Guidance

Aviation statistics: notes and definitions

Updated 23 October 2024

About this release

These notes and definitions accompany the statistical releases Transport Statistics Great Britain and Air passenger experience of security screening, and provide background information for the aviation data tables.

This document includes information on sources, data quality, definitions, and general information about the tables.

Data sources

All the statistics in this series are collected by organisations external to the Department for Transport (DfT) and are outside the scope of accredited official statistics (previously National Statistics).

Most of the tables published are based on data collected by the Civil Aviation Authority (CAA):

• tables AVI0101, AVI0102, AVI0103, AVI0105 and AVI0109 are based on returns submitted to the CAA by airports or airport operators
• tables AVI0201 and AVI0203 are based on returns submitted to the CAA by UK registered airlines
• tables AVI0106 to AVI0108 and AVI0501 to AVI0505 are based on data collected from the CAA Departing Passenger Survey
• table AVI0401 is compiled from data supplied by the CAA’s Safety Data Unit

The following tables are based on data collected by other organisations:

• table AVI0301 is based on data supplied by the International Civil Aviation Organization (ICAO)
• table AVI0402 is based on data collated by the UK Airprox Board

Coverage

The terms ‘UK airports’ and ‘UK airlines’ cover the airports and airlines which submit returns to the CAA. These include all major UK airports that receive commercial traffic and all UK registered airlines that carry passengers or freight on a commercial basis.

Air taxi operations (small commercial aircraft making short flights on demand) are excluded from all tables on activity at UK airports except for the early time series (1950 to 1990) in Table AVI0101.

Traffic reported by airports in the Channel Islands are excluded from AVI01 series data tables. Traffic reported by Isle of Man Airport is included in table AVI0101 until 1989, but excluded from all other AVI01 series data tables.

Activity at UK airports (AVI01 series)

Information on tables AVI0101 and AVI0102

These tables show the number of air transport movements (landings and take-offs of aircraft engaged in commercial air transport), terminal passengers (arrivals and departures) and freight handled (set down and picked up) at UK airports.

In table AVI0101, prior to the year 1990, figures are derived from the annual Airport Statistics series published by the CAA:

• air transport movements: CAA Airport Statistics, Table 4
• terminal passengers: CAA Airport Statistics, Table 10.1 and 10.2
• freight handled: CAA Airport Statistics, Table 14

For figures from 1990 onwards, figures are derived from a version of the CAA Airport Statistics held by DfT. The underlying dataset held by DfT is the same dataset that produces the CAA Airport Statistical tables outlined above, however due to differences in data processing methods figures might vary slightly between the 2 versions of the data.

In table AVI0102, the airport list is split into 2 different categories of airports:

Reporting airports: these are airports that provide full statistical data on the movement of aircraft engaged in the transport of passengers, freight or mail on a commercial basis.

Summary airports: these airports do not submit full statistical returns on handling activity to the CAA and are not included in the version of CAA Airport Statistics held by DfT. These are typically small airports. As a result, these figures are still derived from published CAA Airport Statistics tables outlined above.

The terms used in these tables are defined as follows:

Air transport movements: all landings and take-offs of aircraft engaged in the transport of passengers, freight or mail on commercial terms.

Domestic services: services flown entirely within the United Kingdom, excluding the Crown Dependencies.

International services: services flown between the United Kingdom and places outside, including the Crown Dependencies.

Scheduled services: services performed according to a published timetable, available for use by members of the public.

Non-scheduled services: air transport movements other than scheduled services.

Terminal passengers: all revenue and non-revenue passengers joining or leaving an aircraft at a UK airport. A passenger travelling between 2 reporting airports is counted twice, once at each airport. A passenger who changes from one aircraft to another is a terminal passenger on both arrival and departure.

Freight: the weight of other property carried on an aircraft excluding mail and passengers’ and crews’ permitted baggage. Freight in transit through the airport on the same aircraft is excluded.

Information on table AVI0103

Table AVI0103 is derived from the CAA Punctuality Statistics. The CAA has historically compiled punctuality data for 5 London airports (Heathrow, Gatwick, Stansted, Luton and London City) and 5 regional airports (Manchester, Birmingham, Glasgow, Edinburgh and Newcastle). From 2015, the CAA started collecting data for a larger number of airports.

