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Investigators found that the radar could have been “under-painting” or “no-painting” \u2013 under-detecting or not detecting inclement weather altogether.<\/p>\n
A review of SIA’s Boeing 777 fleet maintenance records across around 29,000 flights found 12 cases of weather under-detection and 20 cases where weather was not detected at all.<\/p>\n
Among these, two cases of under-detected weather were recorded on SQ321 on Apr 29 and May 1, 2024, and a third \u2013 where weather went entirely undetected \u2013 was logged on May 15, six days before the incident.<\/p>\n
In all three cases, pilots reported no fault messages on the displays, and post-flight tests found no faults. The issue was not escalated to the manufacturer because SIA’s procedures then required escalation only when the same defect occurred on the same aircraft three times within 10 days \u2013 a threshold the three reports did not meet.<\/p>\n
Further evidence emerged after the incident, when pilots ferrying SQ321 from Bangkok back to Singapore on May 26 found that one of the radars was under-detecting weather.<\/p>\n
“The investigation team opines that, taking into consideration the maintenance records, the ferry flight crew’s observation of under-painting does suggest an issue of under-painting of the weather radar system,” the report said.<\/p>\n
The manufacturer conducted tests on SQ321’s radar in various conditions, including different temperatures and in-flight, and found no evidence that the system had failed to accurately detect and display weather during the incident flight.<\/p>\n
Investigators nonetheless concluded that the flight crew’s account was credible. Had inclement weather shown up on the flight displays, it was “likely” the crew would have discussed it, but no such discussion was captured by the cockpit voice recorder.<\/p>\n
After the turbulence, the pilot-in-command expressed surprise that he had not seen any dangerous weather on the navigation displays.<\/p>\n<\/div>\n