(REUTERS) - The U.S. Federal Aviation Administration on Wednesday granted four more companies exemptions to use drones commercially, further opening the airspace to unmanned aircraft even as lawmakers raised questions about the risks.
Trimble Navigation Ltd, VDOS Global LLC, Clayco Inc and Woolpert Inc said in their petitions to the FAA that they would operate drones weighing less than 55 pounds (25 kg) and keep them within view at all times.
The approvals broaden the uses of commercial drones to include aerial surveying, construction site monitoring and oil rig flare stack inspections. Previous FAA exemptions were for aerial photography by seven television and film companies.
The FAA is expected to release a draft rule on drones by the end of December. The latest approvals came as the FAA and other industry officials were questioned by Congress on Wednesday about the safety and benefits of drone use.
The FAA has been under mounting pressure from companies seeking to employ drones to survey crops, inspect remote power lines and pipelines or deliver packages, or other uses.
The U.S. drone industry is expected to generate $13.6 billion in economic activity and create 70,000 jobs in the three years after commercial use restrictions are lifted, according to the Association for Unmanned Vehicle Systems International.
Capt. Lee Moak, president of the Air Line Pilots Association, brought a small quad-copter to a House aviation subcommittee hearing on Wednesday that he noted was capable of flying at 6,600 feet for 15 minutes.
"That means it could easily end up in the same airspace I occupy when I am on approach to land at Newark,Seattle, or any other airport," he said, noting increased reports of drone sightings by pilots.
He urged the FAA not to allow pressure to rapidly integrate drones into the national airspace and compromise safety.
But others pressed for much more rapid FAA action. Rep. Roger Williams, a Texas Republican, said Amazon.com has had difficulty getting FAA permission for outdoor tests of package delivery in Washington state. Amazon told the FAA this week it has begun testing outside the United States because of the restrictions.
The FAA's associate safety administrator, Peggy Gilligan, said the agency knows Amazon is unsatisfied and expects to "reach some conclusions shortly" on its application for an exemption.