ATFM Slot Adherence


Contact organisation EUROCONTROL: The European organisation for the safety of air navigation
Contact organisation unit Directorate European Civil-Military Aviation - Performance Review Unit (DECMA/PRU)
Contact name Performance Review Unit - EUROCONTROL
Contact mail address 96 Rue de la Fusée
1130 Brussels
Contact e-mail address

Metadata update

Metadata last certified not applicable
Metadata last update 01 November 2016

Statistical presentation

Data description

ATFM departure slots are allocated centrally by the European Network Manager upon the request of the local Flow Management Position (FMP), when an imbalance between demand and capacity is foreseen at airports and/or en-route. The purpose of such regulation is to hold aircraft on the ground.

An ATFM slot tolerance window is available to ATC to sequence departures. The standard slot tolerance window is [-5 minutes, +10 minutes]. ATC at the departure airport has a joint responsibility with aircraft operators to ensure that flights departure within the allocated ATFM slot tolerance window in order to optimise traffic flow. ATFM departure slot adherence, simply named ATFM slot adherence hereafter, measures the share of take-offs inside the slot tolerance window of [-5 minutes, +10 minutes].

ATFM slot adherence monitoring is a pre-requisite to fine tune traffic predictions at the departure, en-route airspace and at the destination airports. The higher the number of regulated departing aircraft inside the assigned ATFM standard window, the more accurate the predicted traffic and associated down-stream ATFM measures.

ATFM slot adherence monitoring is required by the Regulation (EU) No 255 / 2010. Under Article 11 of this regulation, the ATS units are required to provide the information regarding non-compliance to slot adherence for these airports where non-adherence equals or exceeds 20% of the regulated departures, as well as their action plans to mitigate such a non-compliance.

In application to Regulation (EU) No 2552010, the Network Manager monitors ATFM slot adherence on a monthly basis.

The Performance Regulation (390 / 2013), Annex I Section 2 para 3.2(a) also requires ATFM slot adherence to be monitored at local level, i.e. at national level with a breakdown at airport level.

Classification system

ATFM slot adherence is classified per Member State, with a breakdown for each airport subject to EU IR390.

Sector coverage

The measures pertain to the Air Transport and Air Traffic Management Sector of the economy.

Statistical concepts and definitions

ATFM slot adherence is defined as the percentage of departures inside an ATFM slot tolerance window of [-5 minutes, +10 minutes].

Statistical unit

The statistical unit is the airport. Airport level data is also aggregated to States.

Statistical population

The statistical population is the set of ‘the 2nd reference period (RP2) airports’ subject [EU IR390 / 2013]]law, within the Single European Sky Area.

Reference area

The reference area is the Single European Sky Area of RP2 (2015-2019).

Time coverage

The Network manager has monitored slot adherence to ATFM since 2011, but in the scope of the Performance Scheme, 2015 is the first year for which data is presented.

Base period

Not applicable.

Unit of Measure

The ATC pre-departure delay is measured in minutes per outbound IFR flight [min/departure].

Reference period

As fixed by the Performance Regulation (390 / 2013), the second reference period (RP2) for the performance scheme shall cover the calendar years 2015 to 2019 inclusive.

Institutional Mandate

Legal acts and agreements are established in the Commission Implementing Regulation (EU) No 390 / 2013.


The information is disseminated in accordance with Article 21 of Commission Implementing Regulation (EU) No 390 / 2013.

Release policy

Release calendar

ATFM slot adherence is released monthly with yearly aggregates.

Release calendar access

Not applicable.

User access

Information is disseminated to the general public via the SES Data Portal.

Frequency of dissemination

Data is published monthly with the annual performance aggregate being available in January of the following year.

Dissemination format

Information is disseminated to the general public via the SES Data Portal.

Accessibility of documentation

Documentation on methodology

As per the pertaining regulations (see Institutional Mandate).
For technical questions not addressed in Statistical processing please contact:
Additional definitions of the terms used in the frame of the this KPI are available in the Metadata page.

Quality documentation

There is no specific documentation on procedures applied for quality management and quality assessment.

Quality Management

As per Performance Regulation (390 / 2013), Article 21 (3),

The data providers shall take the necessary measures to ensure the quality, validation and timely transmission of the data, including providing evidence of their quality checks and validation processes, explanations in response to specific requests from the Commission regarding the quality of the data and, where necessary, action plans to improve data quality. The data shall be provided free of charge, in electronic form where applicable, using the format specified by the Commission.

Quality assurance

Data validation is performed by the Network manager in the the Regulation (EU) No 255 / 2010.

Quality assessment

Quality assessment is under the responsibility of the Network manager in the context of the Regulation (EU) No 255 / 2010.


The data is collected for all the RP2-airports.


The information is published for performance monitoring purposes in accordance with Article 3 of the Performance Regulation (EU) No 390 / 2013.

Accuracy and reliability

Overall accuracy

The information is published for performance monitoring purposes in accordance with Article 3 of the Performance Regulation (EU) No 390 / 2013.

Sampling error

There is no sampling and therefore no sampling error.

Timeliness and punctuality


The information is published each month by the Network Manager in their “NM Monthly Adherence to ATFCM Slots” bulletin.


The internal databases are updated daily. The statistical processing is performed once per month.


Comparability — geographical

The data is collected centrally by the Network Manager, as required by the Regulation (EU) No 255 / 2010. In the scope of the Performance Regulation (390 / 2013), the data is transmitted to the EUROCONTROL Performance Review Unit and computed consistently for all the EU IR390 airports.

Comparability over time

Comparisons over time are valid.


Coherence — cross domain

Not available.

Coherence — internal

Data is fully coherent from an internal perspective.

Cost and burden

Not available.

Data revision

No data revision foreseen.

Statistical processing

Source data

The input variables used for the calculation are detailed in the Statistical concepts and definitions section.

Frequency of data collection

The data is collected and transmitted for statistical processing on a monthly basis.

Data collection

The data is collected by the Network Manager for the purpose of Regulation (EU) No 255 / 2010 and transmitted to the EUROCONTROL Performance Review Unit for the implementation of the Performance Regulation (390 / 2013).

Data validation

The data is validation as described in the Quality Management section.

Data compilation

The departure time of a regulated flight is inside the slot tolerance window when its Actual Take-off time (ATOT) is in a window starting 5 minutes before and ending 10 minutes after its Calculated Take-Off time (CTOT), i.e.

$$CTOT – 5 min <= ATOT <= CTOT + 10 min $$

It should be acknowledged that the exceptional extension of the standard ATFM slot tolerance window [-5 minutes, +10 minutes], as described in the ATFCM User Manual under 4.6.4 “Adverse Operating Conditions at Aerodromes”, is not taken into account in the calculation of ATFM slot adherence. These exceptions represent in most cases less than 2% of regulated flights.

The adherence to ATFM slots determines the percentage of regulated flights with an ATOT inside the slot tolerance window.

The Actual Take-Off time of a flight can be determined when the NM received an ATC activation message from its departure airport. Therefore, the assessment is made only for those flights for which an activation message at the origin airport (FSA message) or a Departure message (DEP) is available.


Corrections may be made when issues are discovered as described in the Quality Assessment section of this document.


No comments.


This data is published by the Performance Review Body (PRB) of the Single European Sky. Every effort has been made to ensure that the information and analysis contained on this website are as accurate and complete as possible. Despite these precautions, should you find any errors or inconsistencies we would be grateful if you could please bring them to the Performance Review Unit’s attention.
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