A former pilot has said that the Singapore Airlines flight, which was caught in a severe turbulence leading to the death of one passenger, could have hit an area called the Intertropical Convergence Zone (ICZ). According to NASA Earth Observatory, it is a region that circles the Earth near the equator, where the trade winds of the Northern and Southern hemisphere come together. Due to the intense heat of the Sun and warm water of the equator in this region, the humidity content is high. Aided by the convergence of the trade winds, the buoyant air rises. As the air rises it expands and cools, releasing the accumulated moisture in an almost perpetual series of thunderstorms.

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Marco Chan, a former commercial pilot and lecturer in aviation at Buckinghamshire New University, said in such a scenario, pilots’ options may have been limited.

“With turbulence of such magnitude, it is likely the Singapore Airlines flight was navigating through difficult thunderstorms,” Mr Chan told the Wall Street Journal (WSJ).

Further explaining the notorious storm system, he told The Guardian, “Thunderstorms are prominently displayed on the pilots’ navigation display – but it may not be possible to completely circumvent the storm cluster as they can stretch well over 50 nautical miles.”

What is turbulence?

It is a phenomenon caused by meeting of air at different temperatures, pressure or velocity, where different wind patterns collide.

One of its dangerous form is the clear-air turbulence, which can take plane pilots by surprise and occur without warning.

The Boeing 777 jet of Singapore Airlines had to make an emergency landing in Thailand after being hit by deadly turbulence.

Geoffrey Kitchen, a 73-year-old British passenger, died likely due to a heart attack on flight SQ321, said Kittipong Kittikachorn, general manager of Suvarnabhumi Airport in Bangkok.

Nearly 60 passengers were injured in the May 21 incident.

Singapore Airlines on Wednesday said it is fully cooperating with relevant authorities in the investigation, adding that all the passengers were examined and treated at the airport.