ENR 1.9  Air Traffic Flow Management (ATFM) and airspace management

1.9.1   Airspace Management (ASM)

1. Objective

Airspace Management is any activity provided for the purpose of achieving the most efficient use of airspace based on actual needs and, where possible, avoiding permanent airspace segregation. Airspace management is based on ECAC principles, namely the concept of Flexible Use of Airspace (Regulations (EC) 551/2004 and (EC) 2150/2005; EUROCONTROL Specification for the application of the Flexible Use of Airspace; EUROCONTROL ASM Handbook - Airspace Management Handbook for the Application of the Concept of the Flexible Use of Airspace).

2. General Organization and Responsibilities

ASM has 3 levels:

AMC Portugal address:
Centro de Controlo de Tráfego Aéreo de Lisboa
Rua C, Edifício 118, Aeroporto de Lisboa
1700-007 Lisboa, Portugal

Tel: +351 218 553 322

Fax: +351 218 406 193


Email: amc@nav.pt

1.9.2   Air Traffic Flow and Capacity Management (ATFCM)

1. Objectives

ATFCM is a service that is enhancing ATFM with the objective of managing the balance of demand and capacity by optimising the use of available resources and coordinating adequate responses, in order to enhance the quality of service and the performance of the ATM system.

2. ATFCM Phases

ATFCM consists of 4 phases:

  1. Strategic Flow Management takes place seven days or more prior to the day of operation and includes research, planing and coordination activities. It is a co-operative approach of EUROCONTROL involving several units and also all the partners involved in ATM (ANSPs, airports, airspace users, military). The output of this phase is the Network Operations Plan (NOP), that responds to the requirement developed in the context of the Dynamic Management of European Airspace Network (DMEAN) Framework Programme and in the EU Network Management Function Implementing Rule as a single document that incorporates the existing information on traffic demand and capacity plans for each season, identifying bottlenecks and presenting the ATFCM and ASM measures foreseen to counterbalance them.
  2. Pre-Tactical Flow Management is applied during the six days prior to the day of operation and consists of planning and coordination activities. This phase analyses and decides on the best way to manage the available capacity resources and the need of the implementation of a wide range of appropriate ATFCM measures. The output is the ATFCM Daily Plan (ADP) published via ATFCM Notification Message (ANM) / Network News and via the NOP portal.
  3. Tactical Flow Management is applied on the day of the operation. This phase updates the daily plan according to the actual traffic, capacity and monitoring values.
  4. Post Operational Analysis is applied following the day of operation. This phase analyses the day of operation, and feeds back into the previous 3 phases

3. A Centralised Air Traffic Flow Management (ATFM) service is established within the ICAO (EUR) Region to optimise the use of air traffic system capacity. The Eurocontrol Central Flow Management Unit (CFMU) in Brussels provides this service in co-ordination with Flow Management Positions (FMPs) established at Lisboa ACC and Santa Maria ACC.


NAV, Portugal -E.P.E. - Lisboa FMP
Centro de Controlo de Tráfego Aéreo
Rua C, Edifício 118
1700 - 007 Lisboa


NAV, Portugal - E.P.E. - Santa Maria FMP
Centro de Controlo de Tráfego Aéreo
Apartado 47
9580 - 909 Vila do Porto





Fax:+351 218553658





Tel:+351.296.820438 or







1.9.3   CFMU Procedures and Information

Specific CFMU procedures and information can be found in the CFMU Handbook published by the CFMU and available from:


Eurocontrol Library
Rue de la Fusée 96, B
1130 Brussels



or from the CFMU website at: http://www.cfmu.eurocontrol.int under User CFMU Publications.

Basic CFMU Handbook sections include:

Information regarding ATFM measures will be available at the ATS Reporting Offices (AROs) of airports concerned and also through AFTN or SITA upon request to the following addresses:



IFPS addresses for all flights and associated messages are:

IFPU - 1Haren, BelgiumIFPU - 2Bretigny, France

NOTE: All flight plans and associated messages (DLA and CHG) must be addressed TO BOTH IFPS UNITS

The ATFM Notification Message (ANM) has become the only official medium for notification, in consolidated form, of all planned or in force ATFM measures in the ECAC Area.

The ANM provides an overall description of all regulations planned for the CFMU area.

Additional information concerning special situations will also be available trough ATFM Information Messages () and ANM Flash Messages (ANM FLASH).

1.9.4   ATFM Measures

Amongst other things, the Slot Allocation Procedure and the offering of recommendations for alternate routes are part of ATFM measures. For details of the Slot Allocation Procedure see paragraph 5, for possible flights on off-load routes and filling of alternate flight plans see paragraph 6 of the ATFM Users Manual.

