned aircraft flying too close or drones were spotted flying over crowds, such as at sporting events. The incidents rose from fewer than 10 per month in March and April to 41 cases in both September and October, according to data the agency released Nov. 26.

“These are very high performance aircraft and they are difficult to see,” Huerta said of drones. “This is one of the big challenges and so that’s why the rules require that people stay away from airports.”

The FAA allows recreational use of drones as long as operators follow guidelines set by hobby groups, such as staying below 400 feet (123 meters) above the ground.

The FAA hasn’t approved drone flights for commercial purposes, except for an exemption granted to six Hollywood movie makers and two oil companies in the Arctic region of Alaska. A proposed rule allowing commercial flights is scheduled to be revealed by the end of the year.