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’s authorities investigating last month’s Jeju Air plane crash have submitted a preliminary accident report to the UN aviation agency and to the authorities of the United States, France and Thailand,

South Korean authorities have submitted a preliminary report on last month's fatal Jeju Air crash to the International Civil Aviation Organization. The ongoing investigation focuses on a 'bird impact' as well as examining the aircraft's engines and landing systems.

South Korea released on Monday a preliminary report on its investigation into a Jeju Air crash on Dec. 29 at Muan International Airport that killed 179 people in the deadliest air disaster on the country's soil.

The transport ministry instructed nine low-cost carriers to improve safety standards and avoid prioritising cost-cutting.