A SIA Boeing 777-300ER taking off at Zurich
Photo Credit: Aero Icarus (https://tinyurl.com/3b5zy4b5)
The Boeing 777 severe encounter with turbulence
On May 21, a Singapore Airlines Boeing 777 diverted to Bangkok and made an emergency landing at Suvarnabhumi Airport after encountering severe turbulence, leaving one dead and about 30 injured.
Reuters reported that the plane dropped 6,000 feet from its original cruising altitude of 37,000 feet near the Bay of Bengal while flying from London to Singapore.
I had a similar experience at the same spot years ago on a flight from London to Kuala Lumpur. Suddenly, I was tossed violently around, but thankfully, I was secured by my safety belt while resting in my sleeping bunk. Fortunately, no one on board was injured as everyone was securely fastened with safety belts.
Turbulence is categorized into four intensities: light, moderate, severe, and extreme. In ‘light’ turbulence, small unsecured objects may get dislodged. ‘Moderate’ turbulence involves consistent bumps and straining against belts. ‘Severe’ turbulence violently forces passengers against their seat belts, and ‘extreme’ turbulence can forcefully toss the aircraft or cause damage.
Severe turbulence encounters are rare as pilots generally know how to avoid them, except when they inadvertently fly into clear air turbulence, which cannot be seen. However, careful analysis of horizontal wind shear on computer flight plans can sometimes reveal turbulence ahead.
Most flight planning systems consider wind speed 1,000 feet below and 1,000 feet above the cruising level. If shear rate values increase along the route, it’s time to warn the cabin crew of approaching turbulence during the preflight briefing.
Severe turbulence associated with thunderstorm clouds is easily observed on radar, and pilots avoid them like the plague. Pilots reduce speed, akin to a car approaching a road bump, and attempt to fly around or above such clouds whenever air traffic permits.
The good news is that the Boeing 777 is a robust plane, with wings built strong enough to withstand up to 150 percent of the force they are ever likely to encounter in flight.
Turbulence is generally caused by the relative movement of disturbed air through which an aircraft is flying, especially over mountains, near jet streams, uneven heating surfaces, or in thunderstorms.
The most severe turbulence is usually associated with the updrafts and downdrafts within the thunderstorm clouds. These conditions are most prevalent in the Bay of Bengal area and its vicinity. Avoidance or rerouting around known thunderstorm clouds by pilots is key to reducing severe turbulence encounters.
Passengers should always keep their belts fastened, even when the seat belt signs are off in case of unforeseen turbulence.
With that, I wish you all a safe flight.
Note: This article is for general information only and not to be cited in any actions.
View a video ‘Passengers carried out of flight SQ321 after making emergency landing in Bangkok’
here https://www.youtube.com/watch?v=k84NdhYa21I