Authorities have suggested that migratory bird strikes were the cause of last month's deadly plane crash in South Korea, according to multiple reports.

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,

The preliminary report was released by the Aviation and Railway Accident Investigation Board on Monday in South Korea.

Jeju Air Accident Prelim Report Says Ducks Ingested By Both Engines is published in Aviation Daily, an Aviation Week Intelligence Network (AWIN) Market Briefing and is included with your AWIN membership. Already a member of AWIN or subscribe to Aviation Daily through your company? Login with your existing email and password

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

Both engines of the Jeju Air plane that crashed last month contained duck remains, according to a preliminary report.

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The first report on last month’s Jeju Air crash in South Korea confirmed traces of bird strikes in the plane's engines, though officials haven’t determined the cause of the accident that killed all but two of the 181 people on board.