Eurostat, the statistical office of the European Union

E3: Transport

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The air transport performance cover passenger-kilometres (PKM) for passenger transport and tonne-kilometres (TKM) for freight transport that are 'territorialised' to the countries and the EU.

The ‘territorialised’ air transport performance is a concept used only for comparing the transport modes' activity at the EU or at a country level. The resulting statistics are not comparable with statistics on energy consumption in transport or with GHG emissions as these are based on different methodologies.

Eurostat collects air transport data expressed in tonnes and in number of passengers carried between pairs of airports but the methodology for calculation and ‘territorialisation’ of air transport performance in tonne-km (TKM) and passenger-km (PKM) has been developed by Eurostat.  Passenger-km and tonne-km are calculated by Eurostat on the basis of the collected air transport data expressed in tonnes and in number of passengers carried between pairs of airports with the help of the distance matrix (shortest route), developed and maintained by Eurostat. The distance matrix contains as well a so-called 'territorialisation tool' that allows attributing the calculated TKM and PKM to the countries overflown on the route.

The distance for each country is based on its national airspace, which includes territorial waters of 12 nautical miles off its coast. 

The 'territorialised' TKM and PKM are presented at a country and at the EU level with the following breakdowns:

• Intra-EU that combines national (domestic) and international intra-EU transport
• International Extra-EU transport
• Overflown

Concrete examples and description of these breakdowns can be found in the diagram (see Annexes) ; they are explained in point 18.5 below and in further details in the 'Methodology for territorialisation of air transport', pages 12 and 13 (in the annex below).

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Transport

Eurostat collects air transport data expressed in tonnes and in number of passengers carried between pairs of airports according to Regulation (EC) No 437/2003 of the European Parliament and of the Council of 27 February 2003 on statistical returns in respect of the carriage of passengers, freight and mail by air.

The methodology for calculation and ‘territorialisation’ of air transport performance in TKM and PKM has been developed by Eurostat:

‘Territorialisation’ means that the transport is performed within the territory of a country. In terms of air transport, 'territorialisation' means that the transport performed in the air space is allocated to the countries overflown on each air transport route. This principle brings as close as possible air to the other transport modes in order to compare shares of each transport mode into the total transport performance in the European Union and also at national level. This is called the ‘modal split’ between the different transport modes.

 ‘Transport performance’ is measured in tonne-kilometres (TKM) for freight/mail and passenger-kilometres for passengers (PKM). A tonne-kilometre is defined as one tonne of freight flying for one kilometre; a passenger-kilometre is defined as one passenger flying for one kilometre. First, the total TKM or PKM on a route are calculated based on passengers/freight transported between pair of airports and a distance matrix.  Then, the calculated TKM/PKM are ‘territorialised’ by allocating them proportionally to the countries overflown, according to the distance flown over each country.

Eurostat maintains a database of distances (distance matrix) between EU airports, and between EU airports and World-wide airports. The distances are based on the ‘greater-circle’ distance, which is the shortest distance between two points on the surface of a sphere (i.e. the shortest possible flight path between the airport of origin and the airport of destination). This shortest distance is then split into distance legs for each country overflown during the flight in order to 'territorialise' the transport performance.

The distance for each country is based on its national airspace, which includes territorial waters of 12 nautical miles off its coast. 

Additional definitions of the terms used in the frame of the statistics on air transport are available in the "Glossary for Transport Statistics" (see Annex at the bottom of this page).

The air data on passengers and freight/mail transported between pair of airports, used for the calculations of data in this domain are collected by different data providers at airport level.

As the Regulation (EC) N°1358/2003, implementing Regulation N°437/2003 of the European Parliament and of the Council on statistical returns in respect of the carriage of passengers, freight and mail by air, defines four categories of Community airports, the reported data used for compiling the statistics presented here, cover categories 2 and 3 that refers to airports with more than 150 000 passenger units per year. According to this legal act, data are reported for commercial air services that means that military flights, flight activities relating to aerial work, hospital flights and any other non-commercial flights are excluded.

Currently air transport data on passengers and freight/mail are reported by the EU countries, three EFTA countries (Switzerland, Norway and Iceland) and few candidate countries (Turkey, North Macedonia, Montenegro and Serbia). Data reported by all these countries are used in the calculation and territorialisation of air transport PKM and TKM data.

Data on PKM and TKM are disseminated for the EU Member States and two EFTA countries Norway and Switzerland. EU aggregates are also provided.

From 2008 onwards.

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Transport performance is measured in tonne-kilometres (TKM) for freight/mail and passenger-kilometres for passengers (PKM).

Calendar year

The data are based on the Regulation (EC) No 437/2003 of the European Parliament and of the Council of 27 February 2003 on statistical returns in respect of the carriage of passengers, freight and mail by air.

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Regulation (EC) No 223/2009 on European statistics (recital 24 and Article 20(4)) of 11 March 2009 (OJ L 87, p. 164), stipulates the need to establish common principles and guidelines ensuring the confidentiality of data used for the production of European statistics and the access to those confidential data with due account for technical developments and the requirements of users in a democratic society.

