The COVID-19 pandemic disrupted numerous industries. One of the most affected was airline travel as travel restrictions were imposed and borders were closed around the world. These measures affected both domestic and international travel, but it is the movement across borders that experienced the biggest upheaval. In the span of a few weeks at the beginning of 2020, dozens of countries across continents implemented different control measures, including screenings upon arrival; quarantine arrivals from high-risk regions, ban on high-risk regions and total border closure.
These policies disrupted international travel as never before. According to the International Civil Aviation Organization (ICAO), in 2020 there was a drop of 74% in international passengers, from 1.9 billion in 2019 to 500 million in 2020. A similar figure is expected by the end of 2021. Between 2020 and 2021, ICAO estimates, the airline industry will have recorded a loss of around 500 billion USD of gross operating revenues. 
Flight data from OpenSky Network, which contains a record of 848’012’960 flights (origin and destination) between January 1, 2019 and June 30, 2021, shows some disaggregated trends. It is worth mentioning that the database is large, but it presents some important limitations. Data is compiled with open sources (from sensors) and does not contain official information from an aeronautical authority. As a consequence, there is a relatively low number of flights registered in low-income countries –namely there are only 6 low-income countries registered as place of origin: Mozambique, Gambia, Guinea-Bissau, Guinea, Mali, and the Syrian Arab Republic. Of these, Gambia accounts for the 56% of all the air traffic registered in 2020-2021.
Below we describe some trends using as an indicator of mobility the change in the number of flights registered in a given time period, compared to the baseline period. The baseline period is the respective semester in 2019, so that the first semester of 2020 and 2021 are compared to the first six months of 2019 to avoid issues of seasonality. The data shows that all income groups show a decrease in external mobility due to the COVID-19 pandemic: All groups saw a reduction in inbound and outbound flights. However, quantifying with precision the change in mobility for each group may be unreliable due to selection bias in the database, and particularly for low-income countries.
More interestingly, the graph below shows that the decline in inbound and outbound flights for high income countries continued to decrease in the first half of 2021, and in fact the decline was larger than the one observed in 2020.
Similarly, in terms of regions, we note that they all saw a decrease in inbound and outbound flights due to the pandemic, with few exceptions. For example, it is noteworthy that, despite COVID-19, traffic between North American countries (USA and Canada) and Latin American countries recorded significant increases in mobility in the second half of 2020 and the first half of 2021.
Finally, using Sankey diagrams, we observed how the changes in the flight flows of the countries by income group have been due to the pandemic, and found that there have been no relevant ones. When comparing the semesters of 2019 with those of 2020, we observe that the proportion of traffic between countries did not vary significantly. In other words, the decrease in flights affected almost equally all air routes, regardless of whether they are routes between high-income countries and lower middle-income countries, to take one example.
The socioeconomic consequences of the disruption in international air travel have been felt in the tourism sector: according to the UN World Tourism Organization, the decline in international air travel could result in a loss of between USD 910bn-1.2tn in export from tourism from international visitors’ spending. About 100-120 million jobs related to tourism are at risk. These figures should be put in context: in 2020 there were only 14 countries in the world with a GDP larger than USD 1.2tn.