[4][1] The 777-312ER encountered severe turbulence at around 07:49 UTC on 21 May 2024 (14:19 local time)[3] over Irrawaddy Basin in Myanmar, around 360 nautical miles (667 km; 414 mi) from Bangkok.

[15][16] Fifteen Britons,[12] twelve Australians,[17] nine Malaysians,[14] five Filipinos,[18] four New Zealanders, two Singaporeans, and one Hong Konger were also injured.

[20] Most victims were treated for fractures including to the vertebrae and skull, as well as internal damage to the brain, spinal cord and other organs.

[26][27][28] The US National Transportation Safety Board was also reported to be sending an accredited representative and four technical advisers to support the investigation process as the accident involved an American-built aircraft.

At 07:49:40 UTC the aircraft experienced a drop in vertical acceleration from +1.35G to -1.5G within 0.6 seconds, which likely caused unrestrained passengers to become airborne.

The current policy of crew members securing all loose items and equipment in the cabin during poor weather conditions would continue.

It also offered a full fare refund and S$1,000 to all passengers on board to cover immediate expenses and arrangements for relatives to fly to Bangkok where requested.

[31] On 22 May 2024, the CEO of Singapore Airlines Goh Choon Phong apologized for what happened on Flight SQ321 and expressed condolences while pledging full cooperation with the ongoing investigation.

A Singapore Airlines spokesperson stated that the aircraft also "met the safety requirements set by the aircraft manufacturer, passed stringent safety checks by SIA’s engineering and flight operations teams, and successfully completed a functional check flight before its return to service.