Air traffic flow management

Published on Thursday 12 July 2018

Air traffic flow management (usually seen abbreviated as ATFM) is the regulation of air traffic in order to avoid exceeding airport or air traffic control capacity in handling traffic, and to ensure that available capacity is used efficiently.

Modernization of Air traffic flow management

Dynamic – Managing Traffic Complexity

A consolidated concept Based on CDM manages traffic complexity and improves flight efficiency. Ensuring time-based operations to serve global performance : DSNA’s expertise is at the heart of the SESAR operational concept.

When traffic is both high and complex, classic ATFCM/ATC procedures are not efficient enough. As Europe’s leading provider of air navigation services with 2.9 million ᴀights controlled, DSNA has developed a new concept in its day to day operations to manage traffic complexity and to streamline controller’s workload : the Dynamic-ATFCM.

This process is based on the following pillars :

  • Flight Management Position (FMP)
  • Extended ATC Planner
  • Advanced ATFCM/ATC procedures
  • Dynamic-Airspace Management (ASM), a model of advanced civil-military integration.

By dynamically organizing airspace to meet trafficdistribution, then by tackling excessive workload only and smoothing out trafficfor ATC, this dynamic process results in increased capaci-ty while maintaining a high level of safety and directly improving fight efficiency.


La DSNA optimise la gestion des arrivées grâce à de nouveaux concepts opérationnels.

Respecter l’heure cible d’arrivée (TTA) des vols de démonstration effectués en 2013 ont montré que FAIR STREAM (FABEC ANSPs et AIRlines in SESAR TRIALS for ENHANCED Arrival Management) ouvre la voie à une meilleure prédictibilité conduisant à une gestion plus lisse des vols. Les pilotes, avec les équipements embarqués existants savent respecter une heure-cible d’arrivée.

Tous les acteurs étant informés de la TTA, dans un espace aérien saturé, l’efficacité du vol sur le réseau de routes sera améliorée.

Vidéo - Fair Stream

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The objective of the FAIR STREAM project was to pave the way for the use of target time of arrival ( (TTA) instead of - or complementary to - calculated take-off time (CTOT)

XMAN Concept

XMAN Concept

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The XMAN Heathrow trials: the delay sharing strategy between London Terminal (LATC), London ACC (LACC) and Reims UAC (En-route)

XMAN : the operational concept

Traditionally, NATS, the UK’s air traffic service provider, can only influence an aircraft’s approach to Heathrow once it enters UK airspace, which is sometimes only 80 miles from the airport. This limits the opportunity to manage the inbound flow of traffic with the neighbouring Air Traffic Services units and can result in extra time spent in the holding stacks. This procedure burns more fuel, costs the airlines more and produces more CO2 emissions and NATS’ aim is always to minimise the amount of time aircraft have to spend in them.

The XMAN concept (“Cross-Border Arrival Management”)

Developed together by the FABEC and the UK-Ireland FAB introduces the ability for controllers to manager delays in the tactical phase of flight well before the top of descent. When the destination airport is congested, air traffic controllers can ask for pilots to slow down in the more efficient en-route phase of flight in order to minimise delays upon arrival. This service is only possible thanks to the excellent cooperation between units and across operational borders. The procedures result in some added workload for controllers, but this is entirely manageable and does not impact on their performance or the service offered to other flights.

Predictability reinforces safety

Providing customers with tangible pre tactical and tactical solutions is a necessity to respond to cost and fuel efficiency demands. That is the reason why DSNA has developed a high degree of expertise in traffic flow and capacity analysis.

Flight plan adherence becomes a safety need

Pre tactical measures are implemented to prevent ATC sectors from receiving more traffic than the controllers can safely handle. All this work is based on flight plan profiles, as filed by the airlines and accepted by Eurocontrol’s Network Manager in Brussels. Any breach into this fine-tuned process may result in a capacity issue, leading to over-deliveries (defined as the delivery of 10% more traffic than the declared capacity) thus incidentally to a safety issue.

Ops rooms GB
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The analysis of such events show that flights were not flying at the filed cruising level, flying a different route than the one planned or departing outside the estimated time slot allowed by the system.
When flying a different profile than the one planned, crew may enter a control sector wherein they were not expected, causing potential over-deliveries and disruption in ATC anticipation.

Pre tactical measures are also applied to ensure timely and efficient service

Ensuring the best traffic flow predictability also enhances the effectiveness of the network demand/capacity optimisation throughout the European airspace.
When flying a different profile than the one foreseen, crew will not fly in awaiting sectors, thus wasting capacity for the others.

The main objective is to reach global awareness of the network constraints

Therefore, in the best interest of all operational actors, best practices need to be followed all year round. What do they consist of ?

