Experts: Clear-air turbulence unpredictable and hazardous
PETALING JAYA: Sudden air turbulence may not occur frequently but it can have serious repercussions on passengers, crew and aircraft when it strikes, say aviation experts.

Former Air New Zealand aircraft performance engineer Jonathan Clark said such adverse weather conditions termed as clear-air turbulence (CAT) by aviators are unpredictable and hazardous to occupants of an aircraft in-flight.

He said when moisture in the air is low, CAT could go undetected by the weather radar of aircraft.

He said this after Singapore Airlines Flight SQ321 fell into an air pocket before encountering turbulence on Tuesday, forcing it to make an emergency landing in Bangkok.

A total of 211 passengers, including 16 Malaysians, were aboard the flight bound for Singapore.

Clark said bar carts used by flight attendants to serve food and beverages to passengers could pose a serious threat to lives if they are not safely secured even though they are heavy.

“During a major turbulence when an aircraft plummets, the bar cart can rise and fall on passengers if it is unsecured. This can potentially cause fatal consequences.

“Passengers who are not buckled with seat belts may get thrown around and suffer injury. It is best to stay seated with belts on at all times as it can save lives.

“Passengers do not seem to take this seriously until something like this occurs,” said the New Zealander when contacted.

Clark also holds a flying licence and has worked in the aviation industry for more than 40 years.

Retired airline pilot James Nixon said pilots face various weather conditions when they fly but stressed that having the seat belt on is crucial to personal safety.

The Australian-based aviator said passengers could suffer serious injury if they are hit by other occupants who are lifted off when an aircraft plunges and loses altitude rapidly.

Former MAS airline stewardess Lily Abdullah said wearing seat belts at all times is the best way to minimise the risk of injury when an aircraft runs into such trouble.

“The pilots of the Singapore Airline flight appear to have done their best and landed the aircraft safely. CAT is not common but it can happen,” said Lily, who operates a private air charter company at the Subang airport.

Another pilot who declined to be named said it is too early to say if it was the weather or an avionics malfunction of the aircraft that caused the steep descent.

“We will have to wait for the outcome of the investigations and see what caused it,” he said.

“It is too early to say for now although from early findings, it is believed to be the weather.”

Aviation expert Assoc Prof Dr Mohd Harridon Mohamed Suffian said the air turbulence faced by the Singapore Airline flight was difficult to be detected by current technology.

However, he said pilots who are proficient in the interpretation of data would be able to do the calculations on the probability of CAT at particular areas and proceed to avoid the region.

“Turbulence occurs when there are extreme pressure differentials and these create dynamic movements of air, which are erratic in nature,” said Mohd Harridon of UniKL Malaysian Institute of Aviation Technology.

“It’s important to ensure that the seat belt is fastened (at all times) as it would reduce the risk of being dynamically thrown in various directions at certain magnitudes during occurrences of turbulence,” he said.

Mohd Harridon also said passengers should adhere to the weight size and dimensions set by airlines of their carry-on baggage.

He said non-adherence to the stipulated guide would potentially lead to additional stresses and strains toward the overhead compartment of the aircraft.

“This subsequently would reduce the strength of the overhead compartment and increase fatigue as well,” he added.
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PETALING JAYA: Sudden air turbulence may not occur frequently but it can have serious repercussions on passengers, crew and aircraft when it strikes, say aviation experts.