In this context, the following measures, either individually or combined, may be applied by the CFMU:

  1. early allocation of Slots for departures to specific destination areas or for departures to specific aerodromes in order to prevent an overload by allocating a Slot,
  2. proposals for off-load or alternate routes,
  3. allocation of Slots for selective ATFM Measures for arrivals,
  4. suspension of individual flights or certain preconditions.

When no other option is available, a regulation will be applied by FMD (Flight Management Division) and delays issued in the form of a Calculated Take Off Time (CTOT). This is facilitated by Computer Assisted Slot Allocation (CASA) a FMD system.

The CTOT is defined as a time and a tolerance (Slot Window) during which the aircraft must Take-Off. The Value of the Slot Window is from -5 to +10 minutes around the CTOT. The Slot Tolerance is primarily intended for use by ATC to allow for aerodrome congestion problems, and therefore aircraft operators should make every effort to be at the holding point at the commencement of the Slot Window.

For flights subject to a regulation, the CASA system will send a Slot Allocation Message (SAM) containing a CTOT at EOBT (Estimated Off-Block Time) 2 hours in advance. This will be sent to the ATC Units involved as well as the Aircraft Operator via AFTN or SITA.

Revisions to, or cancellations of, the last issue CTOT may be initiated by FMD, the Aircraft Operator () or a local FMP/ATC Unit on behalf of the .

All CTOT revisions or cancellations are to be made using the ATFM message exchange procedures described in the CFMU Handbook.

The allocation of a departure Slot and/or a change of a SLOT, as well as a possible suspension of a flight, are made by making use of a standardised message format. The message formats as well as their operational application can be taken from the CFMU Handbook, part ATFM Users Manual.

Full details of the Slot Allocation Process are published in the ATFM Users Manual.

1.9.5   Flight Planning

The ATFM rules for Flight Planning, as defined in ICAO Doc 7030, are:

  1. For Flights likely to be subject to ATFM measures, Aircraft Operators shall submit Flight Plans to IFPS at least 3 hours before the Estimated Off-Block Time (EOBT).
  2. AOs filling flight plans for flights within the FMD ATFM area or from within the ATFM adjacent area and entering the ATFM area, shall assume their flight is subject to ATFM measures and subject to the requirements, to submit a flight plan at least 3 hours before EOBT.
  3. AOs should be aware that late filling of a flight plan may lead to a big delay.
  4. It is very important that the EOBT is as accurate as possible. It is an European requirement that all controlled flights departing, arriving or over-flying Europe subject to a change in an EOBT of more than + or - 15 minutes shall notify the change to the CFMU (see sub-section 1.9.7)

It is the best interest of AOs to initiate prompt revisions or cancellations, thus permitting the system to maximise use of available capacity and minimise delay. The later the revision is made the grater the probability of a delay.

The correct application of the STS/ATFMX procedure will ensure that approved flights are not unnecessarily delayed. (see paragraph 1.9.10 for details of the ATFM exemption procedures).

1.9.6   Slot Monitoring

ATC is responsible for Slot Monitoring at Aerodromes of departure. The exact procedure to be observed depends on the organization of the Air Traffic Services at the respective aerodrome. However, the following requirements must be met:

  1. The CTOT and/or Slot Time available to ATC shall be communicated to the Pilot in-command at last once, preferably directly after start-up clearance as been requested,
  2. The necessary information about valid restrictions and allocated Slots shall be made available to the ATC Units responsible for departure Slot Monitoring,
  3. ATC shall monitor flight compliance with the departure Slots issued by the FMD taking into account the Slot Window of -5 to +10 minutes.

In accordance with the provision of the Regional Supplementary Procedures, Europe (ICAO Doc 7030), flights which do not adhere to their Slot shall be denied Start-up clearance. However, ATC shall make every effort to enable departing flights to comply with the Slot. ATC shall liase with the relevant FMP to co-ordinate extensions to CTOTs.

The current CTOT expires after a maximum of 30 minutes.

With the progressive introduction of the CFMU Enhanced Tactical Flight Management System (ETFMS) and Flight Activation Monitoring (FAM), flights that are not notified as being airborne within 30 minutes of the notified ETOT or CTOT will receive a Flight Suspension (FLS) message.

