Plan for the Future: 10-Year Strategy for the Air Traffic Control Workforce, 2009-2018 [open pdf - 9MB]
"Air traffic controller workload and traffic volume are dynamic and so are staffing needs. One of the primary factors affecting controller workload is the demand created by air traffic. This means that an adequate number of controllers must be available to cover the peaks in traffic caused by weather and daily, weekly or seasonal variations. FAA [Federal Aviation Administration] continues to 'staff to traffic.' This practice exercises the flexibility to match the number of controllers at each facility with traffic volume and workload. System-wide, traffic has declined by about 17 percent since 2000. […] The FAA has demonstrated over the past several years that it can effectively manage the long predicted wave of expected controller retirements from the controllers that were hired as a result of the controller strike of 1981. For example, in 2005, the FAA began hiring again in anticipation of the retirements expected this decade. That year, the agency began hiring more controllers than the number that retired each year, in order to make sure enough trained controllers were on board when the retirement wave began to swell. As veteran controllers retire, controllers hired since 2005 are completing training and are replacing retirees as Certified Professional Controllers (CPCs). Similarly, controllers hired in the 1990s may move from mid-level facilities into the higher-paying, higher-workload facilities. The transition through the ranks will continue to provide increased career growth opportunities for the workforce. The current hiring plan has been designed to phase-in new hires as needed. This will avoid another major spike in retirement eligibility like the current one experienced as a result of the 1981 controller strike."
Federal Aviation Administration: http://www.faa.gov