It's the moment even seasoned air travelers dread. One moment you are sailing quietly at 37,000 feet. In the next thing, without warning, all hell breaks loose.
Severe turbulence can throw passengers and belongings throughout the cabin of an airplane, making for a terrifying ride. In the case of a Singapore Airlines Boeing 777 on a flight from London on May 21, the violence of the experience left a British man dead and more than thirty injured as the plane was forced to make an emergency landing in Bangkok.
Fatalities are unusual. But while turbulence does not normally cause deaths, airlines have long been aware of the potential harm it can cause to passengers, pilots and cabin crew.
Most concerning is the sudden, severe turbulence in the absence of clouds or storms, known as clear air turbulence (CAT), and for which pilots have little warning to passengers. According to Captain Mike Jenvey, a retired Netjets pilot, "clear air turbulence is not visible and often not visible using aircraft weather radars."
This is why aviation consultant John Strickland notes: "You should never take lightly when airlines recommend that you fasten your seat belt loosely during flight."
Research from Reading University shows that the number of CAT incidents could increase significantly between 2050 and 2080 due to stronger winds and increasing amounts of rough air due to climate change.
What exactly is turbulence?
Turbulence comes in different types. The most common thunderstorms at aircraft cruising altitudes are caused by thunderstorms.
Thunderstorms consist of huge expanses of rain clouds that often rise more than 53,000 feet (16 km) above the Earth's surface and are a major generator of air turbulence along the way. The supercooled air in the storms attracts winds from many kilometers around. A 2009 Met Office briefing document for commercial pilots advises pilots to stay at least 25 nautical miles away from a visible thunderstorm.
The other major type of turbulence that airline passengers experience is wind shear, a phenomenon that occurs when two air masses traveling in different directions cross each other, often leading to sudden changes in altitude or direction.
Captain Jenvey explains that "vertical wind shear and CAT cause an aircraft to fall very suddenly, then stop falling very quickly as stable air comes back in perhaps 100 to 1,000 feet later."
How bad can it get?
Turbulence is a minor annoyance for the most part. Pilots from airlines around the world are trained to avoid this to reduce the risk of passengers being thrown around. But in some cases it can cause fatalities.
A former White House official died last year due to "severe turbulence" on a private business plane during a flight between New Hampshire and Virginia. Three passengers on a Hawaiian Airlines service to Sydney were hospitalized in July 2023 after the flight experienced severe turbulence. Photos taken by those on board showed broken ceiling panels and dangling oxygen masks.
Strickland, the aviation consultant, noted that airlines use several methods to minimize the chance of a flight being affected by turbulence, such as weather forecasts, radar and reports from aircraft ahead.
But sometimes it's just not possible to avoid it completely. According to Marco Chan, senior lecturer at Buckinghamshire New University and former Hong Kong Airlines pilot: "It may not be possible to completely avoid the thunderstorm cluster as they can extend well over 50 nautical miles."
Could this cause the plane to crash?
Turbulence has caused airplanes to crash, although most of these accidents occurred many decades ago before modern safety analysis techniques came to light.
In November 2001, American Airlines Flight 587 from New York encountered wake turbulence shortly after departure - caused by a large aircraft taking off in front of it.
Pilot error in handling the sudden bumpy ride led to the Airbus A300 crashing, killing all 260 people on board, along with five others on the ground.
Another example is British Overseas Airways Corporation Flight 911, a scheduled flight between Tokyo and Hong Kong in March 1966. Shortly after takeoff, it broke up in mid-air, killing all 124 people on board.
Accident investigators found that the Boeing 707 "suddenly encountered abnormally severe turbulence over Gotemba City, creating a gust load significantly above the design limit."
Captain Jenvey today notes that "aircraft are designed for temporary overloading of the airframe," although he suggested that "a strong vertical wind shear or CAT encounter could overload the airframe to such an extent that an engineering inspection would be necessary afterwards. to land".
Are there areas or specific routes where turbulence is getting worse?
According to John Strickland, "Exposure is greater in different parts of the world. The South Atlantic, Africa and the Bay of Bengal are all places that come to mind where the incidence is higher."
He added: "There are discussions about whether climate change is influencing an increase in the number of events."
As a former long-haul pilot, Chan says there is a specific region near the equator that is known for particularly challenging weather and turbulence conditions.
"The Intertropical Convergence Zone (ITCZ) is an important meteorological feature in the tropics. It circles the Earth near the equator and influences weather patterns."
Captain Jenvey adds that "at lower levels - although sometimes higher if associated with a mountain range, such as the Andes in South America - types of mechanical turbulence, known as 'rotor' or 'mountain wave', are generated when the airflow is against the rocks are pushed. the side of a mountain or hill and pushed up."
Do you get a warning or does the pilot see it coming?
Turbulence is normally associated with thunderstorms and cloud formations, meaning pilots can see it coming in daylight. In this case, passengers are alerted by the seat belt sign turning on and warning them to fasten their seat belts for a rough ride.
Modern aircraft are equipped with weather radars in the nose that can detect future thunderstorms, allowing pilots to change course to avoid them. But as the name suggests, clear air turbulence remains invisible to those radars.
Chan adds that "thunderstorms, which may bring severe ice and turbulence, will be prominently displayed on the pilots' navigation display. Pilots are expected to navigate around thunderstorms while maintaining seat belts as a precaution."
What is the best way to prevent turbulence problems?
For an airline passenger, it's as simple as holding on to your seat belt. Injuries caused by turbulence usually result from people being tossed around by sudden impacts caused by the aircraft hitting an air pocket or entering a fast-moving air mass.
It also helps to keep your personal belongings safely stored in the seat pocket, under the seat in front of you or in the overhead locker.
Captain Jenvey says he advises air travelers to keep their seat belts fastened at all times unless it is necessary to get out of your seat. He explained that turbulence "can cause passengers who have not fastened their seat belts to get out of their seats very quickly and be pushed back very hard.
"When walking down the aisle of the aircraft, the sudden rise can cause passengers to hit their heads hard on the cabin ceiling and then fall down."
