The number of aircraft near misses more than doubled last year , but U.S. aviation officials tied the increase to new systems that report mistakes not caught previously . There were 4,394 cases in which planes came too close to one another in the year ending September 1 , 2012 -- up from 1,895 the year before , the Federal Aviation Administration said on Thursday . Forty-one events were characterized as `` high-risk events . '' None resulted in accidents . The FAA had predicted an increase as it phased in a program to monitor radar and automatically report problems . The agency says it is a victim of its own success . With commercial aircraft accidents rare -- or non-existent in some recent years -- it is difficult to use accident data to identify trends . So the FAA has placed a greater emphasis on looking at `` precursors '' to accidents , such as `` loss of separation '' events in which aircraft come closer together than intended . `` We are covering electronically and identifying things that we never did before , '' said one FAA official , speaking on condition of anonymity . The 4,394 `` losses of separation '' in 2012 occurred during 132 million take-offs and landings . Put another way , that 's 3.3 incidents per 100,000 operations , the FAA said . `` If you want a measure of safety , that 's the number , '' the official said . FAA has various separation standards , depending on air space and aircraft . At high altitudes , planes should be separated by at least five miles horizontally or 1,000 feet vertically . Nearer to airports , planes can be closer together . The agency said it has worked with its workforce and the controllers ' union to change the safety culture of the agency -- emphasizing collection of data over punishment . Under the new non-punitive reporting system , controllers are encouraged to voluntarily report mistakes and problems . It has buttressed that with an automated system that monitors air traffic , reporting problems to headquarters without any influence from the local facility . As a result of five different reporting systems , the number of reports grew 10-fold in 2012 . Officials said the new system makes comparisons with previous years misleading . Information collected in 2012 and 2013 will create a new baseline for meaningful comparisons in the future . Of the 4,394 `` loss of separation '' incidents , the FAA said 1,271 involved cases where the planes came 34 percent closer than allowed . Of those , it characterized 1,048 as `` low risk '' events , 182 as `` medium risk , '' and 41 as `` high risk . ''
FAA says year-over-year increase due to better reporting . Comment: New program monitors radar and automatically reports problems .