National Statistical Institute

Short-term Business Statistics and Transport Statistics Department

National Statistical Institute
2, P. Volov Str.; 1038 Sofia, Bulgaria.

Dataset A1 - Flight Stage dataset : periodic flight stage data registered for airport-to-airport routes, and broken down by arrivals/departures, scheduled/non-scheduled, passenger service/all-freight and mail service, airline information and aircraft type. The values provided concern passengers on board, freight and mail on board, commercial air flights as well as passenger seats available.

Dataset B1 - On Flight Origin/Destination dataset : periodic on flight origin/destination data registered for airport-to-airport routes, and broken down by arrivals/departures, scheduled/non scheduled, passenger service/all-freight and mail service and airline information. The values provided concern passengers carried and freight and mail loaded or unloaded.

Dataset C1 - Airport dataset: periodic airport data registered for declaring airports, and broken down by airline information. The values provided concern total passengers carried, total direct transit passengers, total transfer (indirect transit) passengers (optional variable), total freight and mail loaded or unloaded, total commercial aircraft movements and total aircraft movements.

Data sets A1, B1 and C1 are delivered on a montly basis, while data is provided to EUROSTAT on an quarterly basis.

Airports handling less than 15 000 passenger units annually are not included in the data sets.

Airports are classified according to ICAO (International Civil Aviation Organization) airport coded as listed in ICAO document 7910.

Aircrafts are classified according to aggregated aircraft categories based on the ICAO aircraft codes as listed in ICAO document 8643.

Airlines are classified according to the ICAO airline codes as listed in the ICAO document 8585. When providing the data to Eurostat, the region where they are licensed is coded accordingly either as European Union (EU) or outside the European Union (non-EU).

The information includes data on Bulgarian and foreign air operators, performing flights from and to airports on Bulgarian territory.

The main concepts used in this domain are the following:

Community airport - a defined area on land or water in a Member State subject to the provisions of the treaty, which is intended to be used either wholly or in part for the arrival, departure and surface movement of aircraft and open for commercial air services.

Flight stage - the operation of an aircraft from take-off to its next landing. This is linked to the definition of passengers (or freight and mail) on board.

Passengers on board - all passengers on board of the aircraft upon landing at the reporting airport or at taking off from the reporting airport. All revenue and non-revenue passengers on board an aircraft during a flight stage. Includes direct transit passengers (counted at arrivals and departures).

Direct transit passengers - passengers who, after a short stop, continue their journey on the same aircraft on a flight having the same flight number as the flight on which they arrive.

Transfer of indirect transit passengers - passengers arriving and departing on a different aircraft within 24 hours, or on the same aircraft bearing different flight numbers. They are counted twice: once upon arrival and once on departure.

Freight and mail on board - all freight and mail on board of the aircraft upon landing at the reporting airport or at taking off from the reporting airport. All freight and mail on board an aircraft during a flight stage. Includes direct transit freight and mail (counted at arrivals and departures). Includes express services and diplomatic bags. Excludes passenger baggage.

On flight origin and destination - traffic on a commercial air service identified by a unique flight number subdivided by airport pairs in accordance with point of embarkation and point of disembarkation on that flight. For passengers, freight or mail where the airport of embarkation is not known, the aircraft origin should be deemed to be the point of embarkation; similarly, if the airport of disembarkation is not known, the aircraft destination should be deemed to be the point of disembarkation. This is linked to the definition of passengers carried and freight and mail loaded or unloaded.

Passengers carried - all passengers on a specific flight (with one flight number) counted once only and not repeatedly on each individual stage of that flight. All revenue and non-revenue passengers whose journey begin or terminates at the reporting airport and transfer passengers joining or leaving the flight at the reporting airport. Excludes direct transit passengers.

Freight and mail loaded or unloaded - all freight and mail loaded onto or unloaded from an aircraft. Includes express services and diplomatic bags. Excludes passenger baggage. Excludes direct transit freight and mail.

