中国澳门国际机场重着陆事件的天气背景分析

对2018年8月28日北京首都航空公司CBJ5759航班在中国澳门国际机场发生重着陆事件分析结果,显示:(1)机场位于低空切变线南侧,低空西南急流与海陆地形辐合作用下形成的暖区局地对流引发分散性短时强降水和弱雷暴;对流北侧突然增强的偏南风使机场跑道附近顺风增加,引发低空风切变;(2)高分辨率数值模拟结果表明低空风切变发生时段内存在西南急流脉动,急流北侧的风场由西南风转为偏南风,促使海陆边界的热力和动力不稳定条件加强,有利于局地对流系统发展和其辐散出流增强,加速边界层内风场变化;(3)当飞机在下降过程中经过对流系统前侧激发的偏南风急流区时,水平风的垂直切变形成的顺风切变大于垂直风变化,增加的顺风使飞机空速减小,导致飞机升力减小并造成重着陆;(4)此次事件中天气系统的变化通过影响对流的发展间接促进低空风切变的发生,因此可在对沿海机场的低空风临近预报时通过加强对海上风场变化的监测来预估一定风险。

Weather background analysis of heavy landing event at Macau International Airport

On August 28, 2018, Beijing Capital Airlines flight CBJ5759 suffered a hard landing at Macau International Airport. According to the investigation results of Civil Aviation Authority,meteorological conditions in the approach area of Macao International Airport changed significantly when the incident occurred. The unstable airflow at the boundary layer caused severe low-level wind shear, which caused the aircraft to hard landed and damaged. Results show that:(1) the airport was located on the south side of low-altitude shear line,and the local warm convection formed by low-altitude southwestern jet and land-sea convergence caused scattered short-term heavy precipitation and weak thunderstorms. The rapidly increasing southerly wind on the north side of convection increased the tailwind near airport runway, triggered low-level wind shear. (2) High-resolution numerical simulation results showed that there were pulsations of southwest jets during the period of low-level wind shear. The wind direction on the north side of jet had changed from southwest to southerly, which promoted the strengthening of thermal and dynamic unstable conditions at the land-sea boundary. This was conducive to the development of local convective system and the enhancement of its divergent outflow, accelerating the wind changes in boundary layer. (3) When aircraft passed the southerly jet region excited by thermal convection front during the descent, the tailwind shear formed by by the vertical shear of horizontal wind was greater than the vertical wind change. The increasing tail wind reduced the airspeed of aircraft, resulted in a reduction in aircraft lift and a heavy landing.(4) The changes of weather system in this incident indirectly promoted the occurrence of low-level wind shear by affecting the development of convection. Therefore, certain risks can be estimated by strengthening the monitoring of wind changes on the sea when forecasting low-altitude wind at coastal airports.