The test requires judgments on spatial relationships and requires application of the rules and procedures contained in the Air Traffic Control Handbook. Based on aptitude and test scores, trainees are selected to work at either an enroute center or a tower. After graduation, it takes several years of progressively more responsible work experience, interspersed with considerable classroom instruction and independent study, to become a fully qualified controller. Controllers must pass a physical examination each year and a job performance examination twice each year. Failure to become certified in any position at a facility within a specified time may also result in dismissal.
Controllers also are subject to drug screening as a condition of continuing employment.
At airports, new controllers begin by supplying pilots with basic flight data and airport information. They then advance to ground controller, then local controller, departure controller, and finally, arrival controller. At an enroute traffic control center, new controllers first deliver printed flight plans to teams, gradually advancing to radar associate controller and then radar controller. However, there are only limited opportunities for a controller to switch from a position in an enroute center to a tower. Turnover is very low because of the relatively high pay and liberal retirement benefits, and controllers have a very strong attachment to the occupation.