Research on the Impact of Airport Emergencies on Aircraft Pollutant Emissions

Airport emergency events can significantly disturb normal flight operations and lead to temporary flight control measures, which may further affect aircraft pollutant emissions and the surrounding air quality of airports. As an important source of air pollutants during airport operations, aircraft emissions are closely associated with flight activity levels, operational procedures, and aircraft movement characteristics. Under normal operating conditions, aircraft emission characteristics are relatively stable; however, emergency events may cause temporary changes in aircraft operation patterns, resulting in variations in pollutant emission levels and spatial distribution characteristics. With the continuous growth of air transportation activities, aircraft emissions during airport operations have attracted increasing attention due to their potential influence on local atmospheric environments. Therefore, evaluating emission changes under emergency scenarios is necessary for improving the understanding of airport environmental impacts.

Although aircraft emission inventories have been widely applied to evaluate the environmental impacts of airport operations, most studies focus on normal operational scenarios, while the emission characteristics under temporary flight control conditions remain insufficiently investigated. In particular, the influence of temporary flight control on aircraft pollutant emission levels and spatial distribution characteristics before, during, and after emergency events requires further analysis. Therefore, this study investigates the influence of temporary flight control caused by airport emergency events on aircraft pollutant emissions. The changes in total emissions and temporal-spatial distribution characteristics of aircraft pollutants during different operational periods are analyzed to provide a basis for airport environmental impact assessment and emergency management.

Tianjin Binhai International Airport was selected as the study area. Based on actual flight trajectory data, a hybrid machine learning model was applied to characterize aircraft fuel consumption during take-off and landing operations. The model was used to establish the relationship between flight trajectory characteristics and fuel flow, providing the basis for estimating aircraft fuel consumption under actual operating conditions. The estimated fuel consumption was combined with the standard emission database provided by the International Civil Aviation Organization (ICAO) to calculate aircraft pollutant emissions. A high-resolution dynamic emission inventory was constructed for the temporary flight control period and the periods before and after the emergency event. The study period was divided into three stages: the period before the event (C1), the temporary flight control period (C2), and the period after the event (C3). The emission characteristics of aircraft pollutants during different periods were compared to evaluate the influence of temporary flight control. Based on the constructed dynamic emission inventory, the temporal-spatial distribution characteristics of major aircraft pollutants were analyzed. The horizontal distribution characteristics were evaluated according to different airport functional areas, including runway areas, taxiways, and aprons. The vertical distribution characteristics were analyzed according to different altitude ranges, including the middle and high altitude region above 500 m and the near-ground region from 0 to 500 m. The constructed emission inventory provides a detailed description of aircraft pollutant emissions under different operational conditions and allows comparison of emission variations among different stages of emergency events. This approach enables the identification of emission changes caused by temporary flight control and supports quantitative evaluation of airport emergency impacts.

The results show that temporary flight control significantly affected aircraft pollutant emissions in the airport area. During the temporary flight control period (C2), the daily average emissions of major aircraft pollutants decreased by 23.1% and 27.4% compared with the period before the event (C1) and the period after the event (C3), respectively. The reduction in total emissions was mainly related to the decrease in aircraft operating activities caused by temporary flight control. In addition to changes in total emission levels, temporary flight control also significantly changed the temporal-spatial distribution characteristics of aircraft pollutants. From the perspective of horizontal distribution, pollutant emissions decreased in runway areas but increased in taxiway and apron areas during C2. The daily average NOx emission in runway areas was 22.9 g·d⁻¹, which decreased by 20.2% compared with C1. In contrast, the daily average emissions of CO and HC in taxiway and apron areas were 11.24 g·d⁻¹ and 0.87 g·d⁻¹, respectively, representing increases of 21.7% and 18.1% compared with C1. The changes in different airport functional areas were mainly associated with variations in aircraft operation processes during temporary flight control. The reduction of flight activities resulted in decreased emissions in areas related to aircraft take-off and landing operations, while changes in ground operation conditions contributed to increased emissions in taxiway and apron areas. The vertical distribution characteristics of pollutant emissions also changed significantly during the temporary flight control period. The daily average emissions of pollutants increased in the middle and high altitude region above 500 m but decreased in the near-ground region from 0 to 500 m. Compared with C1, the proportion of NO_x emissions in the middle and high altitude region increased by 20.2% during C2. Meanwhile, the proportions of HC and CO emissions in the near-ground region decreased by 27.2% and 28.3%, respectively. These results indicate that temporary flight control not only affects the total amount of aircraft pollutant emissions but also changes the spatial distribution characteristics of pollutants at different airport areas and altitude levels.

The results demonstrate that airport emergency events have significant impacts on aircraft pollutant emissions and their spatial distribution characteristics. Temporary flight control caused by emergency events changes aircraft operating conditions, resulting in variations in both total pollutant emissions and their distribution patterns in horizontal and vertical dimensions. The assessment of aircraft pollutant emissions under emergency scenarios should consider the changes caused by temporary flight control. Systematic analysis of the influence of temporary flight control on aircraft operating pollutant emissions can provide support for airport emergency response and effective emission control. The dynamic emission assessment method applied in this study can provide a reference for evaluating the environmental impacts of airport emergency events. The findings also emphasize the necessity of incorporating temporary operational changes into airport emission assessments.