Passenger unit - one passenger unit is equivalent to either one passenger or 100 kilograms of freight and mail.

The data are collected at individual airport level.

Four categories of Community airports are defined by the Regulation (EC) N°1358/2003:

• Category "0": Airports with less than 15 000 passenger units per year are reported monthly by ICAO Doc 9060 statistical data (Data set I) at national level only.
• Category "1": Airports with between 15 000 and 150 000 passenger units per year are reported monthly by ICAO Doc 9060 statistical data (Data set I) at national level and aggregated airport data ( Data set C)
• Category "2": Airports with more than 150 000 passenger units and less than 1 500 000 passenger units per year shall transmit monthly ICAO Doc 9060 statistical data (data set I) at national level only and  flight stage data, on flight origin destination data as well as aggregated airport data (Data sets A, B and C).
• Category "3": Airports with at least 1 500 000 passenger units per year shall transmit monthly ICAO Doc 9060 statistical data (data set I) at national level only and as well as on flight origin destination data and aggregated airport data (Data sets A, B and C).

Airports under category ‘0’ are not included in the statistics provided to Eurostat.

All commercial airports located at the territory of Bulgaria.

Data has been reported starting from 2007 for flight stage and on flight origin destination data; airport traffic data are available as from 2001.

Not applicable.

The units used depend on the variables collected within each data set and are: number of passengers, tonnes (for freight and mail), aircraft movements and passenger seats available.

According to the legal act the weight of freight and mail is transmitted in tonnes with three decimal places.

Reference period is the calendar year 2022.

National level:

• CIVIL AVIATION ACT, art. 16 
• ORDINANCE No. RD-08-20 OF JANUARY 14, 1999, FOR COLLECTION STATISTICAL INFORMATION ON CIVIL AVIATION  IN THE REPUBLIC OF BULGARIA
• NATIONAL STATISTICAL PROGRAMME

European level: until 2002, the data were provided to Eurostat on a voluntary basis; since 2002 data provision is based on an EP and Council framework legal act and on several implementing Commission Regulations:

• 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.
• Commission Regulation (EC) No 1358/2003 of 31/07/2003.
• Commission Regulation No 546/2005 of 8 April 2005.
• Commission Regulation No 158/2007 of 16 February 2007.

Not applicable.

National level:

• law on Statistics Art. VI

European level:

• 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.

The data provided to Eurostat in the data sets A1, B1 and C1 contain no confidential information.

The procedures with regard to statistical confidentiality folllows the Handbook on Statistical Disclosure Control (2010) and the Law on Statistics.

The data provided to Eurostat in the data sets A1, B1 and C1 contain no confidential information.

Data confidentiality problems: Since in statistical forms there is a direct identification of the statistical subject, they are subject to protection pursuant to the Information Classification Low with classification level "For official use". This protection has been also specified by an Order of the Director General of DG CAA. Access to the forms is allowed only to persons holding a special clearance for the same or higher classification level. These restrictions are valid for two years. Summarized references may be made during this period, given that subject identification is impossible. 

Deractorate General "Civil Aviation ѝdministration":

International and domestic passengers, freigfh and mail traffic at airports in Bulgaria (monthly and annual)

Place of publication: on website   - https://www.caa.bg/bg/category/292

Date of publication: 27.09.2023

National statistical Institute: Data are published according to the deadlines set in the National statistical programme and the release calendar- six months after the reference period.

The calendar is available on the NSI website: http://www.nsi.bg/en/node/480

Data are published on the internet site of NSI and DG CAA and can be accessed from all users of statistical information.

Aggregated data set  A1 are annualy published on NSI website.

International and domestic passengers, freight and mail traffic at airports in Bulgaria (montly and annual) and aggregated annual data for the Bulgarian aviation operators are annually published in website of the DG CAA.

Not applicable.

Statistical yearbook.

Data on Air transport are avaiblle on the NSI website https://www.nsi.bg/en/content/7158/air-transport

Not applicable to air transport statistics.

Not applicable.