For table AVI0103, “on-time” performance is defined as flights that arrive or depart early or up to 15 minutes late in relation to their scheduled arrival or departure times. The measure of punctuality is derived from the difference between actual gate time and planned gate time of flights.

Actual gate times of operation are supplied by airport operators to the CAA. Planned times are supplied by Airport Coordination Limited or the airport operators themselves and include changes made up to 30 minutes before operation.

In early 2017, the CAA reviewed the methodology followed to calculate delays with a view to ensuring punctuality metrics are accurate, reliable, and present a fair picture of aviation performance. The review recommended that the CAA should move from an estimated gate delay approach to calculating actual gate delay. This has been achieved by the collection of data on actual gate times from airport, thereby removing the need to use estimated taxi times. Figures from the new methodology were implemented from January 2018, creating a discontinuity in the time series.

Information on table AVI0104

This table was discontinued in 2013. Detailed aviation forecasts for 2017 are available on the DfT website.

Information on table AVI0105

This table provides an analysis of the number of international terminal passengers handled at UK airports by last or next country travelled to.

From the 2017 publication year, the figures in this table are derived from the version of the CAA Airport Statistics held by DfT. Figures are based on the country of the immediate last (for arrivals) or next (for departures) stop on the aircraft’s journey. This may not necessarily be the ultimate origin or destination of the passenger. The numbers of international passengers reported in Table AVI0105 are consistent with those reported in Table AVI0102. Countries travelled to or from are presented in the following categories which are based on the United Nations (UN) standard country codes for statistical use:

European Union: figures are presented for the 27 individual countries in the European Union.

Other Europe: this includes all countries classified as Europe by the UN for statistical purposes, other than those that form part of the European Union. This also includes movements between UK reporting airports and airports in the UK Crown Dependencies (Channel Islands and Isle of Man).

North America: this includes all countries classified as North America by the UN for statistical purposes.

Rest of the World: this includes all other countries, with additional breakdowns for geographical sub-regions. Only those countries with a large number of international passenger movements to and, or from the UK are presented individually.

Oil Rigs: this includes passenger movements to and, or from off-shore platforms.

Information on tables AVI0106, AVI0107, and AVI0108

These tables are based on data from the CAA Departing Passenger Survey. This is a survey of departing passengers carried out at selected UK airports. Results may differ slightly from published CAA reports due to minor differences in data processing.

Results are given for the 5 UK airports which have been included in the survey every year since 2000: Heathrow, Gatwick, Stansted, Luton and Manchester. These airports were the top 5 in the UK in 2023 for numbers of passengers handled, and are regularly amongst the UK airports with the highest levels of passenger demand. In more recent years, a small number of additional airports have also been surveyed and data for these airports is available on request from the CAA.

Terms used in table AVI0106 are defined as follows:

Transfer passengers: passengers who change aircraft at the airport and have no other reason for visiting the airport.

Terminating passengers: passengers who arrive at or depart from an airport by surface modes of transport.

In table AVI0107, where more than one mode of transport is used to travel to an airport, the final mode is presented.

Information on table AVI0109

This table contains a map visualising the location of UK reporting and summary airports.

In table AVI0109, the airport list is split into 4 different categories of airports:

Reporting airports: these are airports that provide full statistical data on the movement of aircraft engaged in the transport of passengers, freight or mail on a commercial basis.

Former reporting airports: these are airports which no longer provide reporting figures for air traffic handled, but have done so within the last 10 years.

Summary airports: these airports do not submit full statistical returns on handling activity to the CAA and therefore are not included in the version of the CAA Airport Statistics held by DfT. These are typically small airports.

Former summary airports: these are airports which no longer provide summary figures for air traffic handled, but have done so within the last 10 years.

Activity by UK airlines (AVI02 series)

Information on table AVI0201

Table AVI0201 is derived from the CAA UK Airline Statistics annual series. The table shows the carriage of revenue passengers and cargo (freight and mail) on services flown by UK airlines worldwide. The table includes scheduled and non-scheduled services, but excludes air-taxi operations and sub-charter operations performed on behalf of UK airlines.

The following metrics are included:

Aircraft kilometres flown: calculated by multiplying the number of flights performed by the stage distance.

Passengers uplifted: calculated by counting each revenue passenger on a particular flight (with a single flight number) once only and not repeatedly on each individual stage of that flight.

