Severe turbulence on a Singapore Airlines flight resulted in one death—and injuries to 71 others. It was caused by something called Clear Air Turbulence. It is going to become extremely frequent thanks to global warming—which will affect almost every aspect of airline travel.
So what exactly happened to the Singapore flight?
A Singapore Airlines flight—from London to Singapore—hit heavy turbulence over the Indian Ocean. The plane dropped 6,000 feet (around 1,800 metres) within three minutes—during meal service, when many were not wearing a seatbelt. It fell from 37,000 feet above sea level—to 31,000.
One person died of a heart attack—and 71 others were injured. Seven were severely injured, and 23 passengers and nine crew members had moderate injuries. According to one passenger: “Every single cabin crew person I saw was injured in some way or another, maybe with a gash on their head.”
So they flew into a storm?
Nope, the plane encountered something called ‘clear air turbulence’.
About ‘turbulence’: First, let’s clarify what it means. ‘Turbulence’ is a fancy word for anything that disrupts air flow (as you might a wave). Closer to the ground, it can be caused by a large land mass. But when you’re up in the air, it is caused by “the meeting of air at different temperatures, pressure or velocity, where different wind patterns collide.” That’s why you get thrown around:
[T]he aircraft is in fact following the direction of the turbulent air which may be up or down or side to side. It often causes a quick drop in altitude which you feel by being lifted from your seat, or even a climb which presses you into your seat.
So, yes, thunderstorms can also cause turbulence. But as with large mountains, this kind can be mapped by meteorological services. So pilots know where they are and—for the most part—what to expect. But that’s not true of CAT—or Clear Air Turbulence—which is the kind encountered by that Singapore Airlines flight.
Trouble you can’t see: Unfortunately, CAT is invisible—so the pilot typically doesn’t have any warning. Their presence has to be inferred by looking at other factors—edges of jet streams, storms, or terrain:
Even then, these ‘pockets’ can be impossible to avoid:
Clear-air turbulence is invisible “not only to the naked eye but also to the onboard weather radar,” says Paul Williams, professor of atmospheric science… “It is one of the few weather phenomena that render the radar completely useless. Often, the first indication that there’s any clear-air turbulence on a flight path is when the aircraft is already flying through it.”
Really? Sounds scary and dangerous…
Don’t worry, clear air turbulence very rarely causes serious injuries. The last confirmed death caused by turbulence happened in 1997—on board a United Airlines flight from Tokyo to Honolulu. And here’s why:
One: Pilots have become very good at sharing information on CAT they encounter—which goes into a database: “At present, more than 2000 daily aircraft from 23 airlines provide data to help forecast air turbulence patterns, mapping 380 million annual observations a year.”
Two: Airplanes have become much, much sturdier:
In fact, aircraft are engineered to take a remarkable amount of stresses and strains, and a huge safety margin is built into the designs so that even very severe turbulence will not exceed the design limits of the aircraft. For example, the level of turbulence required to bend a wing spar is something even most pilots will not experience in a lifetime of travelling.
Also, turbulence is highly unlikely to cause serious harm as long as passengers are strapped into their seats.
Be like Swiss cheese: Airlines are guided by what is called a ‘Swiss cheese model’. Think of various safety systems as slices of cheese—each with its own set of holes (weaknesses). But the other slices serve to block these holes—so nothing bad happens… unless all the holes line up, causing an accident.
Darren Ansell in The Conversation points to a 1966 crash caused by turbulence—when a Boeing 707 crashed due to turbulence. Cheese slice failure #1: The pilot diverted from the flight plan—which is a safeguard—to show his passengers Mount Fuji. Cheese slice failure #2: The aircraft was not designed to handle the 140 mph wind off the mountain—which ripped the tail apart. The very good news: Such failures are near-impossible today.
So what’s the deal with climate change?
Today, aircrafts encounter some form of turbulence 790 times a year—that’s once every 11 hours. Researchers say such events over the North Atlantic have increased by 55% between 1979 and 2020. That’s because wind shear—or sudden changes in wind speed or direction—has increased by 15%:
This results in more unstable air at play within the jet streams that move across the U.S., often at the same altitudes where commercial and private aircraft commonly travel–and the researchers noted that the busy transatlantic flight corridor will be similarly affected.
And some predict rising CO2 levels will make them 2-5X more frequent—so much so that there will be at least five serious cases a day.
Not just turbulence: Aviation experts warn that climate change is likely to impact airline travel in a multitude of ways—requiring a rehaul of the industry. These include:
One: Climate change is shifting the jet stream—which will affect travel times—especially in the Northern Hemisphere. It will likely make west-bound flights longer—and speed up east-bound flights.
Two: Global warming turbocharges thunderstorms—making them more frequent and powerful—which in turn will create greater turbulence:
So, the storms are more energised, the wind shears more dramatic, and the jet streams more unstable. Lightning strikes or static discharges… are going to become more common, too–they’re expected to increase by 50% in the U.S. by the end of the century, with each 1 degree Celsius of warming producing about 12% more strikes.
Three: Extreme heat will cause flight delays, cancellations—and far greater weight restrictions:
Warm weather makes the air less dense, requiring planes to move faster to get off the ground. On extremely hot days, airlines often restrict a flight’s weight by cutting the number of passengers or restricting the plane’s cargo load. On rare occasions, extreme heat can lead airlines to cancel flights altogether… A 2017 study in the journal Climatic Change found that up to 30% of flights departing at the hottest part of the day may face weight restrictions in the coming decades.
Four: Coastal airports are in danger of going underwater due to rising sea levels. If not, at the very least, their runways will be at risk from frequent coastal flooding—which will cause closures and damage.
The bottomline: The New York Times notes:
Air travel accounts for about 4 percent of human-induced global warming, and the United Nations warns that airplane emissions are set to triple by 2050. Planes are becoming more efficient, but our appetite for air travel is outpacing the industry’s environmental gains.
On the bright side: maybe we will now take fewer flights. 🤷🏽
Reading list
Associated Press details what happened on the Singapore Airlines flight. The Conversation has the best explainer on turbulence while the New Zealand Herald looks at what causes clear air turbulence. Fortune (paywall) and Time Magazine explore the impact of climate change on air travel.
