Eurocontrol Maastricht UAC [1] is the upper area air traffic control centre responsible for the European backbone air traffic over Belgium, Netherlands, Luxembourg and northern Germany.

The Controller Working Position (CWP) subsystem [2] deals with the interactive presentation of track, flightplan, conflict, coordination, weather and support data to the ATC controller.

As part of the Maastricht Fallback System (MFS), the Fallback CWP provides user interface functions that enable Air Traffic Controllers (ATCO), Supervisors (SUP) and Flight Data Specialists (FDS) to perform their respective tasks under fallback conditions (that is during a planned or unplanned outage of the primary ATC system).

Each Fallback CWP system receives plot, track, flightplan, conflict and status information from other MFS subsystems, processes them locally, and presents the information, in graphical or tabular format, onto the console monitor. The user is able to interact with the presented data by using the consoles mouse and/or the keyboard. Flightplan modifications are delivered to the Fallback Flight Server (FLB-FS) for distribution. Print requests are delivered to a Fallback printer.

The Fallback CWP also receives and processes time information and control commands from, and provides monitoring, status and logging information to, other MFS subsystems.

Fallback CWP systems are deployed into the consoles of every ATCO, FDS and central supervisory position within the Operational, Training and Test partitions. As part of the Fallback CWP subsytem, one Fallback CWP Target Software Server (TSS) is deployed into every partition, to facilitate the distribution of new software images onto the Fallback CWP systems.

Fallback CWP software images are created using Fallback CWP Target Generation Systems (TGS), of which a few are deployed within the development environment.

The Fallback CWP application, codecs, SNMP agents, system startup and process monitoring are nearly completely written in Tcl/Tk, with only a few modules (Track canvas item, UDP channel) in C.

The Fallback CWP has been designed by Sebastian Wangnick. Major implementation tasks have been performed by 42 Solutions (http://www.42solutions.nl).

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