Washington (CNN) -- Unmanned aircraft patrolling the nation's borders have an accident rate seven times greater than general aviation aircraft, and hundreds of times greater than the rate of jetliners, federal officials said Thursday in urging caution in expanding the use of pilotless planes.
Unmanned aerial vehicles, or UAVs, have proven remarkably useful in the skies over Iraq and Afghanistan, but are difficult to integrate into U.S. skies, the most complex airspace in the world, FAA official Nancy Kalinowski said in testimony before a House Homeland Security subcommittee.
Kalinowski said the accident rates for Customs and Border Protection (CBP) aircraft are based on a relatively limited use of the planes -- only 5,688 flight hours. But because of the limited data, "the FAA must make conservative decisions" concerning integrating UAVs into U.S. skies, Kalinowski said.
It is the FAA's responsibility to ensure the safety of other planes in the sky as well as people on the ground, she said.
Increasingly, government agencies, police departments and private businesses have pushed the FAA for expanded use of UAVs. CBP currently operates six UAVs and will get a seventh by the end of the year.
The CBP accident rate is 52.7 accidents per 100,000 flight hours, Kalinowski said. The accident rate for general aviation aircraft is 7.11 accidents per 100,000 flight hours, and 0.149 accidents for commercial aircraft.
Public operators of UAVs such as the government and universities must obtain a special FAA certificate of waiver or authorization before operating in U.S. civil airspace. Civil users can get permits for research and development, demonstrations and crew training, but commercial UAV operations are not permitted at this time.