On the day of the accident, the flight crew were scheduled for two round-trip flights between Gimpo and Jeju Airports departing from Gimpo Airport at 11:50. And at the time of the accident, the aircraft was on the final leg to Gimpo Airport after departing from Jeju Airport about 17:05. When flight 8942 was flying along route B5763 to Gimpo Airport after taking off from Jeju Airport, at 17:30:53, the controller instructed flight 8942 to fly heading 040ø for the separation from another aircraft around 30 NM south of NUMNDA, and at 17:32:08, instructed the flight to fly directly to NUMNDA in order to reenter route B576. At 17:33:05, the flight crew requested heading 030ø to avoid clouds during a turn to NUMDA, and the controller gave permission. At 17:34:04, immediately after the flight crew requested the controller for the further descent from an altitude of 16,000 ft, the controller transferred the flight 8942 to Seoul Approach Control, and the Seoul Approach Control controller gave permission to descend to an altitude to 11,000 ft. At 17:36:02, the flight crew requested a high speed descent, and the controller permitted it. In the meantime, the speed of flight 8942 reached up to about 325 knots. At 17:38:33, flight 8942 started to shake as it was passing through an area at an altitude of about 13,000 ft, and the cabin crew announced to check passenger seat belts fastened. At 17:38:42, the captain instructed the first officer to request for a left-turn, and at 17:38:48, the first officer requested the left-turn to the controller (“Seoul Approach, AAR8942 request left Turn”). At 17:39:26, flight 8942 was given permission to turn left to 330ø, and during the turn, it encountered a hailstorm for 36 seconds from 17:40:02 until 17:40:38. After the encounter with the hailstorm, the radome located in the front section of the aircraft was detached, and the surface of windshield was cracked to the extent that there was no forward visibility. In addition, the Auto Thrust System, Auto Pilot System and Flight Director System were disconnected. The flight crew manually attempted to approach and land on runway 14R of Gimpo Airport twice following the radar vectoring of the approach controller, but went around due to its difficulty to make a safe landing. About 18:13, they made a successful landing on the third approach attempt. Findings Related to Probable Causes: The flight route selected by the flight 8942 crew in order to avoid the thunderstorm was not separated enough by distance from the thunderstorm, and the alertness to the thunderstorm paid by the flight crew during descending was not sufficient, and the flight direction chosen when in close proximity to the thunderstorm was not appropriate to avoid the thunderstorm.