Additional ASMA Time


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

The additional ASMA time is a proxy for the average arrival runway queuing time on the inbound traffic flow, during congestion periods at airports.

It is the difference between the actual ASMA time of a flight and a statistically determined unimpeded ASMA time based on ASMA times in periods of low traffic demand (see also unimpeded ASMA time - Methodology).

Uncertainty of approach conditions (e.g. pilot performance, landing clearance time, approach speed, wind conditions) makes traffic supply to runways a stochastic phenomenon. In order to ensure continuous traffic demand at runways and maximise runway usage, a minimum level of queuing is required. However, additional time in holding is detrimental to operations efficiency, fuel consumption and environment. Therefore, there exists a trade-off between approach efficiency and runway throughput.

As an output of the ATMAP Group, the additional ASMA time PI has been in use as a commonly agreed proxy for airport inefficiencies in the approach phase since 2008 and is compliant with the KPI definition in EU legislation.

Classification system

Additional ASMA time is classified per Member State, with a breakdown for each airport subject to performance monitoring within the SES performance scheme.

Sector coverage

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

Statistical concepts and definitions

The Arrival Sequencing and Metering Area (ASMA) is defined as a virtual cylinder with a 40-NM radius around the airport. The actual time spent by a flight between its last entry in the cylinder (Entry-time at 40 NM upstream) and the actual landing time (ALDT) is denoted ASMA transit time.

A Unimpeded ASMA time is determined for each group of flights with the same parameters (i.e. aircraft class, ASMA entry sector, arrival runway) and represents the transit time in non congested conditions.

The Additional ASMA time is the difference between the actual ASMA transit time and the unimpeded ASMA time calculated for non-congested conditions.

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 airports subject to performance monitoring within the SES performance scheme.

Reference area

The reference area is the Single European Sky Area.

Time coverage

2011 is the first year for which data is presented.

Base period

Not applicable.

Unit of Measure

The additional ASMA time is measured in minutes per IFR arrival [min/arr].

Reference period

  • The first reference period (RP1) covers the calendar years 2012 to 2014 inclusive.
  • The second reference period (RP2) covers the calendar years 2015 to 2019 inclusive.

Unless decided otherwise, the following reference periods shall be of five calendar years.

Institutional Mandate

Legal acts and agreements are established in the EU IR691/2010|Performance Regulation (691 / 2010) and Commission Implementing Regulation (EU) No 390 / 2013.


Release policy

Release calendar

Additional ASMA time 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

Quality assurance

Data validation is performed by CODA, on behalf of PRU, on each data delivery by airports, and data validation report are returned to the data providers.

Quality assessment

Raw data is cross-checked with various sources (Network manager, ANSP’s, airport operators, airport coordinators and air carriers). A quality threshold is established, and data that does not pass the quality threshold is rejected.

If a field is found to be blank, it is tried to fill the missing value from an alternative data source (i.e. a missing aircraft type in the airport data flow can be filled with information from the Network manager.)


The data is collected for all airports subject to performance monitoring within the SES performance scheme. Data completeness is determined each month as per the above-mentioned quality checks. Any missing data is reported to the provider.


The information is published for performance monitoring purposes in accordance with the relevant EU legislation.


The data is collected for the entire Single European Sky Area.

Accuracy and reliability

Overall accuracy

The accuracy of the measure is influenced by the availability of the entry point/runway configuration.

Sampling error

There is no sampling and therefore no sampling error.

Timeliness and punctuality


The information is published each month - in general around 30 days after the end of the month in question.


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


Comparability — geographical

The data is collected centrally by the EUROCONTROL Performance Review Unit with delegation to CODA and computed consistently for all airports subject to performance monitoring within the SES performance scheme.

The interpretation of the measure and comparisons across airports require due consideration of prevailing local circumstances (airport infrastructure, etc.)

Comparability over time

Comparisons over time are valid.


Coherence — cross domain

Checks have been carried out with a number of airports and there is generally a good level of coherence between the indicator results and the results from performance measurement systems of airport operators.

Coherence — internal

Data is fully coherent from an internal perspective.

Cost and burden

Not available.

Data revision

Subject to changes (i.e. airspace design), there might be a need to change unimpeded times accordingly.

Statistical processing

Source data

In accordance with EU legislation, the data is collected centrally for all the airports subject to performance monitoring within the SES performance scheme.

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

Frequency of data collection

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

Data collection

The data is collected by the EUROCONTROL Performance Review Unit and the Central Office for Delay Analysis (CODA).

Data validation

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

Data compilation

The ASMA area is defined as a 40-NM radius cylinder.

Calculation of the indicator


  • \(c\), a combination of aircraft class, ASMA sectors and arrival runway, as described in the Unimpeded ASMA time - Methodology,
  • \(f(c)\) a flight characterised by a combination \(c\),
  • \(\mathrm{AcASMA}(f(c))\) the actual ASMA transit time for a flight \(f(c)\), i.e. the elapsed time between the last entry of the flight \(f(c)\) in its ASMA sector and its actual landing time (ALDT),
  • \(\mathrm{UASMA}(c)\) the unimpeded ASMA time for a combination \(c\).

The additional ASMA time \(\mathrm{AdASMA}(f(c))\) is calculated for each flight \(f(c)\) as the difference between the actual ASMA transit time \(\mathrm{AcASMA}(f(c))\) of the flight and the unimpeded ASMA time \(\mathrm{UASMA}(c)\): \[ \mathrm{AdASAM}(f(c)) = \mathrm{AcASMA}(f(c)) - \mathrm{UASMA}(c) \]

The additional ASMA time \(\mathrm{AdASMA}(c)\) for a given combination \(c\) is the average of the additional ASMA time \(\mathrm{AdASMA}(f(c))\) of all the flight \(f(c)\) characterised by that combination \(c\).

The additional ASMA time \(\mathrm{AdASMA}\) for a given airport is the weighted average of the additional ASMA time \(\mathrm{AdASMA}(c)\), for all the combinations \(c\) at that airport with their probability of occurrence.


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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