Air Traffic Controllers are people trained to maintain the safe flow of air traffic in the global air traffic control system. Air traffic Controllers apply many rules to keep aircraft at a safe distance from each other in their area of responsibility and move all aircraft safely and efficiently through their assigned sector of airspace, as well as on the ground by forwarding recommendations, information and instructions to pilots by means of radiotelephony, cooperating with several assisting divisions and utilizing technological developments.
For instance; any aircraft to perform flight from Ankara to Istanbul may not take off and fly at any time. The aircraft is required to fly on the pre-determined air routes and comply with the instructions provided by the air traffic controllers. Therefore, the pilots are required to obtain clearance and instructions from the air traffic controllers regarding the matters ranging from engine start up clearance, take-off, flight in airspace, flight level to climb or descend, speed adjustments, landing and ground movements of aircraft. A single air traffic controller may be responsible for many aircrafts simultaneously.
While duties of air traffic controllers vary depending on the positions of area, approach and aerodrome controllers, primary duties thereof are as follows:

• To ensure safety above all else
• To give climb or descend instructions and vectors to keep safe, orderly and rapid flow.
• To separate aircrafts from other aircrafts, obstructions and ground vehicles.
• To provide all information to aircrafts like weather conditions, expected approach procedure etc.
• To handle unexpected events, unscheduled traffic and emergencies including handling coordination with search and rescue units.