Only the airline information data is subject to confidentiality. The data providers may deliver this information with a higher level of aggregation to avoid confidentiality constraints at national level.

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In line with the Community legal framework and the European Statistics Code of Practice Eurostat disseminates European statistics on Eurostat's website (see item 10 - 'Accessibility and clarity') respecting professional independence and in an objective, professional and transparent manner in which all users are treated equitably. The detailed arrangements are governed by the Eurostat protocol on impartial access to Eurostat data for users.

Annual.

Normally not planned.

Modal split is presented in the Statistics Explained article on Freight transport statistics - modal split.

Please consult free data on-line.

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Internet address: http://ec.europa.eu/eurostat

The methodology for calculating and territorialising PKM and TKM for air transport at countries level can be found in the document 'Methodology for territorialisation of air transport' (see Annex at the bottom of this page).

The Reference Manual on Air Transport Statistics (see link at the bottom of this page) contains detailed methodological information as well as background information on the implementation of the legal acts and on how passengers and freight/mail data are processed and disseminated by Eurostat.

The Reference Manual on Air Transport Statistics (see link at the bottom of this page) includes a section describing the quality checks applied to the incoming data as well as showing the results of the quality analysis of the last full data collection year available.

Data quality is ensured by the implementation of a common and well established methodology for the data collection and compilation at country level. Data is subsequently validated in Eurostat by applying different controls on the incoming data, before and after treatment, as well as by cross-checking partner countries figures (mirror statistics).

Data quality on air passengers and freight/mail is generally high. Few problems are detected on data treatment and if so, the countries involved are immediately contacted to solve the problem. Annually, a data quality report is prepared with a summary of the main findings affecting quality as well as showing the solution adopted and the level of the existing differences. It is provided to each country in order either to correct the existing data or to improve the data quality for the future data transmissions.

The main users are evaluated to be the European Commission, international and governmental bodies.

The ‘territorialised’ air transport performance is a concept developed to be used mainly for comparing shares (modal split) of the transport carried out by the different modes of transport within the total transport performance at the EU level or countries level. The resulting statistics are not comparable with statistics on energy consumption in transport or with GHG emissions as these are based on different methodologies.

Eurostat does not carry out a specific satisfaction survey. Methodological issues or other aspects of further development are a subject of discussion with the relevant national authorities, other services of the Commission or, in some cases, other institutions.

There is an obligation of data provision for the Member States and, as a consequence, there are very few gaps in the data provision. Data are based on the reports provided by the countries, therefore, they reflect any break in series appearing due to a country starting to report data (i.e. Turkey in 2012).

Overall accuracy of the data on passengers and freight/mail carried is generally good. Regular comparisons with other relevant international sources (ICAO, airports data) show a high level of comparability.

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The data collection on passengers and freight/mail, followed by calculation and 'territorialisation' of air transport PKM and TKM takes between a year and year and a half after the reference period.

A majority of countries deliver the data on passengers and freight/mail earlier than the t+6 months regulatory deadline. The rest of the countries respect the deadline for data provision with some occasional exceptions.

Data comparability across countries is very high. This is ensured by the implementation of a common methodology. In addition, the so-called "mirror checks" allow comparing the data declared by partner reporting airports and finding possible inconsistencies that are corrected as far as possible.

Comparability over time is normally high. The present methodological approach on collecting data on passengers and freight/mail has been applied for a number of years now and it is well understood and applied at airport and country level. However, data availability over time depends on each country (i.e. there has been an increase in the number of reporting airports over time, or a country has started providing data after 2008) and that may lead to a certain break in series. For example, Turkey started reporting air passengers and freight/mail data from reference year 2012, North Macedonia - from 2015, Montenegro - from 2016 and Serbia - from 2015.

Data coherence across the domain is good as detailed data at airport level are available and this information allows the implementation of different quality checks to ensure the coherence of the data.

The quality checks include mirror statistics, time series checks and inter-datasets checks.  These quality checks detect data that could possibly be in error. Further investigation is recommended for data that fail these checks. Therefore, the internal consistency of the data is generally high.

The calculation of data is done by Eurostat and does not apply any cost and burden at national level.

Data revisions are taken into account and processed when provided by the national competent authorities.

Methodology on collecting passengers and freight/mail has been settled down in the above mentioned regulation following existing agreements. Methodology on agreeing a method to calculate and 'territorialised' transport performance (in tonne-km and passenger-km) that allows comparison of air transport to other modes has been discussed and agreed within the European statistical system (ESS).

Data on passengers and freight/mail are collected and/or compiled by the competent national authorities, which can be for instance the Statistical Office or the Civil Aviation Authorities. Original data sources are normally the airports organisations or enterprises.

Data on passengers and freight/mail are normally collected on a monthly basis, however, for calculating transport performance data are aggregated at annual level.

