U.S. aviation regulators approved commercial drone applications so quickly in recent years that they missed safety violations and took few enforcement actions, a government watchdog report concluded.

The Federal Aviation Administration over a two-year span granted more than 5,500 exemptions allowing unmanned flights by businesses, but offered only limited training for its safety inspectors to deal with the deluge of new operators, the Transportation Department’s inspector general found in a report released Tuesday.

In one case, an FAA office failed for four months to notify field investigators of reports that a drone was being flown at night, which was prohibited. Another drone operator who was flying within the five-mile no-fly zone near an airport told the FAA he was unaware of the rules and hadn’t read his exemption.

“FAA also lacks a robust data reporting and tracking system for” drone activity and “the information available is difficult to analyze and collected in a fragmented manner throughout the agency,” Assistant Inspector General Matthew Hampton wrote in the report.

The report is the latest indication of how the rapid expansion of civilian drone usage that spurred more than 500,000 people to register unmanned aircraft in the last year has tested the aviation system. In recent years, reported safety incidents involving drones reached more than 100 per month.

Recreational Drones

Under a 2012 law, Congress authorized the FAA to grant exemptions allowing commercial unmanned flights — mostly for aircraft weighing less than 55 pounds (25 kilograms). The program was designed to allow businesses to begin using drones while the agency wrote formal regulations allowing such flights for hire. Those went into effect on Aug. 29.

Even though many businesses had already begun flying drones without government approval, the law at the time limited their use almost exclusively to recreational users.

The first approvals were granted in September 2014 to seven filmmakers. Approvals began slowly and the FAA placed strict restrictions on flights. As time went on, the agency set up a process to allow easier approvals for companies willing to stay within 200 feet of the ground and to restrict use to purposes already approved, such as photography that wasn’t near bystanders.

The agency eventually granted 5,552 of the drone exemptions as of Sept. 28, according to its website.

Moving Quickly

The agency was moving so quickly it didn’t check whether applicants had pilots’ licenses, according to the report. It also didn’t track where applicants were operating, making it difficult to inspect them.

At the same time, the FAA was slow to educate its inspectors, some of whom “expressed their frustration” at the lack of training they’d received, the report said.

The agency has focused on trying to educate wayward drone operators rather than opening enforcement cases. Up until April, the agency had issued 625 “education letters” to drone users, while only seeking enforcement actions against 30.

The FAA, in a written response to the report, said it agreed with the report’s six recommendations. The agency has made “significant progress” in making drone flight safer, it said in the response.

It has taken numerous steps to improve compliance with drone rules, including adding new training for its inspectors and requiring a drone knowledge test for commercial operators.

The current regulations allow for more activities, such as flying closer to people as long as it’s not directly over them. The agency is also drafting rules for allowing some types of drones to fly over people if the aircraft are designed so they won’t hurt anyone in a collision and it’s also working with companies to test longer-range drones that can fly out of the operator’s sight.