This paper estimates the impact of the COVID-19 on air travel demand and emissions in Brazil, the largest aviation market in Latin America. Combining detailed flight data and data on combustion emission factors, we estimate the CO2 emissions of domestic flights. A Bayesian structural time-series model was used to estimate the impact of COVID-19 on daily trends of air travel demand and emissions. The COVID-19 caused a reduction of 68% in national passengers and 63% in total CO2 emissions compared to what would have occurred if the pandemic had not happened. Despite such a sharp drop, fuel efficiency decreased after the COVID-19 outbreak, and passenger demand recovered to 64.2% of pre-pandemic levels by the end of 2020. The fast recovery in domestic flights by December 2020 indicates that the emissions could soon return to pre-pandemic levels, demonstrating the challenges of reducing emissions in the aviation sector in the short term.