Citing safety concerns and privacy issues, the Federal Aviation Administration (FAA) has delayed the selection of U.S. sites for the testing of unmanned aircraft, effectively putting the brakes on a push to integrate UAVs into civil airspace.

Congress had mandated that by the end of 2012, the FAA designate six UAS test sites to provide data to safely integrate UAS into the nation’s airspace by 2015. Arizona is one of 35 of states that want to be one of those six test sites.

In a letter to Republican Congressman Howard McKeon of California, chairman of the House Unmanned Systems Caucus, FAA Administrator Michael Huerta said the establishment of six test sites for UAV for experimentation has been suspended indefinitely.

“Our target was to have six test sites by the end of 2012,” Huerta wrote in the letter. “However, increasing the use of UAS in our airspace also raises privacy issues, and these issues will need to be addressed as unmanned aircraft are safely integrated.”

Members of Congress in states where unmanned arial systems are built bristled at news of the delay, and in particular the FAA’s contention that it was moving to protect privacy, which they said has never been a part of the agency’s mandate.

UAV testing was included in the FAA’s latest reauthorization, the Congressional legislation that funds the agency. The same legislation commits the FAA to establishing rules to integrate small UAVs by 2015.

“The FAA will complete its statutory obligations to integrate UAS into the national airspace as quickly and efficiently as possible,” Huerta’s letter states. “However, we must fulfill those obligations in a thoughtful, prudent manner that ensures safety, addresses privacy issues, and promotes economic growth.”