Pilots’ actions after the bird strike are an early focus of the investigation, according to people familiar with the probe.

The investigation into the deadliest air disaster on the country's soil remains ongoing, focusing on the role of bird strike and involving an analysis of the engines and the "localizer" landing guidance structure.

South Korea released a preliminary report into last month’s deadly Jeju Air Co. crash that offers more detail on the role of bird strikes in the disaster, while still leaving crucial questions unanswered.

South Korea has handed in its initial report into the country's deadliest plane crash. Jeju Air flight 2216 exploded last month after an emergency landing. Nearly 180 people were killed, with only two survivors.