## 1 Introduction  
Terminal area, as a key node in the air transport network, is a complex area which provides air traffic control service for arrival and departure aircrafts. It usually contains one or more airports characterized by dense and changeable traffic flow, intricate route structure and multiple coexistence of runway operation modes. Due to the unreasonable route network planning in the terminal area, the air emissions and noise from aircraft seriously affect the ecological environment, and the contradiction between the development of civil aviation and environmental protection is increasingly prominent. Therefore, on the premise of ensuring safety, reducing the environmental impact of air traffic in the terminal area is of great significance to promote the development of green civil aviation and sustainable social development [1]. In general, flight activity is an important source of air and noise pollutants. Areas close to airports are usually more polluted [2; 3]. With regard to it, many scholars have studied the route optimization of emission and noise reduction in terminal area air route network and achieved a series of achievements. Regarding the optimization of emission reduction and noise reduction for a single route in the terminal area, [PERSON] analyzed the data of the descending trajectory of some aircraft types, and calculated the optimal position of the top of descent (TOD) with the given thrust and drag models, by considering the environmental impact [4]. [PERSON] selected the optimal flight speed of aircraft along the departure route by taking noise and fuel consumption into consideration [5]. [PERSON] et al. designed a de-noising optimization method for departure route based on fuzzy theory [6]. [PERSON] et al. took the arrival route of Seattle Airport as an example for analysis, and the results showed that the optimized single arrival route could save about 40% of fuel consumption at most [7]. [PERSON] et al. proposed the design method of emission reduction and noise reduction of departure route in terminal area under the influence of single event, combining with the degree of residents' annoyance caused by noise [8]. [PERSON] et al. proposed a noise-reducing trajectory design method for arrival routes with the influence of multiple events, and designed a piecewise optimization method for approach routes based on Area Navigation (RNAV) [9]. [PERSON] et al. considered aircraft conflicts in the terminal area and proposed the arrival route design method based on the light propagation model by referring to the mode of light propagation in media [10; 11]. [PERSON] et al. used two-layer hybrid algorithm to calculate the minimum noise trajectory [12]. [PERSON] et al. designed an improvement method of the arrival route for preliminary noise reduction, by taking the population affected by noise as the evaluation reference, and changed the noise impact range by changing the horizontal flight path of aircraft [13; 14]. [PERSON] et al. used the atmospheric dispersion model to construct the dispersion model of air emissions in the terminal area, and the emission databank of International Civil Aviation Organization (ICAO) was utilized to estimate the pollutant emission rate of each aircraft [15]. On the route network path optimization of the terminal area, [PERSON] et al. optimized the two-dimensional route network path of the terminal area. The results showed that the optimized arrival and departure route could effectively reduce fuel consumption [16]. In order to further reduce the mutual interference between routes, [PERSON] et al. studied the take-off and landing route of runway 05L of Xianyang Airport in Xi 'an [17; 18], proposed 3D departure route optimization method with the shortest path and the route network optimization sequence principle. [PERSON] et al. designed the route trajectory search method with angle extension and proposed the economic optimal method to arrival and departure route optimization [19]. [PERSON] et al.