(Reuters) - New procedures to better identify air traffic controller errors showed a jump in incidents of aircraft flying too close to each other in the skies over the United States, according to data released on Thursday.
There were 4,394 such instances for the year through September 30, 2012, more than double the level of the previous year, the Federal Aviation Administration said.
Of the total, 1,271 were termed "risk analysis events," or incidents serious enough to warrant further review because aircraft had flown more than 34 percent closer together than FAA regulations allow, and 41 were termed "high risk events."
The close calls, which in industry jargon are termed "loss of separation events," have since early 2012 been tracked by enhanced radar and a new software system.
The FAA has also instigated reporting procedures that encourage air traffic controllers to report incidents without fear of reprisal.
Some of the riskiest conditions for aircraft were said to be turns to final airport approach, parallel runway operations and aborted landings, known as go-arounds.
But none of the incidents resulted in a collision during nearly 133 million takeoffs and landings.
David Grizzle, FAA's chief operating officer, said in the just-released 2012 safety report that the changes were the most significant in 30 years as a way to track risk and safety performance in the U.S. airspace.
(Reporting by Susan Heavey and Ros Krasny; Editing by Phil Berlowitz)