HK Observatory links Singapore Airlines incident to convective turbulence, foresees more due to climate change

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29th May 2024 – (Hong Kong) Recently, Singapore Airlines Flight SQ321 experienced severe turbulence on its course, necessitating an emergency descent in Thailand. This unfortunate event led to one death and 55 injuries. Emerging analysis from the Hong Kong Observatory suggests that this incident could be attributed to convective turbulence, potentially exacerbated by climate change.

On 21st May, at approximately 7.50am Coordinated Universal Time, Flight SQ321 encountered violent atmospheric disturbances over the Irrawaddy Delta in Myanmar. Data indicated that while the flight’s altitude remained relatively steady for most of its duration, it experienced significant vertical speed fluctuations around the time of the incident. The Root Mean Square of Vertical Acceleration (RMSVA) peaked at over 0.4g, surpassing the 0.3g threshold commonly associated with severe turbulence.

The Hong Kong Observatory’s recent blog post detailed its analysis of the event, utilising Automatic Dependent Surveillance-Broadcast (ADS-B) data. The observatory noted that satellite images showed mature convective clouds in the vicinity of the turbulence, some displaying overshooting tops – a sign of strong updrafts and potential turbulence.

Moreover, animation from satellite data clearly depicted the rapid development of convective cloud systems over the delta, coinciding with active lightning in the region. This lends weight to the hypothesis that the severe turbulence was related to convective activity in the clouds, possibly involving Cloud-Induced Turbulence (CIT), either within or near the cloud formations.

The Observatory highlighted that different types of atmospheric turbulence include convective and clear-air turbulence, with the latter often undetectable with traditional radar systems. This incident, however, was linked to the more detectable convective type, suggesting a direct interaction with active weather systems.

In light of this event and another turbulence incident involving Qatar Airways Flight QR017 on May 26, the Observatory has warned that such occurrences may become more frequent and intense due to climate change. The shifting climate patterns are likely contributing to increased instability in the atmosphere, making turbulence both more likely and more severe.

For air travellers, the Observatory recommends always wearing seat belts while seated, as flights at cruising altitudes—typically between 31,000 and 38,000 feet—are generally smooth but can still be susceptible to sudden turbulence.

As part of ongoing efforts to enhance aviation safety, the Hong Kong Observatory has developed a new system integrating satellite proximity forecast outputs with numerical weather prediction models. This unified system is designed to provide seamless significant convective weather forecasts. The Observatory continues to work closely with airlines, providing updated weather information through electronic flight bags to crew members, aiming to enhance both safety and operational efficiency in aviation.