Referance Manual on Air Transport Statistics

Referance manual on Air Transport Statistics

National guide for Air Transport is developed to facilitate the process. It contains the regulatory framework, the reported statistical forms and methodological guidelines for all data series. The National guide includes also functionalities for the IT sector, form and structure of the data from A1, B1, C1 as well as the paths for quality control when the data has been transferred from the primary source into the database and the conduction of the statistical forms.

Annualy Eurostat prepares a data quality report with the summary of the main findings affecting the quality of the data. Mirror checks do not  indicate  problems with the date from Bulgaria. On request by Eurostat , Bulgaria have been commented on individual records or statistics information.  

Main users are state instituitions, different organizations and specialised in the sector enterprises.

Not applicable.

Full completeness with the Bulgarian and Europian legislation.

Overall accuracy of the air transport statistics data is very good. This is due to the overall methodology for processing the primary documents for each flight.

Not applicable for air transport data collection.

Not applicable.

All the statistics required by the provisions of the Regulation 437/2003 are transmitted to Eurostat 4 months after the reference quarter.

Difficulties to respect deadline for data transmission: In principle, the deadline for airports submitting the statistical forms to DG CAA is Т+15 days (pursuant to Regulation РД-08-20). For Bulgaria there would not be any difficulties in submitting the forms every Т+5 months.

All the statistics required by the provisions of the Regulation 437/2003 are available 2 months before the deadline for the data provisions set up in the legal act.

There are no problems of comparability for air transport data collection with a high data comparability across countries due to the common legal basis.

Comparability over time is accomplished due to present metodological approach, which has been implemented over the past years.

Not applicable.

At national level, inter-dataset checks for each data series are made.

Cost and Burden are defined from Directorate general "Civil Aviation administration" at the Ministry of transport, informatin technology and communications. Information on statistical datasets is extracted from aairport database using a common metodology.

Data revision is made when it is necessary.

Data revission is made by necessity according to the metodology.

Dataset A1 – Data Suppliers (Passengers on board/Freight and mail on board):

Passengers on board: 

1. DG CAA provides the information to the National Statistical Institute. DG CAA is a statistical authority within the meaning of art. 3, par. 2 of the Statistical Law. NSI of Bulgaria will check the data and will supply the statistical information to Eurostat.
2. DG CAA receives information from the airports (Regulation РД 08-20 of 14 Jan 1999 on collecting statistical information for civil aviation in the Republic of Bulgaria)
3. Airports generate information from the official documents for scheduling and carrying out each flight. 

Freight and mail on board : Same. Separately, bigger specialized companies, which are also, ground service operators (DHL, M&M, etc.) provide airports with information about cargo and mail being loaded or unloaded by them. This information is being used when necessary.

Aircraft Information in A1: Loadsheet.

Seats information information in A1: Loadsheet, it states the configuration of the specific aircraft.

Dataset B1 –Data Suppliers (Passengers carried/Freight and mail loaded/unloaded)

Passengers on board: 

1. DG CAA provides the information to the National Statistical Institute. DG CAA is a statistical authority within the meaning of art. 3, par. 2 of the Statistical Law. NSI of Bulgaria will check the data and will supply the statistical information to Eurostat.
2. DG CAA receives information from the airports (Regulation РД 08-20 of 14 Jan 1999 on collecting statistical information for civil aviation in the Republic of Bulgaria)
3. Airports generate information from the official documents for scheduling and carrying out each flight. 

Freight and mail on board: Same. Separately, bigger specialized companies, which are also, ground service operators (DHL, M&M, etc.) provide airports with information about cargo and mail being loaded or unloaded by them. This information is being used when necessary.

Datasets A1 and B1 - Use of Air Waybill Data as information source of freight data: Used by exception when necessary. The air-cargo agent prepares the air waybill. Air cargo agent takes the decision whether to perform transportation by air or by truck. The airport administration receives information only about the cargo which will actually be loaded onboard (or unloaded) and which information is included in the loadsheet. Cargo transported by truck is not included in the provided information.

