Enhanced Tactical Flow Management System (ETFMS)

The Enhanced Tactical Flow Management System (ETFMS) is used to compare traffic demand with the available capacity of a certain air traffic control (ATC) sector. It is a key enabler of the air traffic flow and capacity management (ATFCM) services during tactical operations (on the day of the flight) and pre-tactical operations (from 1 to 6 days before the flight is airborne).

The ETFMS system has two main functions:

  • Calculation of traffic demand in every sector of the NM area of operations, using the flight plan information received from the aircraft operators (AOs) via the initial flight plan processing system (IFPS)
  • Computer-assisted slot allocation (CASA) – a more complex calculation, slot allocation and distribution of the resulting lists to all parties involved


ETFMS provides enhanced tactical data to all operational stakeholders, regardless of national boundaries, language, or equipment.

ETFMS facilitates improvements in flight management from the pre-planning stage to the arrival of the flight. It maximises the updating of flight-related data and thus improves the real picture of a given flight, thereby contributing to the Gate-to-Gate Concept.

Collection of flight and pre-flight data

The ETFMS receives information from most countries in the NM area of operations. It provides the Network Manager Operations Centre (NMOC) with an accurate update of the real-time flight situation prior to take-off and the arrival time calculated by the company once the aircraft is airborne.

This data includes inter alia the following: 

  • Estimated take-off time (ETOT)
  • Taxiing time (TT)
  • Departure route (SID)
  • Aircraft type and Registration
  • First System Activation (FSA) data, airborne updates, such as AFP (Airborne Flight Plan) or Aircraft Position Report (APR) data, US Federal Aviation Authority (FAA) departure planning information (FDI)
  • Correlated Position Reports (CPRs)

This information is collected from a variety of sources, including:

  • IFPS flight update messages;
  • aircraft Communications, Addressing and Reporting Systems (ACARS);
  • Departure Planning Information (DPI) from airports which have implemented collaborative decision-making (CDM) systems and procedures;
  • Departure Planning information (DPI) from Advanced ATC Tower airports, during the pre-flight phase;
  • participating companies concerning aircraft departing aerodromes outside the NM area of operations with destinations inside the area, and
  • the Federal Aviation Administration (USA).

Some data is derived from Aircraft Communications, Addressing and Reporting System (ACARS) information. These short messages provide the NMOC with an accurate arrival time, calculated by the company once the aircraft is airborne. These data are received before the flight enters the NM area of operations and allow the ETFMS to update the profile or trajectory of a flight. Such flights are usually exempted from flow measures, thus improving the sector load counts by optimising the slots of other (not yet airborne) flights.

Data collection system (DCS)

The ETFMS Data Collection System (DCS) is the technical infrastructure used to collect Correlated Position Reports (CPRs) and First System Activation (FSA) messages from the area control centres (ACCs) or from central decision-support systems and transmits them to the ETFMS central server in Brussels. At each site providing data, the Network Manager has installed Entry Nodes (ENs), which perform three main tasks. They:

  • receive surveillance data from processing systems such as ARTAS or from central flight data processing systems at frequencies ranging from 1 position every 3 minutes to several positions a minute,
  • match the flight data messages to surveillance data messages in order to add additional flight identification fields and, where relevant, convert geographical coordinates into standard latitude and longitude,
  • convert the surveillance data messages from a dedicated format into the ASTERIX cat 062 format.

For the majority of the ACCs, the Entry Nodes also receive FSA messages. The purpose of these messages is to supplement the CPR data, which often comprises just a call-sign, with other flight identification fields such as ADEP, ADES and, if available, EOBD and EOBT or IFPLID.

The FSA messages can also be collected through the NM B2B Web Services.

ETFMS currently receives CPRs from most countries in the NM area of operations.

Flight activation monitoring (FAM)

From the surveillance data it collects, the ETFMS knows which flights are airborne.  This makes it possible to identify flights – those which were scheduled to be airborne and those which are currently not airborne. The system’s flight activation monitoring (FAM) function enables it to

  • suspend those flights which are still not reported as airborne 30 minutes after their expected take-off time,
  • inform the aircraft operator and the departure tower of this development,
  • request an update to the flight plan.

This frees up air traffic flow management (ATFM) slots and thus reduces delays for flights which are not yet airborne.

FAM affects all flights which are departing from or arriving at aerodromes in the areas displayed on the image above.

Entry and sector occupancy counts

In its initial versions, ETFMS could only monitor the number of flights entering a sector once an hour (the so-called entry counts). ETFMS is now also able to monitor once a minute the number of flights which are actually present in a given sector – the sector occupancy counts. The use of occupancy counts improves the decision-making process, leading to the implementation of ground delay regulations or Short-Term ATFCM Measures (STAMs).

They are the main enablers of SESAR’s dynamic Demand Capacity Balancing (dDCB) concept. The objective of dDCB is to improve air traffic flow and capacity management (ATFCM) safety and capacity by reducing traffic complexity and streamlining air traffic controller workload.

Flight profile calculations

The implementation of real-time flight data updates in ETFMS improves the accuracy of flight profile calculations. The system also uses wind speed and wind direction in the calculation of the ATFM flight plan profiles. The MET data received contains forecasts for the next 36 hours in blocks of 6 hours. New data and updates are received every 6 hours.

Data distribution

When significant flight updates are made, ETFMS distributes its tactical ATFM flight data and trajectories to ANSPs, AOs and airports, including:

  • ETFMS flight data (EFD) messages, which provide ETFMS flight data to the ANSPs and AOs;
  • flight update messages (FUMs) which provide the airports with the estimated landing time (ELDT), and, in the case of collaborative decision-making (CDM) airports, flight status and an accurate estimated landing time for arriving flights.

These trajectories are used by the respective flow management positions (FMP) to assess how traffic demand varies over the operational day. Where traffic demand is higher than ATFM capacity, the FMP can implement a flow control measure to manage the rate of traffic inbound to a particular network flow or airport. This gives a common overview of the current and expected situation, allowing CDM.

Data Distribution Service (DDS)

This service is made possible by the accurate ETFMS representation of the current and predicted traffic situation via the broad coverage of the Correlated Position Report (CPRs). Combining this overview with the years of experience in CPR processing has considerably improved the accuracy of ETFMS flight profiles. The Network Manager shares this enhanced ETFMS data via its Data Distribution Service.

The Data Distribution Service is provided to:

  • ANSPs for flights entering the airspace of the ANSP via the Entry Nodes or via the NM B2B Web Services;
  • AOs for flights with flight plans submitted to the NMOC and with a registered ICAO airline designator or aircraft registration with NMOC as part of their service request, via the NM B2B Web Service or a VPN-capable Internet router following a software adjustment to the syntax and semantics described in the Flight Progress Messages document to properly process EFD messages;
  • airports for all flights to a given airport destination via AFTN or the NM B2B Web Service.

Data coverage conditions

The data distribution service applies to all general air traffic flights flying instrument flight rules (IFR GAT flights) which fly through the NM area of operations and for which NM receives flight data, regardless of the departure and/or arrival locations. Airborne updates are available mainly in the areas with CPR and FSA coverage.