Routine use of small drones by real estate agents, farmers, filmmakers and countless other commercial operators was cleared for takeoff by the Obama administration Tuesday, after years of struggling to write rules that would both protect public safety and free the benefits of a new technology.

The Federal Aviation Administration announced the creation of a new category of aviation rules designed specifically for drones weighing less than 55 pounds. The long-anticipated rules mean commercial operators can fly drones without special permission.

Industry and government officials describe commercial drones as the biggest game-changing technology in aviation since the advent of the jet engine.

“This is a watershed moment in how advanced technology can improve lives,” said Brendan Schulman, a vice president at DJI, the world’s largest civilian drone-maker.

Jason Miller, an Obama economic adviser, said the rules are the first step toward full integration of drones in the national airspace system.

Until now, commercial operators have had to apply for a waiver from rules that govern manned aircraft, a process that can be time-consuming and expensive.

Since 2014 the FAA has granted more than 6,100 waivers and another 7,600 are waiting for approval. Many more small companies have been using drones without FAA permission, say industry officials.

Unless those operators make a serious mistake that brings them to the FAA’s attention, there’s not a lot the agency can do to track them down. The new rules would provide an easier way for those businesses to operate legally.

The rules also would effectively lift the lid on flights by other potential operators who have held off using the technology — ranchers who want to count cattle, filmmakers who want to employ aerial photography, research scientists, companies that inspect infrastructure like bridges, oil platforms and smokestacks, to name a few.

Under the new rules, operators would register their drones online, pass an aviation knowledge exam for drone pilots at an FAA-approved testing center and then they’re approved. That’s a big change since operators currently have to have a manned aircraft pilot’s license.

The rules permit commercial transport of goods by drones for the first time, but the other restrictions on flights beyond sight of the operator and over people still apply.

Other important limitations also remain in place. Drone flights will be permitted only during the day and at twilight. Drone industry officials have long complained that restricting drone flights to daytime precluded a great many uses like some search and rescue operations, agricultural operations best done after dark and roof inspections of commercial building roofs that use heat sensors.

Operators could still seek waivers to restrictions like nighttime flights, flights beyond sight of the operator and flights over people.

The rules still prevent delivery drones from flying across cities and suburbs clasping small packages. Amazon and Google announced two years ago that they are working on drone delivery systems for goods purchased online, and Google officials have said they expect deliveries to begin sometime in 2017.

FAA Administrator Michael Huerta said the agency is researching how drone deliveries might safely be accomplished, but he declined to set a timetable for such rules.

What’s missing from the rules is an enforcement mechanism, said Sarah Kreps, a Cornell University professor. “It is hard to see how the (FAA) actually can ensure that these rules are followed,” she said.

Congress has been prodding the FAA for more than a decade to write rules to enable broad access to the national airspace by civilian drones. Initially, the agency put its emphasis on finding ways to enable larger drones like those used for military missions to safely fly at the same altitudes as airliners and other manned aircraft. After several years, the agency shifted its focus to small drones when it became clear that the market for their uses was developing much faster.

But the FAA’s slow pace led frustrated lawmakers to include a provision in a major aviation bill four years ago setting deadlines for the agency to issue regulations to integrate safely small drones into the national airspace by August 2014 and other drones by September 2015.

The new rules fulfill that first deadline. The agency is also working on an array of other safety rules and standards to further broaden the circumstances under which drones can be flown. In April, FAA officials said they are working on regulations that would permit some commercial drones to fly over people and crowds based on recommendations from an industry advisory committee.

The flexible revisions and clarification of provisions will put U.S. companies on the global market, said Chris Walach, director for the FAA-designated Nevada Unmanned Aviation Test Site and director of technical operations for the Nevada Institute of Autonomous Systems.

“It’s going to help the commercial UAS companies better execute their missions and be more competitive,” Walach said. “This allows them to be more competitive and actually go after those jobs they weren’t able to go after before.”

He said the 624-page document relaxes and clarifies provisions for unmanned aviation systems. At the Nevada test site, one of six across the country, he said they’ll be able to take companies and vendors closer to the next level of integrating drones into national airspace.

“No doubt there is going to be some adjustments we’re going to have to make as a test site for implementation for the (Part) 107,” he said, referring to the document, but: “I see those adjustments as being very positive.”

U.S. Rep. Dina Titus, D-Nev., serves on the House of Representatives Aviation Committee, which has jurisdiction over the FAA. She said in a statement that she’ll work with manufacturers, operators, developers and regulatory agencies to progress commercial use of unmanned aviation systems.

“This rule is a significant step forward for an industry that has the potential to transform our economy in Nevada and nationwide,” she said.