Aircraft Operators are responsible for informing themselves of the following regulations and adhering to:

  1. General ATFM procedures including Flight Plan filling and message exchange requirements,
  2. Strategic ATFM measures (including Route Availability Document (RAD )),
  3. Current ATFM measures (including specific measures applicable on the day of operation, as promulgated by ANM or Flight Suspension (FLS) message),
  4. Departure Slots (CTOTs) issued by the FMD and procedures related to changes to CTOTs,
  5. The CFMU requirement for the modification or delay of EOBT,
  6. The sole responsibility to obtain a new CTOT if there is no RTF contact with the TWR at CTOT,
  7. The correct procedure to followed to obtain approval for the use STS/ATFMX.

1.9.7   Modification of Estimated Off-Block Time (EOBT)

It is a requirement for both ATC and ATFM that the EOBT of a flight shall be an accurate one. This applies to all flights, whether subject to ATFM or not. Any change to the EOBT of more than 15 minutes (+ or -) for any IFR flight within the CFMU Initial Flight Planning Zone (IFPZ) (see IFPS Users Manual for details) shall be communicated to IFPS.

An Aircraft Operator should not modify the EOBT to a later time simply as a result of an ATFM delay. When an submits an amendment message (DLA or CHG) to IFPS, they must always give the earliest EOBT they may comply with, and it should reflect, no more than, the time the wants to be off-blocks. The EOBT should always be changed if the original one cannot be met by the for reasons other than ATFM delay.

Flights that has not received an ATFM CTOT (SAM- Slot Allocation Message)

  1. To amend the EOBT to a later time, a DLA or CHG message shall be sent to IFPS,
  2. To amend the EOBT to an earlier time, a CNL message must be sent to IFPS followed five minutes later by a new Flight Plan with the new EOBT indicated.

Flights that as received an ATFM CTOT (SAM - Slot Allocation Message)

  1. If the EOBT established by the has changed or is no longer realistic for reasons other than ATFM then the following procedure shall be used:
    1. If a flight has a CTOT that cannot be met, then the shall send a delay message to IFPS with the new EOBT of the Flight. This may trigger a revised CTOT,
    2. If a flight has a CTOT with some delay and the is aware that the original EOBT cannot be met but the existing CTOT is acceptable, then a message shall be sent to IFPS with the new EOBT of the Flight. However, in order not to trigger a new CTOT, the following formula must be used:

      Take the current CTOT minus the taxi time, minus 10 minutes. The new EOBT must be not after this time (e.g. - original EOBT 09:00, CTOT 10:00, but the flight cannot go off-block until 09:25. Taxi time is ay 15 minutes. 10:00 minus 15, minus 10 = 09:35. if it is, then this action will not trigger a revised CTOT).

      Be aware that CTOT of the flight will never be earlier than the new EOBT plus the Taxi time.
  2. If a flight has had a CTOT (SAM - Slot Allocation Message) and now receives a Slot Cancellation Message (SLC), but the original EOBT can no longer be met, then the shall communicate the new EOBT by use of a Delay Message (DLA).

It is not possible to amend the EOBT (via DLA or CHG) to an earlier time than the EOBT given in the flight plan. However, if a flight is ready to go Off-Blocks earlier (maximum 15 minutes before) than the current EOBT, the may ask the local ATC Unit (TWR), or the FMP, to send a Ready Message (REA). This request may be refused if it is considered not justified.

1.9.8   Modification of Calculated Take-Off Time (CTOT)

A Slot Improvement Proposal (SIP) Message will be sent to the proposing a new take-off time, whenever it is possible to improve the existing CTOT by a significant amount. Such a message will be originated at the CFMU TACT/CASA System and transmitted to the concerned.

The concerned must respond to the message mentioned above, using a Slot Proposal Acceptance Message (SPA), in case the flight is able to comply with the proposed new CTOT, or using a Slot Improvement Proposal Rejection Message (SRJ) in case the flight is not able to meet the proposed new CTOT.

If the proposed new CTOT is acceptable, CFMU will confirm the accepted Slot with a Slot Revision Message (SRM).

The Slot Improvement Proposal (SIP) expires if no response is received from the by the (respond by) time included in the message. In this case the flight will keep the original CTOT.

When a flight in receipt of a Slot Allocation Message (SAM) is no longer subject to a regulation, a Slot Cancellation Message (SLC) will be sent to the and to the applicable ATS Units.

A Slot Cancellation Message does not guarantee that the flight will not be subject to further regulations. If following the receipt of a SLC a new regulation affecting the flight is imposed the will receive a new Slot Allocation Message (SAM).

A Re-routing Proposal Message (RRP) may be sent to the to propose a different CTOT or to avoid the need for a Slot on a new route.

A Re-routing Proposal Message may be sent to the before the issuance of a Slot Allocation Message (SAM). This happens when a overload was detected some hours in advance.