Passengers kilometres flown: calculated by multiplying the number of revenue passengers carried on each stage flight by the stage distance (also known as seat kilometres used).

Passenger seat occupancy: calculated by dividing the passenger kilometres flown by seat-kilometres available and expressing it as a percentage.

Cargo uplifted (freight and mail): calculated by counting each tonne of revenue freight or mail on a particular journey (with a single flight number) once only and not repeatedly on each individual stage of that flight.

Cargo tonne-kilometres flown (freight and mail): calculated by multiplying the number of tonnes available for the carriage of revenue cargo load (freight and mail) on each flight stage by the stage distance.

A flight stage is operated from when an aircraft takes off to when it next lands.

The terms used in table AVI0201 are defined as follows:

International services: in these tables, these services are flown between the United Kingdom, Isle of Man or Channel Islands and points in other countries, or between 2 non-United Kingdom airports. This differs from the definition of ‘international services’ used in tables AVI0102 and AVI0105 which does not include services between the Crown Dependencies and points in other countries, or flights between 2 non-United Kingdom airports.

Domestic services: these services are flown entirely within the United Kingdom, Isle of Man and Channel Islands. This differs from the definition of ‘domestic services’ used in tables AVI0102 and AVI0105 which treats services between the United Kingdom and the Crown Dependencies as international services.

Scheduled services: these services are performed according to a published timetable available for use by members of the public.

Non-scheduled services: all services other than scheduled services.

Information on table AVI0202

This table was discontinued in 2011. Data on the fleet operated by UK airlines can be found as part of the CAA Airline Statistics collection.

Information on table AVI0203

Table AVI0203 is derived from returns submitted to the CAA by UK registered airlines. This table shows the number of personnel employed by UK airlines in the UK and overseas, as at the end of the calendar year. Personnel employed by companies performing solely air-taxi operations are excluded.

The terms used in AVI0203 are defined as follows:

Pilots and co-pilots: licensed pilots serving in any piloting capacity, including pilots-in-command.

Other cockpit personnel: includes flight engineers, radio operators and navigators.

Cabin attendants: cabin attendants including pursers, stewards, and flight attendants.

Maintenance and overhaul personnel: ground personnel, including supervising, planning and inspection personnel at maintenance and overhaul workshops. Also includes stores and supplies personnel, timekeepers and accounting personnel at maintenance and overhaul workshops.

Tickets and sales personnel: personnel engaged in ticketing, sales, and promotional activities.

All other personnel: personnel on payroll not included in any of the above 5 categories, such as administrative personnel at headquarters.

Major airports worldwide (AVI03 series)

Information on table AVI0301

Table AVI0301 gives a comparison of the activity at some of the world’s major airports. Data for this table is taken from the International Civil Aviation Organization (ICAO).

Information on table AVI0302

This table was discontinued in 2022.

Aviation accidents and incidents (AVI04 series)

Information on table AVI0401

Table AVI0401 includes deaths, serious and minor injuries where an aircraft was engaged in airline, air taxi, general aviation (including private flights) and other commercial (including training) operations.

Terms used in table AVI0401 are defined as follows:

Commercial Air Transport: passenger and cargo operations involving either fixed wing aircraft with Maximum Take-Off Weight (MTOW) above 5,700kg, or rotary wing aircraft with MTOW above 3,175kg.

Other (such as general aviation): powered fixed wing or rotary wing aircraft of any MTOW including (but not limited to) executive, private and training flights, and small (fixed wing under 5,700kg, rotary wing under 3,175kg) aircraft undertaking passenger or cargo flights specifically.

Information on table AVI0402

An aircraft proximity hazard (AIRPROX) is a situation in which, in the opinion of a pilot or controller, the distance between aircraft as well as their relative positions and speed have been such that the safety of the aircraft was or may have been compromised. AIRPROX can occur between various combinations of commercial, military, and private aircraft. The numbers of AIRPROX incidents involving commercial transport aircraft are shown separately in the table. All AIRPROX reports are assessed and, following guidelines given by the ICAO, the degrees of risk involved are categorised as ‘risk of collision’, ‘safety not assured’, ‘no risk of collision’, and ‘risk not determined’. An additional category, ‘non-event’ was introduced in 2011.

