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Enhanced Tactical Flow Management System - Background |
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When the CFMU started its operations, the ATFM service was supported by the TACT system primarily for use in the ATFM 'Tactical' operations (day of flight) but also for a large part of the 'Pre-tactical' operations (from 1-6 days prior airborne).
This system had two main functions:
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- the calculation of the traffic demand in every sector of concern within the CFMU area, using the flight plan information received from the Aircraft Operators (AOs) via the Initial Flight Plan Processing System (IFPS)
- the complex slot list calculation, allocation and distribution to the involved parties (ATC, AOs etc). This part of the system is called CASA (Computer Assisted Slot Allocation)
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The main purpose of the TACT system was to compare the traffic demand with the available ATC (sector) capacity. In cases where demand exceeded the ATC sector capacity, the system would make the information available to the Flow Management Controllers within the CFMU as well as their Flow Management Position (FMP) colleagues in the various ACCs. Together they would decide whether or not to implement a 'regulation', delaying flights through the allocation of a departure slot and effectively moving the excess traffic out of the overload period. Re-routing information would also be provided.
One of the main distinguishing characteristics of the TACT system compared with the Enhanced Tactical Flow Management System (ETFMS) was that it was a tool relying almost entirely on planned information i.e. flight plans, flight intentions. It did receive some real-time update messages but with insufficient frequency on which to base true re-assessments of the traffic situation. In the absence of consistent real-time updates, the system had to assume that flights would become airborne exactly in accordance with their planned EOBTs, that they would fly according to the four dimensional route calculated on the basis of the information given in the flight plan and the airspace and routing restrictions applicable at the time. It should be noted that the ICAO Field 15 format for providing route information is less than ideal where accurate profiles are required.
Since 7 February 2002, the Enhanced Tactical Flow Management System (ETFMS) has replaced the CFMU TACT system.
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In addition to the functionality of the former CFMU TACT system, ETFMS receives surveillance data i.e. radar derived data provided by the Air Navigation Service Providers (ANSPs), position report data provided by the aircraft operators and, meteorological data. ETFMS uses this data to update the existing data coming from flight plans and flow measures. The reception of this accurate real-time data allows ETFMS to re-calculate the current position and future trajectory of flights adding enormously to the accuracy of the data within ETFMS.
ETFMS provides the overall traffic situation for the CFMU area, both current and future, based upon flight plan data updated with current traffic position data, allowing a precise anticipation of the traffic demand. ETFMS brings benefits in the management of both routine traffic situations as well as unusual or 'exceptional' conditions.
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