On 9 June 2006, an Airbus 321-100, operated by Asiana Airlines, encountered a thunderstorm accompanied by Hail around 20 miles southeast of Anyang VOR at an altitude of 11,500 ft, while descending for an approach to Gimpo Airport. The radome was detached and the cockpit windshield was cracked due to impact with Hail.
This is an extract from the Executive Summary of the official report into the accident published by the Korean ARAIB:
"On June 9, 2006, about 17:40, Asiana flight 8942 (flight 8942 hereinafter), an Airbus 321-100 (Registration HL7594), operated by Asiana Airlines, en route from Jeju International Airport (Jeju Airport hereinafter) to Gimpo International Airport (Gimpo Airport hereinafter), encountered a thunderstorm accompanied by hailstones around 20 miles southeast of Anyang VOR at an altitude of 11,500 ft during descending to approach Gimpo Airport, and the radome in the nose section of the aircraft was detached and the cockpit windshield was cracked due to impact with ice stone carried by the thunderstorm… no one sustained injuries in this accident…
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.
Findings Related to Risk:
- Flight 8942 was maintaining high descending speed when encountered with the thunderstorm.
- The speed of flight 8942 was increased to 346.4 kts almost close to the maximum operating speed (350 kts) after disconnection of auto thrust and auto pilot systems.
- The noise generated after the detachment of the radome seriously hindered conversations between the flight crew and the communications between the flight crew and the approach control.
- The cracked cockpit windshield seriously impeded the flight crew from having visual contact with the runway and making a landing.
- The disconnection of auto thrust, auto pilot and fight director systems seriously impeded the flight crew from making a stable landing.
- Asiana Airlines did not use the weather forecast or SIGMET information officially dispatched by Aviation Meteorological Office through AFTN by means of having them input in the FMC, instead obtained the necessary weather information including weather forecast by means of logging into the weather information system provided additionally by Aviation Meteorological Office.
- SIGMET information was not announced by Aviation Meteorological Office although it existed between 16:30 and 18:30 on the day of accident.
- It is stipulated in a relevant agreement that the weather forecaster of Aviation Meteorological Office should conduct a weather briefing to the Air Traffic Center controllers, however, on the day of accident, the briefing was not conducted to the group of the controllers on duty who provided the ATC services to flight 8942.
- The controllers of Seoul Approach Control could not receive directly in their control seats SIGMET information officially provided by Aviation Meteorological Office, instead, they used a system of obtaining weather information by logging into the weather information system provided additionally by Aviation Meteorological Office, which was insufficient to receive on time the weather forecast or SIGMET information announced at irregular hours.
- Under the weather condition of visibility of 5 miles or less in Gimpo Airport, the airport lightings were switched on by the Gimpo Tower controller 14 minutes after the controller was aware of the emergency landing declared by flight 8942, the timing of which was inappropriate.
- Air traffic control and Seoul approach control were not operating the broadcasting system on the SIGMET information for the aircraft flying in their control areas…"
Damaged Windshield Installed in Aircraft
- For further information see the full Accident Report published by the Aviation and Railway Accident Investigation Board of South Korea.