What happened
On March 20, 2024, at approximately 16:15 JST, an All Nippon Airways Boeing 787-9, registration JA891A, was struck by lightning while descending toward Narita International Airport. The aircraft, which had originated from Los Angeles International Airport with 207 people on board, was flying at an altitude of roughly 1,500 meters, approximately 77 km east-southeast of the airport.
Prior to the event, the flight crew had monitored weather radar and ACARS updates, noting moderate echoes to the south and southwest of the airport. While the crew implemented heading changes to avoid identified echo areas, the aircraft was suddenly struck by lightning. Following the strike, the crew noted a brief burning smell and a warning message regarding the left weather radar system, though other instruments remained functional. The aircraft landed safely at Narita at 16:29 with no injuries reported among the 195 passengers and 12 crew members.
The investigation
The Japan Transport Safety Board (JTSB) examined the aircraft's flight records, meteorological data, and the physical state of the airframe. The investigation focused on the extent of the damage to the composite structure and the meteorological conditions at the time of the strike. Investigators analyzed thunder nowcasts from the Japan Meteorological Agency and reviewed the flight crew's use of onboard weather radar and company-provided weather applications. The investigation also looked into the specific properties of the aircraft's carbon fiber reinforced plastic (CFRP) fuselage skin and how it responded to the electrical discharge.
Findings
Post-landing inspections revealed substantial damage to the aircraft. The lightning strike caused delamination of the outer skin on the forward right side of the fuselage, a condition requiring major repairs because the separation had propagated through all layers of the composite material. Additionally, several burn marks were identified on the radome and the upper and rear sections of the fuselage.
Meteorological analysis indicated that while active cumulonimbus clouds were located further away near the Boso Peninsula, the lightning activity in the immediate vicinity of the aircraft was rapidly increasing between 15:30 and 16:10. The aircraft was flying at an altitude where the temperature was -2°C, a zone identified as having a high risk for electric discharge. The JTSB concluded that the rapidly increasing probability of a lightning strike made it highly difficult for the crew to predict or avoid the event despite their active monitoring of weather patterns.