DALLAS — Southwest Airlines (WN) has announced it is ending cabin service earlier on flights.

An airline spokesperson said flight attendants will start preparing the cabin for landing at 18,000 feet instead of 10,000 feet to reduce the risk of in-flight turbulence injuries for crew and passengers.

Turbulence in flight involves the airplane's irregular, annoying, and unpredictable motion, which causes it to fly in an undesired attitude, altitude, and direction. If this situation is severe and uncontrolled, it can injure passengers and crew and damage the airframe.

Turbulence-related fatalities are rare, but injuries have risen over the years. More than one-third of all airline incidents in the US from 2009 to 2018 were related to turbulence, mainly resulting in serious injuries but no plane damage.

In May, a 73-year-old man died on a Singapore Airlines (SQ) flight due to severe turbulence. Flight SQ321, departing from London Heathrow Airport (LHR) on May 20, 2024, encountered severe turbulence during stormy weather and was forced to make an emergency landing at Suvarnabhumi International Airport (BKK) in Bangkok.

The SQ Boeing 777 aircraft, carrying 211 passengers and 18 crew members, experienced a rapid plunge while flying at approximately 37,000 feet. Tragically, at least one passenger, a British citizen, has died as a result of the turbulence, and several others have been injured.

The incident occurred amid stormy weather conditions, but what are the other causes?

Types of Turbulence

There are four main types of turbulence:

1. Clear-air Turbulence: This type of turbulence occurs when large air masses of high or low pressure collide or when encountering high-level jet streams. As we'll see, clear-air turbulence incidents have increased in the last four decades, and avoiding them by planning flight routes that steer clear of these areas is never easy.
2. Wake Turbulence: Flying in the wake of a preceding aircraft that has disturbed the air generates wake turbulence. Consider the visible wake left by a large boat. To avoid wake turbulence, aircraft maintain lateral separation, fly at different altitudes, or offset their tracks.
3. Mechanical Turbulence: Strong winds passing over mountains cause mechanical turbulence. This generates waves of turbulence that can reach up to five times the height of the mountains and extend for hundreds of miles, depending on wind strength. Planning flight routes around mountainous areas or regions prone to this type of turbulence can prevent encountering it.
4. Weather-related turbulence: Weather-related turbulence occurs in the presence of cumulonimbus clouds, commonly known as thunderclouds. These large, white, puffy clouds can grow in width and height, often surpassing the average cruising altitude of airliners. Pilots fly around these clouds to avoid weather-related turbulence or delay take-offs and landings if they directly impact the airport.

Regarding Flight SQ321, the incident involved clear-air turbulence, which can be challenging to anticipate as it does not appear on the weather radar in the flight deck. The question is whether incidents caused by turbulence will increase and if other airlines will follow WN's lead.

Scientists at the University of Toulouse have predicted increased clear-air turbulence in the Northern Hemisphere as the climate changes. The study's findings, which indicate the risks of global warming to aviation, were published in the Journal of Geophysical Research: Atmospheres.

Climate experts utilized 11 climate models and 20 computer simulations to anticipate changes in clear-air turbulence under various scenarios of temperature rises ranging from 1 to 4 degrees Celsius.

According to the studies, turbulence would increase over most Northern Hemisphere locations influenced by the jet stream, particularly in North Africa, East Asia, and the Middle East. Turbulence increases with each one-degree increase in temperature.

What are the most turbulent routes in the world? Find out in our in-depth analysis.