Clear air turbulence, like that which hit a Singapore Airlines flight this month, cannot be detected by technology. Photo: AP / Sakchai Lalit
Clear air turbulence, like the deadly one experienced by the Singapore Airlines flight SQ321, cannot be picked up using technology, an aviation expert says
A man died and 104 passengers were injured after the flight hit sudden turbulence above Myanmar on 21 May.
Just five days later, a Qatar Airways flight encountered turbulence above Turkey, injuring 12 passengers and crew.
Airline accident investigator and lecturer at Ohio State University, Dr Shawn Pruchnicki said both incidents seemed like they were caused by Clear Air Turbulence (CAT)
"That's a type of turbulence that is not associated with cloud. It's not associated with thunderstorms."
Pruchnicki said aircraft systems were only able to pick up turbulence when there was moisture - rain- involved.
"It uses the moisture flying around in the air to detect turbulence.
"When it's clear air turbulence those sensors do not pick that up," he said.
Pruchnicki said he was not aware of any technology that could help pilots pick up CAT ahead of time. The only way to predict it was to be aware of jet streams, he said.
" Jet stream is that tunnel of air that goes all the way around the world. There's several of them and you have very smooth air around them."
"Think about a fast moving river that dubs into a very still pond," he said.
"It's that boundary between the two [that] is basically what clear air turbulence could be described as."
He said having a good understanding of the upper winds could sometimes help foretell the presence of CAT.
"At this point in time, we just don't have any science where we can predict it."
Pruchnicki believed CAT could happen at any time of the day.
And he said climate change could eventually contribute towards making turbulence more frequent.
Flights were most likely to encounter turbulence around the equator due to the upper wind patterns, he said.
"It's very common for pilots to turn on the seatbelt side when passing through the equatorial region."
Pruchnicki said it was extremely important for passengers to keep their seat belts fastened and have it "snug", regardless of what the seatbelt indicated.
"I know it's important to get up and walk around and stretch your legs a little bit, but try to keep that to a minimum and try not to spend too much time at the extreme points of the aircraft - all the way in the back or all the way in the front."
He said an airplane was like a seesaw with "the motion at the ends are more extreme than they are in the middle".
"It's understandable you go back, you stand in line, you wait for the lavatory... maybe you talk to someone for 10 minutes. Then go back to your seat, put your seat belt on."
