‘Turbulence’ in the air

A very common announcement in flight is: “The seatbelt signs have been switched off, but please continue to put them on while seated.” This announcement Is made to ensure that passengers buckle up their seat belts and save themselves from a bumpy ride, which may be very turbulent and cause serious injuries. And there may be no warning beforehand. The effects of turbulence can range from mild movements to devastating disruption and danger for passengers, crew and aircraft integrity. Some experts are now saying that climate change is a major reason for the uptick in turbulence-related incidents.

So far this year, at least five serious incidents resulting in severe injuries have occurred. This has also led to the Hawaiian Airlines facing a lawsuit over a severe turbulence incident on a trans-Pacific flight. As per global estimates, each year, pilots the world over report an average of 5,500 encounters with severe or greater turbulence. And that number has increased in recent years.

In March this year, Alaska Airlines flight 889 from Portland in the US state of Oregon to Honolulu experienced extreme turbulence. Ingrid Weisse, a banker who was traveling on the Boeing 737 with her husband and two sons, told the US media that the aircraft began shaking so fiercely that it seemed as if the plane would come apart. "It got really, really violent. There was lots of screaming in the cabin. A flight attendant was hit by an ice bucket that became a projectile. So many people got sick from the sudden changes in altitude that flight attendants had to hand out more vomit bags,” Weisse was quoted as saying by ‘SimpleFlying’ — an aviation magazine. The turbulence lasted approximately 45 minutes. The incident was unlike anything the passengers or crew had experienced in the past, with a senior flight attendants telling Weisse that the turbulence was the worst she had seen in their 23 years in the business. Alaska Airlines confirmed the incident as "unexpected turbulence," but according to researchers, it is evident that a specific type of heavy and unpredictable turbulence is becoming more common.

This one incident is typical of any major turbulence that occurs in air, putting the safety of the air travellers and the aircraft at serious risk. So, the announcements made by the pilots or flight attendants have to be adhered to by passengers in all seriousness. What is turbulence, really? It is defined as irregular air movement that causes erratic changes in the altitude or the angle of the plane, which feels like bumpiness, choppiness or tossing for the people on board. Atmospheric pressure, the air around mountains and weather fronts or storms can all cause turbulence. Jet streams — or narrow bands of strong wind in the upper levels of the atmosphere — are also a common cause of turbulence. One of the most dangerous kinds of turbulence is what is known as clear-air turbulence, which gives no visible warning and often occurs when pilots do not have the ‘fasten seatbelt’ sign turned on. "It's completely invisible to the naked eye, to the radar, to satellites," says a weather researcher quoted by SimpleFlying. "The only information we have about it, really, is when a plane goes through it," he said. For Indian flight region, flying over most of the Himalayan ranges is prohibited, just because of such turbulence.

The US Federal Aviation Administration (FAA) defines serious injuries as those that require hospitalisation for over 48 hours, or result in fractured bones, severe muscle or tendon damage, harm to internal organs or second or third-degree burns. As airlines are not required to report more minor injuries, the total number of injuries is thus underreported. According to a 2021 report of the US National Transportation Safety Board (NTSB), the majority of passengers who are seriously injured by turbulence were not wearing their seatbelts, using the restroom or walking up or down the aisle. Injuries can be caused by luggage falling out of overhead bins, people stumbling or being tossed into or out of their seats or food carts ramming into passengers. The NTSB report found the same was true for crew members who were most commonly injured while preparing the cabin for landing or doing cabin service like serving food or drinks or collecting trash. Turbulence can also mean damage to the aircraft. About 65,000 flight encounters are caused by turbulence every year and about 5,500 encounter severe turbulence, according to the National Center for Atmospheric Research.

In this context, the US-based National Public Radio (NPR) Network quoted a professor of atmospheric science at the University of Reading in England, Paul Williams, to say that "clear air turbulence", the most dangerous type which cannot be seen or predicted, is becoming more frequent. This type of turbulence occurs without clouds or inclement weather. At altitudes above 15,000 feet, it is instead caused by wind shear, meaning sudden changes in the speed of the wind and its direction. Williams said the reason for the uptick in clear-air turbulence is climate change. Since global temperatures are increasing due to the rising levels of greenhouse gasses such as carbon dioxide, the jet stream has more wind shear. "Since satellites began observing in 1979, the amount of wind shear has grown by 15 per cent," Williams told the NPR. The professor and a team of his colleagues, who did a follow-up study using climate model simulations, determined that severe turbulence is on track to worsen over the years. The findings reportedly indicated that clear-air turbulence in the middle of the Northern Hemisphere could triple in the next three to six decades, depending on the levels of greenhouse emissions in the future. "The problem is that clear-air turbulence cannot be spotted because it's above the clouds," said Carlo Scalo, an Associate Professor at Purdue University. "You don't really see it. It's just fast air moving into slow air and vice versa." Climate change is causing more instability in the jet streams and making wind speeds faster, which will cause more turbulence when the skies appear clear. By 2050, pilots around the world can expect to encounter at least twice as much severe clear-air turbulence, Williams found in his research.

Clear-air turbulence caused a Lufthansa flight traveling from Austin in Texas to Frankfurt in Germany to unexpectedly drop 1,000 feet on March 2. The sudden turbulence occurred during meal service, when crew and passengers were moving around the cabin. The plane was diverted to Washington Dulles International Airport and seven people were hospitalised. Regardless of what kind of turbulence a flight may be experiencing, experts say the best thing for passengers to do to avoid injury is to keep their seatbelts buckled, follow carry-on restrictions and listen to instructions from pilots and flight attendants.

The global airlines’ body, International Air Transport Association (IATA), had launched an initiative in 2018 which is now in a live trial phase, with several airlines around the world sharing turbulence data for the first time. IATA and airline trial participants say the platform, called ‘Turbulence Aware’, has the potential to make flying safer, more comfortable and more fuel-efficient, especially over less-travelled oceanic routes. "This is a paradigm shift," said Brent King, the former Qatar Airways pilot who is IATA's head of flight operations efficiency. "It is revolutionising the way we manage real-time turbulence data. So far, airlines have mainly relied on their own data to set flight plans and navigate around turbulence. Pilots also rely on live reports over the radio from nearby pilots. Katya Vashchankova, head of the ‘Turbulence Aware’ programme, said some carriers might partner with three or four other airlines on turbulence data sharing. But until now, the industry has had no central repository for such data.

At present, about 20 airlines are participating in the IATA’s Turbulence Aware Platform with more than 1,900 aircraft providing data daily. In 2022, a total of 31 million reports were generated. But no Indian carrier has so far become a member of this IATA programme. Air India is already operating long-haul, non-stop flights over the North Pole, the Pacific and the Atlantic. Becoming a member of ‘Turbulence Aware’ would enable Indian airlines to get current data on turbulence. Joining this IATA initiative would be significant in the context of the Indian carriers gradually launching more and more long-haul international flights.

Views expressed are personal