Dataset C1 – Bodies that supply the direct transit information to the CNA:

Passengers on board:

1. DG CAA provides the information to the National Statistical Institute. DG CAA is a statistical authority within the meaning of art. 3, par. 2 of the Statistical Law. NSI of Bulgaria will check the data and will supply the statistical information to Eurostat.
2. DG CAA receives information from the airports (Regulation РД 08-20 of 14 Jan 1999 on collecting statistical information for civil aviation in the Republic of Bulgaria)
3. Airports generate information from the official documents for scheduling and carrying out each flight.

Freight & mail on board: Same. Separately, bigger specialized companies, which are also, ground service operators (DHL, M&M, etc.) provide airports with information about cargo and mail being loaded or unloaded by them. This information is being used when necessary.

The main source is the loadsheet. Standards electronic IATA messages (IATA messages) are being used in isolated cases to obtain information or to perform a check.

Commercial and total aircraft movements: See the point just above.

The airports provide information to DG CAA (Dataset A1,B1,C1) monthly on an external CD or through encrypted password protected files.

Dataset A1 – Data supplier’s information sources (Passengers on board/ Freight and mail on board): The main source is the loadsheet. Standards electronic IATA messages (IATA messages) are being used in isolated cases to obtain information or to perform a check.

Dataset A1 – Data transmission to CNA – level of aggregation, system and periodicity (Passengers on board/ Freight and mail on board):

1. Every day airports enter the loadsheets for each flight into a common information database.
2. The statistical forms А1, В1 and С1 are monthly excerpts from the common database made by to a special algorithm.
3. Information is being passed on magnetic media or through coded email (password-protected ZIP file).

Dataset B1 – Data supplier’s information sources (Passengers carried/ Freight and mail loaded/unloaded): The main source is the loadsheet. Standards electronic IATA messages (IATA messages) are being used in isolated cases to obtain information or to perform a check.

Dataset B1 – Data transmission to CNA – level of aggregation, system and periodicity(Passengers carried/ Freight and mail loaded/unloaded):

1. Every day airports enter the loadsheets for each flight into a common information database.
2. The statistical forms А1, В1 and С1 are monthly excerpts from the common database made by to a special algorithm.
3. Information is being passed on magnetic media or through coded email (password-protected ZIP file).

Datasets A1 and B1 - OFOD data derived from FS data or collected separately by the data supplier: Due to the flight number condition, OFOD data are being extracted from the common database, i.e. from the loadsheets for each flight.

Implementation of the data collection and compilation process: To obtain the statistical forms, Sofia Airport uses the existing database. Only the ICAO codes of airlines and airports were additionally entered. Providing the information for the Regulation 437 on statistical returns in respect of the carriage of passengers, freight and mail by air statistical forms was one of the arguments for developing and implementing new information systems for entering and processing flight information at Varna, Burgas and Plovdiv airports.

Data validation procedure :

NSI of Bulgaria  use SDMX format for data validation procedure. All inter data set checks are performed at national level before data transmission.

Description of consistency checks :

• validation of coding with ICAO lists (airports, airlines, airplanes),
• comparing the number of passengers with the amount of space offered on the plane,
• checking the number of passengers per flight (only in the set A1 and C1),
• checking the amount of cargo per flight (only in the set A1 and C1, with the comparison of loads is a big problem, because there is no combination of the type of aircraft with the ICAO code and the possible maximum transport of cargo).

After various plausibility checks, the data received from the airports are compiled into monthly data following the structure of the data sets which are preset by regulation (EC) 1358/2003.

Data codification practices: ICAO codes are being used. When entering IATA codes used in the loadsheet, the program automatically generates in a separate field the respective ICAO code. Since the dynamics of registering airlines with ICAO is greater than the regularity of issuing Document 8585, when necessary and by request of the airports, DG CAA makes orderly references directly with ICAO.

Problems on data compilation, validation and delivery: No problems encountered.

Not applicable for air transport data collection.

Not applicable.