  • Unless there is an unquestionable operational issue or for any safety reasons, crew should comply with their filed flight plan.
  • Before accepting any changes to the flight plan (flight levels or route), ATCOs should assess the consequences with their Flow Management Units and promote mitigating solutions when available.
  • ATCOs will not suggest changes that may impact the traffic flow counts, especially in regulated sectors.


A “Zero rate”

A “Zero rate” is one of the possible ATFM measure to be used when unpredicted adverse weather causing major disruptions arise. It allows approach & en route units to handle all inflight planes with safety in mind before considering adjusted flow regulations to take over additional traffic.

Airborne flights are never affected by a zero rate and it does not mean that the airport is closed.

It is a temporary, precautionary and protective measure to ensure safety in particularly uncomfortable operational situations for either crews or ATC.
Indeed, departures and arrivals rely on operating minima to be fulfilled. If they cannot be reached, crews have no other choice than cancelling take-off, going around if on final approach, holding or diverting if the disruption of service cannot be precisely estimated. Crews can always take the decision to fly the procedure in use all the way to the MAPt (Missed Approach Point) to assess the flying conditions in real time.

When applied on arrivals, the “zero rate” means that the airport does not accept traffic that has not yet left its departure airfield. However it only captures flights originating from ATFCM and adjacent areas. A different process would have to be followed for exempted flights.
The zero rate can be implemented for an airport, either for departing or/and arriving traffic.

This specific ATFCM measure does not prevent from the dissemination of NOTAM towards the entire aeronautical community as a means of information.

“Zero rate & ATFM process”
For the non-availability of airports of more than one hour, FLS (Flight Suspension) messages are sent to AOs, thus suspending all non-airborne flights originating from ATFCM or adjacent areas to the concerned airport. AOs must send a FCM (Flight Confirmation Message) if the flight still intends to operate. SAM (Slot allocation Message) or SRM (Slot revision Message) would be received to allow them to depart and eventually provide the concerned airport with a sequenced arrival flow as soon as the time period covered by the “zero rate” is over. If AOs intend to operate to an alternate destination, they must cancel their FPL and file a new one.

DSNA will ensure that all ATFM measures are coordinated with the concerned airport operators, in order to ensure efficiency in airport planning and usage. (CF European Commission Implementing Rule 255/2010).

The Flight Plan Conformance Tool

Selecting candidates to avoid over deliveries

Reims Area Control Centre (ACC) has developed a tool to identify flights that are not complying with their filed profiles. An extensive operational evaluation to assess the introduction of this new tool and the associated working methods has started in March 2015.


2012, 2013 and 2014 Summers have shown an important increase of traffic during peak hours. Traffic distribution and concentration have a significant impact on air traffic management, emphasizing the need for accurate traffic counts. Between 2 and 3 hours in advance, the operational room strategy relies on these traffic counts and as such, they need to be as close as possible to the reality. Reasonable consistency between filed and flown flight levels is therefore a key element in not wasting any airspace capacity for the aircraft operators.

A new flow management support tool

The “Flight Plan Conformance Tool” will help Reims ACC flow management unit to identify, at a glance, the flights that may unexpectedly enter each of their control sectors and that are therefore not counted in the initial traffic load. The controller using this tool will know how many flights are concerned and the sectors they affect. It is designed to help him in its choice for the best candidate and the least penalizing flow management measure to apply.

The Flight Plan Conformance Tool is an additional support tool for controllers to :

  • deliver tactical traffic flow adjustments,
  • ensure that capacity isn’t wasted,
  • provide aircraft operators with the full airspace potential.

This new tool has a detection window from 1 to 10 hours but is usually used from 15 minutes to 3 hours ahead. If a hotspot is declared, the flight list of the relevant sector will show the candidates for short term air traffic flow management measures (STAM) and the controllers will give instructions to comply with the filed flight profile in order to avoid the sector and prevent from an over delivery.
Pro-active profile monitoring is facilitated providing that their identification can be achieved at least 15 minutes prior to their entry into the sector. It thus allows the necessary anticipation for flight plan adherence actions ensuring to be timely coordinated.

Full flight plan adherence cannot and will not be achieved. Indeed, filed flight levels cannot always be assigned as they rely on real time conditions and availability, disruptions or unusual situations may arise leading to the impossibility of systematically complying with what has been filed.

The main objective is not to reduce the flexibility of the airspace for our customers but only to achieve better predictability when the demand is at its highest and the safety is concerned.

