Additional taxi-out time

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1. Contact
1.1 Contact organisation EUROCONTROL: The European organisation for the safety of air navigation.
1.2 Contact organisation unit Directorate Single Sky - Performance Review Unit (DSS/PRU)
1.3 Contact name Performance Review Unit - EUROCONTROL
1.5 Contact mail address 96 Rue de la Fusée
1130 Brussels
BELGIUM
1.6 Contact e-mail address NSA-PRU-Support@eurocontrol.int
1.7 Contact phone number +32 2 729 39 56
2. Metadata update
2.1. Metadata last certified not applicable
2.2. Metadata last update 01 November 2016

3. Statistical presentation

3.1. Data description

The additional taxi-out time is a proxy for the average departure runway queuing time on the outbound traffic flow, during congestion periods at airports.
It is the difference between the actual taxi-out time of a flight and a statistically determined unimpeded taxi-out time based on taxi-out times in periods of low traffic demand (see also related technical note).

Uncertainty of take-off clearance time and aircraft arriving time at runway holding stop bars 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 is detrimental to taxi-out efficiency, fuel consumption and environment. Therefore, there exists a trade-off between taxi-out efficiency and runway throughput.

When monitoring taxi-out performance at airports, it is to be stressed that the goal is not to reduce taxi time to an unimpeded time - as this could negatively impact on runway throughput - but rather to reduce additional taxi-out time and associated fuel burn to the strict minimum.

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

3.2. Classification system

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

3.3. Sector coverage

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

3.4. Statistical concepts and definitions

The Taxi-out time is defined as the time spent by a flight between its actual off-block time (AOBT) and actual take-off time (ATOT).

The Unimpeded taxi-out time is an average taxi-out time when there is no congestion. There is one unimpeded time by departure airport, departure runway and departure stand.

The Additional taxi-out time is the difference between the actual taxi-out time and the unimpeded taxi-out time.

3.5. Statistical unit

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

3.6. Statistical population

The statistical population is the set of airports subject to performance monitoring within the SES performance scheme.

3.7. Reference area

The reference area is the Single European Sky Area.

3.8. Time coverage

2011 is the first year for which data is presented.

3.9. Base period

Not applicable.

4. Unit of measure

Additional taxi-out time is measured in minutes per IFR departure [min/dep].

5. 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.

6. Institutional Mandate

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

7. Confidentiality


8. Release policy

8.1. Release calendar

Taxi-out additional time data is released monthly with yearly aggregates.

8.2. Release calendar access

Not applicable.

8.3. User access

Information is disseminated to the general public via the EUROCONTROL website.

9. Frequency of dissemination

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

10. Dissemination format

The information is available on the EUROCONTROL website.

11. Accessibility of documentation

11.1. Documentation on methodology

As per the pertaining regulations (see Institutional Mandate).
For technical questions not addressed in Statistical processing please contact: NSA-PRU-Support@eurocontrol.int.
Additional definitions of the terms used in the frame of the this KPI are available in the Glossary.

11.2. Quality documentation

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

12. Quality Management

Although data providers are responsible for data quality, the EUROCONTROL Performance Review Unit performs data validation and quality checks.

12.1. 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.

12.2. 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.

12.3. Completeness

The data is collected for all the 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.


13. Relevance

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

14. Accuracy and reliability

14.1. Overall accuracy

The accuracy of the measure is influenced by the availability of the stand/runway configuration and the type of AOBT recording at the airports (manual vs. automated).

14.2. Sampling error

There is no sampling and therefore no sampling error.

15. Timeliness and punctuality

15.1. Timeliness

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

15.2. Punctuality

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

16. Comparability

16.1. 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.).

16.2. Comparability over time

Comparison over time is valid.

17. Coherence

17.1. 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.

17.2. Coherence — internal

Data is fully coherent from an internal perspective.

18. Cost and burden

Not available.

19. Data revision

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

20. Statistical processing

20.1. Source data

In accordance with EU legislation, the data is collected centrally for all 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.

20.2. Frequency of data collection

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

20.3. Data collection

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

20.4. Data validation

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

20.5. Data compilation

Calculation of the indicator

Let

  • c, a combination of departure runway and group of stands, as described in the technical note for unimpeded taxi-out time,
  • f(c) a flight characterised by a combination c,
  • AcTXOT(f(c)) the actual taxi-out time for a flight f(c), i.e. the elapsed time between the off-block time (AOBT) of the flight f(c) and its actual take-off time (ATOT),
  • UTXOT(c) the unimpeded taxi-out time for a combination c.

The additional taxi-out time AdTXOT(f(c)) is calculated for each flight f(c) as the difference between the actual taxi-out time AcTXOT(f(c)) of the flight and the unimpeded taxi-out time UTXOT(c) :

AdTXOT(f(c)) = AcTXOT(f(c)) - UTXOT(c)

The additional taxi-out time AdTXOT(c) for a given combination c is the average of the additional taxi-out time AdTXOT(f(c)) of all the flight f(c) characterised by that combination c.

The additional taxi-out time AdTXOT for a given airport is the weighted average of the additional taxi-out time AdTXOT(c), for all the combinations c at that airport with their probability of occurrence.

20.6. Adjustment

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

21. Comment

Disclaimer

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.

The information may be copied in whole or in part providing that the copyright notice and disclaimer are included. The information may not be modified without prior written permission from the PRB. The views expressed herein do not necessarily reflect the official views or policy of EUROCONTROL or of the European Commission, which make no warranty, either implied or express, for the information contained on this website, neither do they assume any legal liability or responsibility for the accuracy, completeness or usefulness of this information. The PRB reserves the right to change or amend the information provided at any time and without prior notice.

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