Causes and Impact of Extreme Low Level Wind Shear (LLWS) Event at Soekarno-Hatta International Airport

Abstract The impact of low-level wind shear (LLWS) is still a critical issue in aviation. These days, as the aviation industry grows, it must follow safety improvement efforts and transportation management, one of which is through the accurate publishing of LLWS early warning. Therefore, it takes a high understanding related to phenomena, especially at airports with busy schedules. This study examined the causes and impacts of pilot-reported LLWS on April 5, 2018, from 13:15 to 16:00 UTC at Soekarno-Hatta International Airport which is the busiest airport in Indonesia. The data used are Doppler weather radar, automated weather observing system (AWOS), as well as synoptic and upper air observations. Based on the result of this research, linear convective clouds created from deep convection due to very unstable atmospheric circumstances are the cause of LLWS. A sizeable line of convective cloud with a 50-55 dBZ reflectivity accompanied by an outflow microburst (MBA) was detected crashing the airport. Heavy rains and strong winds up to 15-20 m/s speeds from the line of convective cloud triggered the formation of destructive LLWS. Subsequently, there was traffic build-up at 5 flight holding points before landing. Furthermore, 7 flights (Airbus, Boeing, and CRJX) underwent go-around, and 3 flights (Airbus and Boeing) were diverted.