In light of the recent event involving a Singapore Airlines flight from London to Singapore on 21 May 2024, there is undoubtedly some unrest, maybe even panic, about what exactly turbulence is and how it affects flights.
For clarity, the Boeing 777-300ER plane was approximately 10 hours into its journey and in the middle of serving meals when it encountered turbulence while flying over Myanmar’s Irrawaddy Basin.
The severe turbulence tossed passengers and crew around the cabin, ultimately necessitating an emergency landing in Bangkok. As of the afternoon of Wednesday, 22 May, there have been one reported death and more than 70 people injured.
For frequent flyers, turbulence is very commonly experienced in almost every flight, to the extent where we would simply reassure ourselves, saying, “This will pass in time.”
However, incidents like this always make us uneasy.
Turbulence, while common, is still an unpredictable adversary, akin to a sudden thunderstorm while driving on the road.
We break down 10 facts about this natural phenomenon to you.
How is Turbulence Created
Most turbulence occurs in clouds where wind moves up and down, according to Simon King from BBC Weather, who used to be an officer from the Royal Air Force of the United Kingdom.
These turbulences are caused by a combination of thunderstorms, winds, the plane’s jet stream, and sometimes flying close to high mountains.
Usually, this turbulence is mild, but in bigger clouds, like thunderstorm clouds, the air can move wildly and cause moderate to severe turbulence.
How Common is Turbulence?
Turbulence-related incidents are common, as per a 2021 study by the US National Transportation Safety Board. Between 2009 and 2018, turbulence was responsible for over a third of reported events, with most causing one or more serious injuries, but no damage to the aircraft. However, fatal turbulence in air travel remains extremely rare.
“It’s a very unusual and rare event. As far as I know, it’s been over 25 years since a passenger was killed by turbulence on a commercial airliner,” stated Paul Hayes, director of safety at the UK-based aviation data group Cirium Ascend.
The last fatal turbulence-related accident recorded in Cirium’s database occurred in 1997 involving a United Airlines Boeing 747, whereby the flight departing from Tokyo en route to Hawaii encountered severe turbulence believed to be linked to a Jet Stream over the Pacific Ocean.
Multiple passengers and crew members suffered serious injuries, resulting in one passenger’s death.
There are Many Kinds of Turbulences
Australia’s Civil Aviation Safety Authority (CASA) classifies turbulence into six categories:
- Light chop: Mild, fast, and somewhat rhythmic bumpiness without significant changes in aircraft altitude or attitude.
- Light turbulence: Mild, erratic changes in aircraft altitude and/or attitude. Passengers may feel a slight strain against seatbelts, and unsecured objects might move slightly. Cabin service can continue, and walking is usually not difficult.
- Moderate chop: Fast bumps or jolts without significant changes in aircraft altitude or attitude.
- Moderate turbulence: Changes in aircraft altitude and/or attitude occur, but the aircraft remains under control. It typically leads to variations in airspeed. Passengers feel noticeable strain against seatbelts, unsecured items are dislodged, and cabin service and walking become challenging.
- Severe turbulence: Large, sudden changes in aircraft altitude and/or attitude. This turbulence often causes significant fluctuations in airspeed. Passengers are forcefully pushed against seatbelts, unsecured objects are thrown around, and cabin service and walking become impossible.
- Extreme turbulence: The aircraft is violently thrown about and is nearly impossible to control. This level of turbulence may result in structural damage.
There’s also something called “clear air” turbulence, which, as the name suggests, happens in clear skies and can’t be seen. This type is more troublesome because it’s hard to detect.
Clear air turbulence occurs around the jet stream, a fast-moving “river” of air usually found at 40,000-60,000 feet, explains aviation expert and pilot Guy Gratton.
The jet stream can have a speed difference of up to 100 mph compared to the surrounding air, he says. The friction between the slower and faster air around the jet stream causes turbulence.
This turbulence is always present and moves around, making it hard to avoid.
How is Turbulence Monitored and Measured?
Meteorologists use various algorithms, satellites, and radar systems to create detailed aviation forecasts, predicting conditions like cold air, wind speed, thunderstorms, and turbulence. They identify where and when turbulence might occur.
Jennifer Stroozas, a meteorologist at the National Weather Service’s Aviation Weather Center, describes turbulence as “one of the more challenging things to predict.”
Pilots rely on these forecasts and guidance from air traffic controllers to navigate around turbulent areas by adjusting their altitude for a smoother ride. This may involve flying higher or lower than the altitude where turbulence is forecasted, potentially consuming more fuel than planned, which can be costly.
Robert Sumwalt, former chairman of the National Transportation Safety Board and current head of an aviation safety center at Embry-Riddle Aeronautical University, emphasizes that it’s impossible to prevent or predict all turbulence.
“There’s always the possibility of unexpected rough air,” Sumwalt states. “But generally, it’s not dangerous and won’t damage the airplane.”
