Before you even taxi to the runway, you receive a routing clearance (also called a clearance, or in English, "clearance to leave the CTR via..."). This clearance is crucial: it gives you permission to operate inside the control zone after takeoff. Without it, you cannot legally depart.
The instruction to leave the CTR /strong> – "Leave Control Zone
The route or sector – A specific direction or navigation point (e.g., "via Sector South," "via waypoint Klosterneuburg")
The altitude – A specific flight level or altitude limit (e.g., "at 2,500 feet")
Additional information – Wind, QNHtransponder code (squawk), or runway assignment
You receive this clearance normally while you are taxiing, before you reach the holding point. The routing clearancedoes not give you permission to use the runway. It only permits you to fly inside the CTR once you are airborne. This is an important distinction that catches many students.
When the tower gives you a routing clearance, you must read it back word-for-word. Include wind, QNH, squawk code, and runway in your readback. When you have read it back correctly, the controller will typically acknowledge with "correct" or simply remain silent (silence means agreement).