Accident Overview
On 11 December 2023 at 08:23 local time, a U.S. Air Force F-16CM (tail number 88-0479) assigned to the 80th Fighter Generation Squadron, 8th Fighter Wing, Kunsan Air Base, Republic of Korea, departed for a local defensive counter air training mission. The mishap pilot (MP), assigned to the 35th Fighter Squadron, was flying as number three in a four-ship formation. At approximately 08:42 local time, while transiting through the training airspace, the MP ejected from the aircraft. He was uninjured. The aircraft impacted the water approximately 81 nautical miles west of Kunsan Air Base in the Yellow Sea and was destroyed, resulting in a loss of $28,259,045.
Flight Events
The mission was planned and authorized as a defensive counter air training flight. Observed weather in the training areas was worse than forecasted, with dense cloud coverage throughout. At approximately 08:37 local time, while in instrument meteorological conditions (IMC) inside clouds, the MP lost the primary attitude indicator, which relied on an embedded global positioning system inertial navigation system (EGI) that had failed. The MP then used the standby attitude indicator (SAi), which earlier in the flight had displayed slight pitch and bank errors, increasing difficulty in maintaining orientation. With assistance from a wingman providing navigation and altitude information, the MP began a descent toward expected clear skies. While still in IMC at 3,000 feet mean sea level, the MP attempted to level off but became further disoriented. Losing confidence in the aircraft's attitude near the water, the MP decided to eject.
Investigation Findings
The accident investigation board found, by a preponderance of evidence, that the cause of the mishap was an EGI failure while in IMC. The malfunctioning EGI led to a loss of primary flight and navigation instruments. The board also found that the subsequent reliance of the MP on the standby attitude indicator, which had previously displayed abnormal indications, and the spatial disorientation of the MP, substantially contributed to the mishap. The crash survivable memory unit (black box) was not available at the time of the report.