## Contacts

 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 Fusée1130 BrusselsBelgium Contact e-mail address PRU-Support@eurocontrol.int

## Statistical presentation

### 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 methodology documentation).

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.

### 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.

### Sector coverage

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

### 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.

### 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.

Not applicable.

## Unit of Measure

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

## 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.
• The third reference period (RP3) covers the calendar years 2020 to 2024 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), Commission Implementing Regulation (EU) No 390 / 2013 and Commission Implementing Regulation (EU) 2019/317.

## Release policy

### Release calendar

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

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).
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

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

### Quality assurance

Data validation is performed by the Central Office for Delay Analysis (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.)

### Completeness

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.

## Relevance

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

## Accuracy and reliability

### 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).

### Sampling error

There is no sampling and therefore no sampling error.

## Timeliness and punctuality

### Timeliness

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

### Punctuality

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

## Comparability

### Comparability — geographical

The data is collected centrally by the EUROCONTROL Performance Review Unit (PRU) with delegation to the Central Office for Delay Analysis (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

### 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.

Not available.

## Data revision

Subject to changes (i.e. infrastructure), 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 (PRU) and the Central Office for Delay Analysis (CODA).

### Data validation

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

### Data compilation

#### Calculation of the indicator

Let

• $$c$$, a combination of departure runway and group of stands, as described in the methodology for unimpeded taxi-out time,
• $$f(c)$$ a flight characterised by a combination $$c$$,
• $$\mathrm{AcTXOT}(f(c))$$ 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),
• $$\mathrm{UTXOT}(c)$$ the unimpeded taxi-out time for a combination $$c$$.

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

$\mathrm{AdTXOT}(f(c)) = \mathrm{AcTXOT}(f(c)) - \mathrm{UTXOT}(c)$

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

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