The U.S. Office of Special Counsel OSC.L, which reviews whistleblower claims made by federal employees, outlined seven instances where the FAA FAA.L took as long as two years to respond to concerns brought by aviation employees.

The claims include allegations that air traffic controllers slept while on duty, allowed departing and incoming flights to come perilously close to one another and used dangerously imprecise language when directing aircraft, resulting in a near-crash, among other troubling practices.

There have been complaints going back to at least 2005 where the FAA has taken an extraordinarily long time to respond or had never really fully responded, Special Counsel Carolyn Lerner said at a news conference.

"These disclosures paint a picture of an agency with insufficient responsiveness given its critical public safety mission," Lerner said in a letter to President Barack Obama.

"Although the United States' aviation system is the safest in the world, the public properly expects zero tolerance for unnecessary risks."

The FAA experienced a number of embarrassing safety incidents last year. Hank Krakowski, the FAA official overseeing day-to-day U.S. air traffic operations, resigned last April after a series of disclosures of air controllers sleeping on the job.

Lerner noted that the FAA has one of the highest rates of whistleblower filings per employee of any executive branch agency. Since 2007, 178 had been filed, 87 of which related to aviation safety, the OSC said.

The OSC urged that the FAA adopt stronger oversight of air safety.

The FAA is part of the Department of Transportation, which said it has been working on the whistleblower cases brought forward by the OSC and would "take aggressive action where necessary."

"(The Department) takes all whistleblower complaints seriously ... We are confident that America's flying public is safe," it said in a statement.

Cases brought to light by FAA whistleblowers included air traffic controllers in New York found sleeping in control rooms, playing video games and being careless when communicating with pilots. In response, the FAA replaced the management team and disciplined three out of five managers.

Another complaint alleged that hundreds of emergency medical service helicopters in Renton, Washington, have been incorrectly retrofitted for night vision goggles, posing a possible threat to pilots' ability to read instruments.

(Reporting By Lily Kuo; editing by Christopher Wilson)

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