Overview
The Airport Local Air Quality Studies tool (Open-ALAQS) was developed in the context of SESAR to allow its providers to perform local air quality assessments. The tool can be used also for forecasting air quality (e.g., following changes in infrastructure and/or traffic, use of SAF etc.) and for action planning.
The current version is called Open-ALAQS v4, the last major update was provided in January 2025. The source code is, for the first time, publicly available on GitHub under the European Union Public Licence v.1.2.
The key difference with other EUROCONTROL tools is that Open-ALAQS is not limited to aircraft emissions but can calculate emissions from various airport (non-aircraft related) sources including road traffic emissions.
Open-ALAQS can calculate and visualise or export emissions for each of the available source types. The user can just select one emission source or have the whole picture by selecting all sources at the airport at the same time. Sources can be chosen also by name, so the software offers great flexibility in modeling emissions based on their needs.
There are two methods for calculation:
- By ICAO mode which is covering the whole LTO cycle (all 4 different phases within the LTO cycle).
- BFFM2 – more advanced method.
For those who are familiar with dispersion modeling it is useful to mention that Open-ALAQS also allows to set receptor points or so-called “points of interest”. Defining those points allows the user to flag significant points, such as a school, a hospital, etc.
An important element that is included in the calculation is meteorological data (e.g., METAR, SYNOP). If precise methodological information is not available, standard atmospheric conditions (ISA) are applied.
Open-ALAQS supports service providers in their environmental efforts as follows:
- Emission Estimation: Open-ALAQS estimates emissions from various airport sources, including aircraft operations and on-airport infrastructure like landside and airside road traffic. This helps the service providers understand the sources and levels of pollutants.
- Comprehensive Modelling: The tool performs a four-dimensional inventory of emissions, calculating and aggregating emissions from both airport and non-airport sources. This comprehensive approach allows for detailed analysis and better management of air quality.
- Dispersion Modelling: Open-ALAQS is coupled with AUSTAL, a dispersion model to calculate pollutant concentrations at and around airports over time. This helps assessing the impact of their operations on local air quality and identify areas for improvement.
- Regulatory Compliance: The tool is compatible with European legislative requirements for pollutant concentrations, helping service providers ensure they meet environmental standards.
Provider
EUROCONTROL
Versions and OS Requirements
Open-ALAQS is developed as a plugin for the open-source geographic information system QGIS. It is fully based on an open architecture, making it easily adaptable to other GIS platforms and databases.
The current version of Open-ALAQS is a cross-a- platform tool, which means it can be used on Windows, Linux, or MacOS.
Data Requirements
The following databases are used in Open-ALAQS:
- ICAO Engine Emissions Database for jet engines Emission Factors (EFs).
- FOCA Piston engine EFs.
- Possible to use turboprops EFs from the FOI database.
- ANP Database for performance profiles.
To create a new study, it is necessary to provide some general information starting from the name of the project, basic information about the airport (at least ICAO code), the average fleet year and the country, to assign/use the country-specific emission factors.
The next step is to design the emission sources for the chosen airport like taxiways, runways etc. The software supports the use of different base maps which allows the user to create a very precise and detailed picture of the airport. An additional functionality is added to Open-ALAQS to facilitate the creation of emission sources based on the geographic data (roads, buildings, points of interest and more) provided by OpenStreetMap.
The user can also create road traffic emission sources (airside or landside), including parking spaces. Using COPERT V, Open ALAQS can estimate the custom emission factors for those sources based on user defined activity data, like the number of vehicles used or the composition of the fleet. The emission factors are then calculated for the given configuration and for each specific roadway segment in the study, which makes it more accurate and offers higher flexibility.
Limitations
Currently, there is no possibility of considering real aircraft trajectories (e.g., ADS-B). Aircraft emissions are based on fixed-point profiles from the Aircraft Noise and Performance (ANP) database which contains a standardised dataset with information related to aircraft flight performance under various conditions.
Future Developments
Open-ALAQS remains independent of the dispersion model and other similar modules can be added in the future. A new module is under development that will allow the handing of real aircraft trajectories from ADS-B data, including ground (taxiing) tracks for higher accuracy.