DSNA Collaborative Advanced Planning

CAP - Improving on time performance while optimizing use of airspace

The Collaborative Advanced Planning consists in agreed pre-tactical level capping measures applied to a selection of flights. Such measures are taken in complete collaboration with the involved airlines. The results are a better predictability of the traffic demand and a lesser use of control sector regulations. The process is essential to correctly spread the tactical demand between all the available control sector layers.
For the first time this year, the CAP on the traffic flow from Southern Europe and the Mediterranean to the UK (i.e. BRY-CLM) will involve the business aviation, which represents a significant number of flights during the winter season.

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Air Traffic Flow and Capacity Management (ATFCM) scenarios

ATFCM scenarios are put in place to find short term solutions to traffic congestion during the busiest times of the year (i.e. Ski season, holidays, sports events). They have also proven precious to airlines as contingency solutions in case of limited airspace availability.
Scenarios are mostly level capping scenarios meant to spread the traffic throughout the different control sector layers of a busy airspace and avoid the implementation of a regulation. In terms of service rendered, it provides the airline community with a trade-off between on-time operations and flight efficiency during peak-hours.

However, for the most important bottlenecks, compulsory scenarios have to be implemented because the demand is way too high and safety is at risk as it may lead to an important overload.

R control sector

R control sector

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In summer 2016, for the busy R control sector block in Reims ACC, with the implementation of compulsory level-capping scenarios applied to specific departure airfields and destinations, some airlines have seen their ATC capacity delays reduced by 60% compared to summer 2015

The definition of scenarios to apply are decided in axis meetings involving all concerned DSNA Flight Management Position (FMP) units, adjacent ANSP, Aircraft Operators and the Network Manager

The axis meetings consist in face to face meetings 3 months prior the beginning of the season to discuss and agree on the most efficient ATFCM solutions to put in place during the busiest times of the season (i.e. scenarios, RAD restrictions, city-Pairs, etc.).

For the rest of the process:

  • pre-tactical analysis to update the status of the traffic demand and the route network as far as military activities are concerned. The objective is to refine the ATFCM measures agreed upon in case of a detected potential overload on a control sector.
  • tactical monitoring and problem solving by the DSNA FMP in close coordination with NM to suggest options in case of significant disruptions

DSNA iterative and collaborative summer ATFCM plans

To manage the busiest traffic flow in a coherent, comprehensive and collaborative way with its customers and partners, DSNA has launched the MAC project. The MAC project is a set of short term Air Traffic Flow and Capacity Management (ATFCM) solutions to best answer the summer season’s traffic hotspots while pushing back the need for a systematic traffic regulation implementation and its induced delays.

MAC refers to ATFCM Collaborative Measures
We have prepared for you a slide pack detailing all the MAC 2018 ATFCM solutions

Download your OCC briefing slide pack below

The project is iterative and will ensure that the lessons learnt from the previous plans are taken into account.

Download the MAC 2018 information leaflet below.


Flight safety at risk with unusual/unexpected flight planning

A flight plan is a contract sealed between ATC and airlines to share the same vision of a flight trajectory. When this contract becomes abnormal and non-standard as regards usual routing for the same destination, Air Traffic Management (ATM) procedures are needlessly disrupted and most particularly as aircrews are rarely aware of such unusual filed flight profile and rarely fly them. Best practices need to be agreed upon to eradicate unusual/unexpected flight planning particularly with the busiest summer times ahead.

« Best-off » from unusual/unexpected flight planning

When real reported events explain it all.

Note that more efficient and direct routes could have been filed with no particular machine unreadable route restrictions.

Extra-mileage routes

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Flight from Geneva to Roma. The blue trajectory is the filed route, the yellow the usually filed one. The difference is 280 extra nautical miles!

For the following examples, the blue line is the filed flight plan or flight level filed, the white line is the flown route or level.

Abnormally low Requested Flight Level

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Critical turns

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Yo-Yo flights

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Taking actions against unexpected flight planning

As these flight planning are not consistent with real-time ATM by disrupting the usual traffic flows, aircrews rarely if ever fly them. It is unsafe for ATC to integrate such profiles in busy airspaces. The flight plans will be tactically updated to ensure system to system coordination but inducing additional workload and downgraded predictability. Capacity is therefore wasted. To avoid too many reactive solutions (e.g., RAD restriction implementation that tends to make flight planning even more difficult), we need to take actions together.

DSNA has prepared educational material to raise airlines’ operations and aircrews’ awareness on the effects of such flight planning onto the global traffic management. We need the help of the airline community and flight plan service providers to eradicate aberrant flight planning.

DSNA Flight Management units are here to help process the flight planning mistakes in the post ops phase. However, airlines and aircrews should take back control of the flight plans they file and fly. The flight plan should reflect the flight path the OCC (Operating Control Centre) and the aircrews wish to fly.

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The Marseille ACC Route Availability Document's (RAD) issues

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