PUBLISHED ONMay 19, 2026 10:21 AMUPDATEDMay 19, 2026 11:54 AMBYKhoo Yi-HangThe weather radar in the cockpit of Singapore Airlines (SIA) flight SQ321 may have malfunctioned amid turbulence that resulted in the death of a British national in 2024 and injuries to other passengers, according to a report by the Transport Safety Investigation Bureau (TSIB) published on Tuesday (May 19).
SQ321 departed London Heathrow for Singapore at around 9.40pm UTC (5.40am Singapore time) on May 20, 2024.
At 7.49am UTC the next day, as the plane cruised over southwest Myanmar, it was abruptly hit by turbulence that lasted over a full minute.
Despite the best efforts of flight crew to take control, 80 passengers on board the flight suffered injuries, while the British passenger died after suffering complications with his heart and lungs.
The Boeing 777-300ER was carrying a total of 229 passengers including crew.
After receiving reports of multiple injuries in the cabin, the flight crew declared mayday to air traffic control in Yangon, Myanmar, and was directed to land in Suvarnabhumi Airport in Bangkok.
Arriving at 8.45am, medical personnel helped treat the injured, transporting them to hospitals.
According to the TSIB report, the turbulence likely resulted from a rapidly growing cloud which caused significant vertical air movements in what is known as convectively induced turbulence (CIT).
CIT is associated with convective clouds and thunderstorms and can take place outside of visible storm clouds, making it hard to predict.
TSIB said that the flight crew reported no weather radar returns shown on their navigational displays 15 minutes prior to the incident as they flew over southwest Myanmar.
Both the pilot and the co-pilot also did not see any clouds as they looked out of the cockpit window.
After the turbulence incident, the pilot reportedly removed the sunshade at his side window, but did not share what he saw.
"We hit something but I was on max," he said, referring to the intensity of weather radar returns on his navigation display.
"I was on max, I don't see anything here."
However, four other aircraft flying in the vicinity — but not along the same flight path — noted widespread clouds over Myanmar.
"The investigation team is unable to understand why the flight crew of the occurrence flight did not see the widespread clouds," TSIB said.
TSIB also shared the possibility that the weather radar had failed to pick up on clouds in the area — known as no-painting.
The bureau reasoned that if the pilots had noticed anything amiss about the weather, they would have discussed it and their conversation would have been recorded on the cockpit voice recorder.
Because the co-pilot had adjusted the range on his navigation display but still had no returns on his weather radar, no conversation was recorded regarding the weather.
The pilot had also expressed surprise at the empty radar despite having set his to "max", TSIB stated.
Additionally, the bureau reviewed SIA's Boeing 777 fleet maintenance records from May 2023 to July 2025.
Among 29,000 flights, there were 20 reports of no-painting without a fault message, one of which was logged by the occurrence aircraft on May 15, 2024.
"It is likely that the occurrence aircraft experienced another no-painting situation," TSIB said.
Of the 29,000 flights, there were also 12 reports of under-painting — where weather intensity is underrated — by the radar, of which two were reported by the occurrence aircraft on April 29, 2024, and May 1, 2024.
SIA has a reliability programme for recurring defects for all aircraft systems, where if the same defect occurs to the same aircraft three times within 10 days, it will take additional troubleshooting action.
While three instances were recorded for the occurrence aircraft, they did not fall within the 10-day period.
However, the weather radar's manufacturer conducted tests on the radar and could not replicate the issue, concluding that there was no evidence that the radar failed to detect and display weather encountered as the aircraft flew over southwest Myanmar, the report also stated.
TSIB added: "The investigation team opines that the possibility of no-painting and under-painting without fault messages cannot be ruled out."
The bureau also put forth recommendations for both the airlines and manufacturers.
AsiaOne understands that airlines and manufacturers that have received TSIB's recommendation are obliged to respond within 90 days with information on their intent to accept and implement the recommendation.
Should they choose not to accept it, they ought to provide an explanation for doing so.
Meanwhile, SIA has also begun sending reports of the weather radars' issues on its B777-300ER fleet to both the aircraft manufacturer and weather radar manufacturer for information and follow-up actions.
Previously, for the weather radar, SIA would only send reports should an aircraft's radar experience at least three defects within 10 days.
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khooyihang@asiaone.com