Air passenger experience of security screening (AVI05 series)

Information on tables AVI0501 to AVI0505

The CAA Departing Passenger Survey is undertaken to obtain information about air travellers that cannot be collected on a routine basis from the air transport industry. The survey includes questions on passenger demographics, journey purpose, routes flown and means of transport to the airport.

The CAA uses its own interviewers to conduct the survey and it runs continuously throughout the year at selected UK airports. Only departing passengers are interviewed, with interviews taking place at the departure gate.

In 2023, a set of 4 questions relating to security screening was sponsored by the DfT to monitor passengers’ experiences at UK airports:

• How satisfied are you with your experience of the security screening used at the airport today?

• What aspect of the security screening were you least satisfied with?

• For how long, in minutes, did you queue when waiting to be security screened?

• How strongly do you agree or disagree with the following statement: “Any inconvenience caused by the security screening was acceptable”?

The questions relate to the security screening process used when the passenger enters the departure lounge. This covers the bag x-ray machine, the metal detector, and the body and bag searches.

Security screening questions were asked of a sub-sample of passengers responding to the main survey at Heathrow, Gatwick, Luton, Manchester and Stansted. The same set of questions was asked at Heathrow, Manchester and Stansted in 2010 and at Heathrow, Gatwick, Luton, Manchester and Stansted from 2011 to 2019. In 2008 and 2009, a longer set of questions on passenger experience was asked at a selection of airports including Heathrow, Manchester and Stansted; this included 3 of the 4 questions asked in 2010 to 2015. Security screening questions were not asked of passengers at any airports in 2020, 2021 and 2022, due to the COVID-19 pandemic.

Table 1 provides a full list of the airports at which passengers were asked security screening questions in each year since 2008.

Table 1: Years in which passengers at airports were asked security screening questions

Year	Heathrow	Gatwick	Luton	Manchester	Stansted	Birmingham	Bristol	Edinburgh	Glasgow	Inverness	Leeds Bradford	London City
2008	Yes	No	No	Yes	Yes	No	Yes	No	No	No	No	No
2009	Yes	Yes	Yes	Yes	Yes	No	No	Yes	No	Yes	No	No
2010	Yes	No	No	Yes	Yes	No	No	No	No	No	Yes	No
2011	Yes	Yes	Yes	Yes	Yes	No	No	No	No	No	No	No
2012	Yes	Yes	Yes	Yes	Yes	No	No	No	No	No	No	No
2013	Yes	Yes	Yes	Yes	Yes	No	No	Yes	Yes	No	No	No
2014	Yes	Yes	Yes	Yes	Yes	No	No	No	No	No	No	No
2015	Yes	Yes	Yes	Yes	Yes	No	No	No	No	No	No	No
2016	Yes	Yes	Yes	Yes	Yes	No	No	No	No	No	No	No
2017	Yes	Yes	Yes	Yes	Yes	No	No	No	No	No	No	No
2018	Yes	Yes	Yes	Yes	Yes	No	No	No	No	No	No	No
2019	Yes	Yes	Yes	Yes	Yes	Yes	No	No	No	No	No	Yes
2020	No	No	No	No	No	No	No	No	No	No	No	No
2021	No	No	No	No	No	No	No	No	No	No	No	No
2022	No	No	No	No	No	No	No	No	No	No	No	No
2023	Yes	Yes	Yes	Yes	Yes	No	No	No	No	No	No	No

Changes to question wording and response options

At the beginning of 2016, there were changes to the way in which passengers’ responses to some questions were recorded, with a transition from paper to an electronic device. This transition affected the 2 ‘satisfaction’ questions, with response options being rephrased or expanded. Summarised figures prior to 2016 are therefore reported separately for these questions.

In 2023, response options to the ‘queue time’ question were amended, with passengers asked to provide an estimate using time bands for queue durations of 10 minutes or longer, rather than specific values in minutes. The ‘0 minutes’ response option was also removed. Summarised figures from 2023 onwards are therefore reported separately for this question, and average queue times are no longer calculated.

Survey weighting

Unless otherwise stated, figures and analysis presented are based on weighted survey records. Further details regarding the methodology employed to apply weighting to the main survey are outlined by the CAA.

Specific weighting coefficients are calculated for this publication by grouping the security screening sub-sample by airport, terminal and destination haul, and dividing the sum of the resulting weighted population by the sample size.

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