Both the U.S. Government Accountability Office and the National Transportation Safety Board have released reports signaling to the FAA that there are problems with the low numbers of controllers, scheduling, and controller fatigue, which will affect the overall job performance of the controllers. The U.S. GAO report to congressional headquarters on Aviation and Runway Safety declared that it is not possible to make sufficient headway with the runway safety concerns "until the human factors issues involving fatigue are addressed." The Union believes that the fatigue is the result of the decreased number of air traffic controllers, caused by the FAA's unilaterally enforced policies. They then defer this concern to the National Transportation Safety Board (NTSB), saying, "Air controller fatigue…continues to be a matter of concern for the NTSB."