Guidance

Aviation: notes and definitions

Updated 14 December 2023

About this release

These notes and definitions accompany the statistical release Transport Statistics Great Britain, 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 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 are based on the data collected from the CAA Departing Passenger Survey
• table AVI0401 is compiled from data supplied by the CAA’s Safety Data Unit
• table AVI0301 is based on data supplied by the International Civil Aviation Organisation (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.

Airports in the Channel Islands are excluded from AVI01 series data tables. Isle of Man Airport is included in table AVI0101 until 1991, 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 2000, 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 2000 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 country of embarkation or landing.

Prior to the 2017 publication year, table AVI0105 was derived from the CAA Airport Statistics, Table 12.1. This table made the following exclusions:

• several small airports, which do not submit full returns to the CAA

• charter aircraft with fewer than 25 seats

• airlines that have not given consent to the CAA to publish their data

• passengers carried on aircraft chartered by government departments

The figures in the table are based on the origin and destination of passengers as reported to UK airport authorities by UK and foreign airlines. Operators are required to report in respect of each service operated, the point of uplift and discharge of each passenger. The figures may not reflect a passenger’s entire air journey as the point at which a passenger disembarks from a particular service may not represent the ultimate destination.

From the 2017 publication year, the figures in this table are derived from the version of the CAA Airport Statistics held by DfT. The number of international passengers reported in Table AVI0105 are consistent with those reported in Table AVI0102. Countries of embarkation or landing 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.

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, 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 are given for the 5 UK airports which have been included in the survey every year since 2000: Heathrow, Gatwick, Stansted, Luton and Manchester. In more recent years, a small number of additional airports are also 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 passenger, 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 Organisation (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.

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