In this video, a brief explanation is given to provide the main take-home message from the ROmanian Methane Emissions from Oil and gas (ROMEO) campaign conducted in Romania in 2019. The manuscript utilized airborne in-situ measurements from two aircraft and model outputs from two emission transport simulations. Five inventories were used for executing the simulations and evaluating the datasets. After conducting the analyses, it was concluded that an emission factor (EF) of 5.3 ± 2.0 kg/h/site derived from the evaluations was in good agreement with the EF concluded and previously reported from the ground-based measurements of the ROMEO campaign by Stavropoulou et al. (2023). By comparing the plume areas calculated from the measurements and model outputs, it was evident that the 3.6 kg kg/h/site fixed emission rate assigned for the sites to run the simulation was underestimated. However, quantitative interpretation of the linear regression from the scatter-plot comparison between plume areas from the measurements and model outputs is challenging due to factors such as a few relatively small number of plume areas with large values influencing the linear regression line. The results of this manuscript suggest the previously noted large underreporting of methane emissions from oil and gas activities in Romania in 2019 to UNFCCC and a significant underestimation of methane emissions for the oil and gas industry in EDGAR v7.0 across our study domain.