Incident Overview
On 17 November 2023 at 8:25 p.m., a Boeing 737-800 aircraft, registration HS-DBT, operated by Nok Airlines Public Company Limited as flight DD578, was cruising at flight level 340 (FL340) en route from Don Mueang International Airport to Surat Thani International Airport. During the flight, the pilots requested an emergency descent to 10,000 feet and used the oxygen masks. The aircraft subsequently landed at Don Mueang International Airport without damage. There were no injuries or fatalities.
Classification and Response
The event was classified as a serious incident under the category "Events requiring the emergency use of oxygen by the flight crew." The Aircraft Accident Investigation Committee for the Aircraft Accident and Incident Investigation Commission Thailand notified the National Transportation Safety Board of the United States (NTSB) as the State of Aircraft Design and Manufacture, as well as the International Civil Aviation Organization (ICAO).
Investigation Status
As of the interim report dated September 2025, the investigation was in the process of finalizing a draft final report. The committee stated that the final report would be published along with the cause of the serious incident. Additionally, the committee plans to recommend preventive measures to domestic and international aviation authorities. If any circumstances requiring immediate action were discovered during the investigation, necessary measures would be taken to ensure flight safety.