Motivation The data in this dataset is derived and cleaned from the full OpenSky dataset to illustrate the development of air traffic during the COVID-19 pandemic. It spans all flights seen by the network's more than 2500 members since 1 January 2019. More data will be periodically included in the dataset until the end of the COVID-19 pandemic. License See LICENSE.txt Disclaimer The data provided in the files is provided as is. Despite our best efforts at filtering out potential issues, some information could be erroneous. Origin and destination airports are computed online based on the ADS-B trajectories on approach/takeoff: no crosschecking with external sources of data has been conducted. Fields origin or destination are empty when no airport could be found. Aircraft information come from the OpenSky aircraft database. Fields typecode and registration are empty when the aircraft is not present in the database. Description of the dataset One file per month is provided as a csv file with the following features: callsign: the identifier of the flight displayed on ATC screens (usually the first three letters are reserved for an airline: AFR for Air France, DLH for Lufthansa, etc.) number: the commercial number of the flight, when available (the matching with the callsign comes from public open API) icao24: the transponder unique identification number; registration: the aircraft tail number (when available); typecode: the aircraft model type (when available); origin: a four letter code for the origin airport of the flight (when available); destination: a four letter code for the destination airport of the flight (when available); firstseen: the UTC timestamp of the first message received by the OpenSky Network; lastseen: the UTC timestamp of the last message received by the OpenSky Network; day: the UTC day of the last message received by the OpenSky Network; latitude_1, longitude_1, altitude_1: the first detected position of the aircraft; latitude_2, longitude_2, altitude_2: the last detected position of the aircraft. Examples Possible visualisations and a more detailed description of the data are available at the following page: <https://traffic-viz.github.io/scenarios/covid19.html> Credit If you use this dataset, please cite: Martin Strohmeier, Xavier Olive, Jannis Lübbe, Matthias Schäfer, and Vincent Lenders "Crowdsourced air traffic data from the OpenSky Network 2019–2020" Earth System Science Data 13(2), 2021 https://doi.org/10.5194/essd-13-357-2021