The accepting the RRP shall modify his flight plan either with a CHG or a CNL and refill.

1.9.9   Flight Activation Monitoring

Flight Activation Monitoring (FAM) is a tool of the Enhanced Tactical Flow Management System (ETFMS) which enables the CFMU to receive, from the areas where this tool is implemented, live data on flights. This data is provided by the ATC systems and is derived from ATC radar information and flight plan messages. FAM already covers Portugal.

The Flight Activation Monitoring (FAM):

  1. Monitors flights which should have departed;
  2. Takes the necessary action on these flights (via internal messages to CFMU) to up-date the Take-Off time in order to improve the forecast of traffic demand;
  3. Suspends flights after the established time parameter (30 minutes after CTOT or ETO), unless a message is received to confirm that the flight is airborne or delayed;
  4. Informs s and ATC at the departure aerodrome of any flight suspension enabling these partners to react accordingly.

ETFMS expects flights to be airborne, base on the filed EOBT or the ATM Slot departure time issued in the SAM. Those flights that are not notified as being airborne through ATC up-dated messages within 30 minutes of the FAM or CTOT time will receive a Flight Suspension Message (FLS) from ETFMS and will remain suspended until signal action is taken. The comment “Not reported as airborne” will be added to the text.

Any changes of EOBT for both regulated and non-regulated flights must be notified only by means of a DLA/CHG message to IFPS.

Flight Plan Originators are reminded that all changes to the EOBT of more than 15 minutes must be notified to IFPS to prevent the risk of being suspended, and to give the CFMU the possibility of optimising the airspace capacity.

ATC should not let a flight, that has received a FLS Start-up/depart before a De-suspension Message () or Slot Revision Message (SRM) is received.

1.9.10   ATFM Exemptions

Due to their special nature certain types of flights may be excluded from ATFM measures.

The following principles apply:

  1. The insertion of a STS/... indicator in Field 18 of a Flight Plan will identify that a flight may require special handling. This indicator is for use by all parties that will handle the flight;
  2. The current list of STS/ indicators recognised for ATFM purposes comprises STS/ALTRV - STS/FFR - STS/FLTCK -STS/HAZMAT- STS/HEAD - STS/HOSP - STS/ - STS/MARSA - STS/MEDEVAC - STS/NONRVSM - STS/SAR - STS/STATE;
  3. Additionally, STS/ATFMX may be used if that particular flight has received specific approval from the Office established by the National Administration for processing such request;

It should be noted that:

  1. Only STS/HEAD, STS/SAR, STS/FFR, STS/MEDEVAC and STS/AT FMX qualify for automatic exemption from ATFM measures;
  2. The indicator STS/ATFMX is only used for ATFM purposes and is additional to any other special handling notification that may be required to be shown for ATC purposes as STS/... in Field 18 of flight plan.

Further information on the use of STS/indicators for ATFM purposes may be found in the ATFM Users Manual published by the CFMU and available in the CFMU web site.

The following Rules of Application shall be applicable to all flights seeking to gain exemption from ATFM measures within the area of responsibility of the CFMU. It is intended to ensure that flights, by the nature of their mission, cannot under any circumstances be delayed due to ATFM. It is based on the (ICAO EUR Doc 003, ATFM-HB/2) and existing material in the CFMU Handbook.

General Rule

Any flight meeting the criteria established to warrant exemption status may, provided the necessary approval procedure has been followed and the flight duly authorized by the Office established by the State for processing such requests, use STS/ATFMX for that flight and that flight only. Each flight shall require specific approval to use STS/ATFMX.

Guidelines for determining the need for use of STS/ATFMX for an individual flight:

If the answers to any of the above questions are YES then the flight may apply for approval to use STS/ATFMX through the procedure specified on the next paragraph.

Procedure for requesting authorization for the use of STS/ATFMX

The operator of a flight seeking to insert the indicator STS/ATFMX in the Field 18 of a flight plan for a flight departing from an aerodrome within Portugal shall:

1.9.11   ATFM Message Exchange

The Slot Allocation, Slot Modification and associated messages, relies to a large extend on a exchange of ATFM Messages between the Aircraft Operators, The CFMU and the applicable ATS Units. Therefore, ATFM Messages must be conform to the proposed Eurocontrol standard messages format in use within the ECAC States, the ATS DATA EXCHANGE PRESENTATION (ADEXP).

All the messages its Definition, Procedure and Contents are available in the ATFM Users Manual, part of the CFMU Handbook and may be available in the CFMU Website:

http://www.cfmu.eurocontrol.int - under User CFMU Publications