Preamble

Coordination is indispensable in the overall air traffic control system. This is particularly important in a highly complex airspace such as that over the Federal Republic of Germany with its numerous small sectors. There are a large number of problems that cannot be solved within one's own sector and must therefore be solved in cooperation with neighboring sectors. The basis for coordination between the different sectors is provided by the various operating agreements and letters of agreement (LoA). For many of the standard flight movements, conditions for the handover of aircraft at sector boundaries can be found there. For various reasons, however, it is often necessary to deviate from the standard agreed in the documents. Here, coordination with neighboring sectors is required. In real air traffic control, almost every center and approach workstation has a so-called coordination controller or planner whose tasks include making phone calls to neighboring sectors and thus coordinating the sectors with each other.

In air traffic control, the principle "the receiving unit states the conditions" applies, meaning that the receiving sector determines the conditions under which the aircraft must fly in. In extreme cases, this also means that if in a fictitious sector sequence "A-B", controller B requires all aircraft to enter his sector "at FL100, speed 220, DCT <WPT>", sector A must implement this sequence.

This does not mean that individual or general renegotiation is not possible or that sector A should overflow. Nevertheless, this principle applies and, with common sense, this is not an invitation to a bazaar.

Therefore, it should be noted that the more extreme the condition you impose on the previous sector, the sooner you should let them know, if possible. It's all a matter of communication and pre-planning.
Use your head and common sense, think outside the box and communicate sensibly and realistically with each other.