Approach control is located in the Bloc Technique Operationel (BTO) but has no outside view on the runway. The approach controller operates mostly in a class C/D airspace called Terminal Control Area (TMA) which extends from an altitude of 2500 feet to an upper limit of flight level 145/165. Even though the TMA boundary is a bit larger than Luxembourg territory itself it is still pretty small by international standards.
The aim of the approach controller is to efficiently vector arriving aircraft to establish safely on the Instrument Landing System (ILS) by giving heading and flight level/altitude restrictions. All arriving and departing IFR aircraft must be radar separated by 5 nautical miles horizontal or 1000 feet vertical from each other. Except for traffic reasons, all departing flights adhere to a Standard Instrument Departure route (SID) that will lead them to their requested airway.
Secondary radar (mode S) is used to obtain callsign, level and speed readouts on the radar display but in class D airspace, separation is applied only between IFR traffic (Instrument Flight Rules), but not between VFR (Visual Flight Rules) traffic and IFR traffic. Only traffic information is given when applicable.