The Singapore Transport Safety Investigation Bureau (TSIB) has released a preliminary report on the recent turbulence incident involving Singapore Airlines flight SQ321.
The incident, which occurred on 21 May 2024, tragically resulted in one passenger fatality and multiple injuries.
On May 21st, 2024, Singapore Airlines flight SQ321 flying from London to Singapore encountered severe turbulence while traversing Myanmar’s airspace.
The Singapore Transport Safety Investigation Bureau (TSIB) has now outlined the sequence of events. This is based on data they retrieved from the flight data recorder (FDR) and cockpit voice recorder (CVR).
Singapore Airlines SQ321 London-Singapore
SQ321 departed London on May 20th and proceeded without any major issues until encountering turbulence ten hours into the flight.
The investigation team, comprising TSIB investigators alongside representatives from the US National Transportation Safety Board (NTSB), Federal Aviation Administration (FAA), and Boeing, have analyzed the data to reconstruct the events.
Unforeseen Updraft Triggers Sequence of Events
At approximately 7:49 AM UTC, while flying over the southern region of Myanmar at a cruising altitude of 37,000 feet, the aircraft encountered an unexpected updraft.
This powerful current of rising air caused the plane to experience an uncommanded increase in altitude, reaching a peak of 37,362 feet.
The autopilot system initially responded by pitching the aircraft downwards to maintain the designated altitude.
Rapid G-Force Changes Cause Injuries
Almost simultaneously with the altitude change, the aircraft experienced a dramatic shift in G-force, a measurement of the force exerted on a body due to acceleration.
The recorded vertical acceleration fluctuated rapidly between positive (+ve) 1.35G and negative (-ve) 1.5G within a mere 0.6 seconds.
This rapid fluctuation likely caused significant problems within the cabin. Passengers who were not properly secured in their seats would have been thrown upwards with the positive G-force and then slammed back down with the negative G-force.
This violent motion is believed to be the primary cause of passenger injuries.
Pilot & Crew Response Ensured Safe Landing
The pilots onboard Singapore Airlines flight SQ321 reacted swiftly and decisively in this critical situation. Recognizing the autopilot’s limitations in handling such extreme turbulence, they promptly disengaged it and took manual control of the aircraft.
This allowed them to stabilize the plane and counter the erratic movements caused by the turbulence.
While managing the aircraft, the pilots also requested medical assistance upon learning about the injured passengers onboard.
Diversion to Bangkok
Following the turbulence encounter, the pilots diverted the flight to Suvarnabhumi Airport in Bangkok, Thailand.
The data retrieved from the FDR indicates that the remainder of the journey to Bangkok was uneventful, with the aircraft experiencing no further severe turbulence.
SQ321 landed safely at approximately 8:45 AM UTC.
Summary
The TSIB’s preliminary report provides valuable insights into the events that unfolded during SQ321’s encounter with severe turbulence.
However, the investigation is still ongoing. The team will continue to analyze the data in detail to determine the exact cause of the turbulence.
They will identify any potential areas for improvement in aircraft safety protocols and passenger preparedness for such situations.
This tragic incident serves as a stark reminder of the unpredictable nature of air travel and the importance of adhering to safety regulations, particularly regarding seatbelt use during all phases of the flight.
Future updates from the TSIB investigation are expected to shed more light on the contributing factors and potential recommendations to prevent similar occurrences.
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