Stroozas adds that turbulence poses a greater risk to small planes, which are more sensitive to changes in wind speed, compared to larger commercial airliners.
Turbulence is Generally Harmless
Despite the nerve-wracking and uncomfortable feelings turbulence can give a passenger, planes are built to handle the worst turbulence they might encounter, says Mr Gratton, an aviation professor at Cranfield University.
He explains that it’s “unlikely” turbulence will ever destroy a plane.
However, in any case, turbulence is not good for an aircraft, so pilots try to avoid it or slow down and turn on the seatbelt sign.
In extreme cases, turbulence can cause damage to a plane due to strong winds.
Severe turbulence can be dangerous to passengers because it can cause violent movements, throwing anyone not wearing a seatbelt around the cabin.
Despite this, aviation safety experts say deaths and injuries from turbulence are rare.
John Strickland, an aviation expert, notes that injuries from severe turbulence are “relatively rare” compared to the millions of flights each year.
According to the US National Transportation Safety Board, there were 163 “serious turbulence injuries” on US airlines between 2009 and 2022, averaging about 12 per year.
Turbulence Can Usually be Detected Beforehand
Pilots often know about turbulent conditions ahead and can turn on the seat belt sign when approaching turbulence. They are guided by pre-flight weather reports, the plane’s radar, and reports from other aircraft in the area.
However, sudden clear air turbulence (CAT) can catch crews off guard, leaving little time to react.
“If it’s unexpected, it’s a bit late,” said retired pilot Hugh Dibley, an expert at the Royal Aeronautical Society. “You hope to get warnings from other aircraft and slow down to minimise the effects.”
Chris McGee, a commercial pilot for over 20 years, said that clear air turbulence is “almost impossible to predict” and can appear “out of the blue.”
Ms McGee noted that while turbulence isn’t rare, experiencing severe turbulence is “phenomenally rare.” In her career, she encountered severe turbulence once and heard of “two, possibly three incidents of something that extreme” from fellow pilots.
Turbulence May Have Gotten Worse Over the Years Due to Climate Change
For some time now, it has been recognized that climate change is causing more turbulence during flights, and this trend is expected to worsen, according to reports.
In June last year, a study from Reading University discovered that in a typical spot in the North Atlantic— one of the world’s busiest routes— the total annual duration of severe turbulence increased by 55% from 17.7 hours in 1979 to 27.4 hours in 2020.
Moderate turbulence also rose by 37% from 70.0 to 96.1 hours, and light turbulence increased by 17% from 466.5 to 546.8 hours.
Professor Paul Williams, an atmospheric scientist who co-authored the study, commented, “My message from this is we need to do something otherwise flights will become more turbulent in the future [as global heating increases further].”
Professor Paul Roundy, from the University of Albany, mentioned on X on Tuesday that the 55% increase in “a very infrequent signal gives a real, but small, change in absolute risk.”
He pointed out that “it’s not something a randomly selected passenger should worry about,” before adding: “Airline travel of the future won’t be fraught with wings ripped off planes, or have thousands of dead or injured passengers.
“It will mostly look like it does today.”
What Can Passengers Do to Stay Safe?
Due to the frequent occurrence of clear air turbulence, the best way to prevent related injuries is one simple but effective measure – always fasten your seat belt.
Ms McGee advises passengers concerned about their safety to follow the cabin crew’s recommendations and keep their seat belts loosely fastened at all times.
She mentions that this is standard practice in the flight deck and will help protect passengers.
Weatherilt suggests that passengers should always wear their seat belts, even when the sign is off. In rare cases of unexpected turbulence, those who are injured are often not wearing their seat belts.
Weatherlit also notes that during severe turbulence, aircrew have a higher risk of injury as passengers are usually seated with seat belts fastened, while crew members may be standing.
“Always keep your seat belt fastened because accidents can happen,” they emphasise. “Even if it’s fastened a bit loosely, it can prevent serious injury.”
Take Special Care of Children
Children held on their parents’ laps during flights may be particularly at risk of injuries from turbulence. The sudden and sharp movements can cause the child to fall off their parent’s lap.
In one instance, a baby girl on a United Airlines flight was “sent flying” from her parents during turbulence and landed on a passenger sitting several rows ahead (fortunately, the baby girl was unharmed).
Recently, the National Transportation Safety Board in the United States urged airlines to install dedicated safety seats for infants and small children, similar to those used in vehicles.
NASA is developing an early-warning system using ground-mounted infrasonic microphones to detect clear-air turbulence hundreds of miles away.
Austria-based startup Turbulence Solutions is working on technologies to eliminate up to 80% of turbulence.
Industry experts caution that any new aircraft systems must undergo rigorous testing to ensure they work reliably. This process takes years before the technology can be validated. Airlines typically have to cover the costs of these upgrades.
While turbulence remains an inherent aspect of air travel in the foreseeable future, you can take comfort in knowing that airlines and aviation authorities are continually striving to ensure safety and enhance the flying experience.