Flight History
On 20 May 2024, a Boeing B777-300ER, registered 9V-SWM, departed Heathrow Airport, London, for Singapore. The flight crew consisted of a Pilot-in-Command (PIC), a Captain, a Senior First Officer (SFO), and an Augmenting Pilot (AGP), also a Captain. The aircraft was cruising at Flight Level 370 (37,000 ft) over southwest Myanmar on 21 May 2024.
At approximately 07:30 UTC, the aircraft was approaching the southwestern region of Myanmar. The PIC was the Pilot Flying, and the AGP was the Pilot Monitoring. The flight crew reported being in Visual Meteorological Conditions (VMC). Prior to the event, the weather radar (WXR) displayed no returns on the navigation displays. The crew had selected the right WXR system, with the PIC's mode set to MAN and gain to MAX, and the AGP's mode set to AUTO and gain to CAL.
At 07:44:52, the crew requested a direct route to waypoint EKAVO, citing weather. Air traffic control offered a direct route to waypoint DWI, which was accepted. At 07:49:23, while cruising over southwest Myanmar at FL370, the aircraft encountered severe turbulence.
Injuries and Damage
The turbulence resulted in 56 persons being seriously injured and 23 with minor injuries. One person passed away; the cause of death was determined to be heart failure and lung edema. The aircraft diverted to Suvarnabhumi Airport, Bangkok, Thailand.
Weather Radar Observations
According to the flight crew, about 15 minutes prior to overflying waypoint PTN, no weather returns were displayed on the navigation displays. Both NDs were set to a 320 nm range. The AGP noted the immediate flight path was clear of clouds, and the PIC observed cirrus clouds in the distance but clear ahead. No cockpit discussion regarding clouds over Myanmar was recorded on the cockpit voice recorder.
The aircraft has two selectable WXR systems (left and right); only the right system was in use during the flight. The WXR control panel settings were as described above. The crew did not observe any faults or failure flags, and the WXR appeared to operate normally.
Subsequent Actions
After the turbulence encounter, the crew adjusted the navigation display ranges. The aircraft eventually landed safely in Bangkok.