Two theories for turbulence that shook Emirates flight

Mumbai/Kochi: There were two theories for the turbulence that shook an Emirates flight from Dubai to Kochi on Sunday. While Emirates officials said the aircraft encountered turbulence “due to cloud’’, aviation meteorologists said that the route did not have any thunderstorm clouds in the morning and the aircraft could have flown into an air pocket. What is clear though is that there surely was poor weather enroute.
“Aircraft flying that route were all asking for deviations to avoid a thunderstorm cloud. The Emirates aircraft also asked for a deviation when it was over the Arabian sea north-west of Mangalore. The flight was cleared to proceed to Calicut,’’ said an air traffic controller from Mangalore.
An aviation meteorology expert had a different take. “The upper air wind/temperature charts issued by World Area Forecast centre did not show any thunderstorm clouds on that route in the morning. But it showed a slight wind shear condition (winds changing speed and direction rapidly) off the coast of Mangalore. At 35,000 feet, the chart shows strong westerly wind with a speed of 60 kts dropping to 25-30 kts. It’s one of the indicators of clear air turbulence (CAT).’’
Unlike thunderstorm clouds, CAT cannot be detected on an aircraft’s airborne weather radar. But it can be predicted by studying upper wind charts with indicators such as wind shear. The Emirates aircraft may have encountered CAT.
“The aircraft encountered a weather cloud near Bangalore and experienced a short period of heavy turbulence. The drop in altitude was minor, a descent of 200 feet, and the aircraft landed safely,’’ said Majid Al Mualla, Emirates senior vice-president, commercial operations, west Asia and Indian Ocean.
26/04/10 Manju V & Ananthakrishnan G/Times of India

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Categories: Foreign Apr 2010, Safety Apr 2010