Data on passengers and freight/mail are transmitted to Eurostat using the eDAMIS engine tool following the transmission format foreseen in Regulation (EC) 1358/2003 (Commission Regulation).

Validation of data on passengers and freight/mail takes place at several levels of the data processing. The first step is the automatic validation during the integration, and the second step is the quality checks when data has been integrated. Three types of quality checks are made on the datasets of passengers and freight/mail received for national and international transport.

• Consistency over time

This check is made in order to detect unlikely increase or decrease of transport at one of the reporting airports. This check is applied separately for international and national transport.

• Mirror checking

These quality checks are performed in order to compare the consistency between two partner declarations. They are run both for national and international declarations at city level. This means that the reported data have been first aggregated at city levels and then compared. This allows detecting and solving potential problems of wrong airport code attribution.

• Missing routes

This check allows detecting the routes between two declaring airports where only one of them has declared the information.

Possible data errors in passengers or freight/mail carried that are detected at this stage are communicated to the countries for checking purposes. All corrections of errors are documented. Sometimes it might be prudent to return the data to the countries for correction and re-supply. Data that are re-supplied are then re-validated, before further quality checking.

Eurostat is using an air distance matrix containing great circle distances (minimum distance on a spherical line) between the different pairs of airports to calculate TKM or PKM for air transport. In addition, the distance matrix contains a 'territorialisation tool' that allows attributing the overflown TKM or PKM to the countries or the EU. The 'territorialisation tool' applied is an estimation method based on certain assumptions.

The main features of Eurostat’s territorialisation tool for air transport are:

• In terms of the 'territoriality principle', the 'national territory' of a country with respect to air transport is defined as the land mass of the country, including islands, together with the adjacent national territorial waters (12 nautical miles from the coastline), if any. This corresponds to the definition of the national airspace.
• A tonne-kilometre with respect to air transport is defined as one tonne of freight flying for one kilometre. Similarly, a passenger-kilometre with respect to air transport is defined as one passenger flying for one kilometre.
• The distance of each flight route, connecting a pair of airport, is defined as the great circle distance between the airport of origin and the airport of destination. The ‘great circle distance’ is the shortest distance between two points on a sphere (globe).  This distance is then proportionally assigned to each country overflown on the route, according to the distance flown over the national territory (i.e. through the national airspace) of the respective countries.
• For each airport pair, the number of passengers or tons of freight/mail carried is multiplied by the distance flown over each individual country’s territory, producing passenger-kilometres and tonne-kilometres for each country according to the 'territoriality principle'.
• Subtracting the sum of distances flown over the countries from the total distance (for an airport pair) leaves the distance that cannot be ‘territorialised’. This non-attributable distance is either flown over international waters or over countries that are not included in the territorialisation tool (please refer to 'Methodology for territorialisation of air transport' in annex).

At country level, data are presented with the following breakdowns:

• 'Intra-EU' that combines National transport + International intra-EU transport. This covers transport between the concerned country and EU Member States.
• 'Extra-EU' that is transport between the concerned country and non-EU countries.
• 'Overflown' that is transport between other countries (EU countries or non-EU countries reporting data to Eurostat) that passes through the airspace of the concerned country, without departing or landing at its airports.

Eurostat calculates as well EU aggregates, with following breakdowns:

• 'Intra-EU' that is National + International intra-EU transport, that is transport between EU Member States.
• 'Extra-EU' that is transport between EU Member States and non-EU countries.
• 'Overflown' that is transport between non-EU countries (reporting data to Eurostat) that passes through the airspace of one or more Member States without departing or landing at their airports.

The total TKM and PKM calculated for the EU aggregates are equal to the sum of the Member States totals. However, the sum of the presented breakdowns of the Member States are not equal to the respective breakdowns for the EU aggregate as the concept differs. For better understanding, please, refer to the diagram in annex.

In the process of calculation, the problem of double counting is addressed. For each aggregate it is necessary to start at the airport level in order to identify the mirror declarations, i.e. the airport routes for which both airports report the volume, since these constitute the routes where the problem of double counting occurs.

The calculations of tonne-km and passenger-km for the countries or for the EU, are based on all data reported to Eurostat (as mentioned in point 3.6) that covers as well some non-EU countries (except data reported by the United Kingdom until reference period 2019). It is important to bear in mind that the category ‘overflown’ is particularly influenced by the availability of data for non-EU countries and their inclusion or not in the calculations. For example, for the EU aggregate, the exclusion of the data reported by the UK from the calculations has as an effect a reduction of total passenger-km between 6% and 10% in the period 2008- 2019, while for the category ‘overflown’ it reaches between 60% and 80% for the period 2008-2019. The impact on total tonne-km corresponds to a reduction between 13% and 15% in the period 2008-2019, while for the category ‘overflown’, the reduction reaches between 82% and 86% for the period 2008-2019.

Further details of the calculation of TKM and PKM and their 'territorialisation' can be found in the 'Methodology for territorialisation of air transport' (see annex).

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