The Federal Aviation Administration has proposed a regulation that would place limits on commercial use of airborne drones, a technology that has sparked interest from surveying firms and construction contractors.

FAA last December had granted a handful of firms exemptions to use drones for aerial surveying and monitoring construction sites.

But FAA's eagerly awaited proposal, announced on Feb. 15, would be much more wide-ranging. It would apply to commercial use of small unmanned aircraft systems (UAS) weighing less than 55 lbs.

It also would restrict drones flights to daylight hours and requires that their operators keep the devices, also called unmanned aerial vehicles, or UAVs, within their line of sight. (FAA summary of proposal.)

Drones’ maximum altitude would be set at 500 ft and their top speed would be 100 mph. Under the proposal, the minimum age for UAS operators would be 17 years. Operators also would have to pass an aeronautical knowledge test and get an FAA certificate.

FAA’s plan doesn’t cover “micro” drones, which weigh less than 4.4 lbs; nor does it apply to model-aircraft. The agency will take public comments on its proposal for 60 days after it is published in the Federal Register.

FAA on Dec. 10 approved exemptions for four companies to use drones for aerial surveying, construction-site monitoring and inspections of oil-rig flare stacks. Exemptions were granted to Trimble Navigation Ltd., Sunnyvale, Calif.; VDOS Global LLC, Corvallis, Ore.; Clayco Inc., Chicago; and Woolpert Inc., Dayton, Ohio.

House Transportation and Infrastructure Committee Chairman Bill Shuster (R-Pa.) called FAA’s newly proposed regulation “a positive first step.” He added, “We need to properly balance safety, privacy and access while ensuring the United States remains at the forefront of aviation technology.”