FAA data indicates that a very small number of ATC “operational errors” (a reduction in standard separation distances) occur in any given year (about 6.7 errors per one million operations, on average), but the General Accounting Office has little faith that the data is accurate. In a September 23 report to Congress, the GAO believes the statistics have several limitations, not the least of which is that all incidents might not be reported since it is the air traffic controllers themselves who are one of the main sources of the data. Also, due to the way data is recorded, the severity of many errors cannot be determined or is misleading.