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| Image: AP Photo/Mark Baker |
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Unexpected severe turbulence injured crew and passengers on a Qantas Boeing 737 during descent at Brisbane on May 4 2024.
The subsequent Australian Transport Safety Bureau investigation suggested the severity of the turbulence caught the captain by surprise.
This is not an isolated event. Thunderstorms featuring severe wind gusts such as violent updrafts and downbursts are hazardous to aircraft. Downbursts in particular have been known to cause many serious accidents.
Our new research suggests global warming is increasing the frequency and intensity of wind gusts from thunderstorm “downbursts”, with serious consequences for air travel.
We used machine learning techniques to identify the climate drivers causing more thunderstorm downbursts. Increased heat and moisture over eastern Australia turned out to be the key ingredients.
The findings suggest air safety authorities and airlines in eastern Australia must be more vigilant during takeoff and landing in a warming world.
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| The weather radar system on a 737 jet plane can detect a microburst just before it causes heavy turbulence. Qantas, annotated by the ATSB |
Warm, moist air spells trouble for planes
Global warming increases the amount of water vapour in the lower atmosphere. That’s because 1°C of warming allows the atmosphere to hold 7% more water vapour.
The extra moisture typically comes from adjacent warmer seas. It evaporates from the surface of the ocean and feeds clouds.
Increased heat and water vapour fuels stronger thunderstorms. So climate change is expected to increase thunderstorm activity over eastern Australia.
For aircraft, the main problem with thunderstorms is the risk of hazardous, rapid changes in wind strength and direction at low levels.
Small yet powerful
Small downbursts, several kilometres wide, are especially dangerous. These “microbursts” can cause abrupt changes in wind gust speed and direction, creating turbulence that suddenly moves the plane in all directions, both horizontally and vertically.
Brisbane airport recorded a microburst wind gust at 157km/h in November 2016. Three planes on the tarmac were extensively damaged.
On descent or ascent, aircraft encountering microbursts can experience sudden, unexpected losses or gains in altitude. This has caused numerous aircraft accidents in the past. Microbursts will become increasingly problematic in a warming climate.
Delta Flight 191 is the most famous aviation accident caused by a microburst.
Smithsonian Channel Aviation Nation
Microburst analysis and prediction
Microbursts are very difficult to predict, because they are so small. So we used machine learning to identify the environmental factors most conducive to the formation of microbursts and associated severe wind gusts.
We accessed observational data from the Bureau of Meteorology’s extensive archives. Then we applied eight different machine learning techniques to find the one that worked best.
Machine learning is a field of artificial intelligence using algorithms to find patterns and make predictions from data without explicit programming.
We found atmospheric conditions in eastern Australia are increasingly favouring the development of stronger, more frequent thunderstorm microbursts.
We investigated a microburst outbreak from a storm front in 2018. It produced severe wind gusts at six NSW regional airports: Bourke, Walgett, Coonamble, Moree, Narrabri and Gunnedah.
Regional airports often use small aircraft, and planes with 4–50 seats are more vulnerable to the strong gusts spawned by thunderstorm microbursts.
Widespread consequences
Our regional case study identified the weather patterns that create severe thunderstorms in eastern Australia during warmer months.
High cloud water content creates a downward force in clouds that induces a descending air current. When the heavier air hits the ground, gusts spray out in all directions.
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| A small yet powerful downburst can deflect a plane’s descent path. Mehmood, K., et al (2023) Fluids, CC BY |
These wind gusts endanger aircraft during takeoff and landing. Rapid wind shifts from tail winds to head winds can dangerously alter altitude.
Our analysis highlights elevated aviation risks from thunderstorm microbursts across eastern Australia. Smaller aircraft at inland regional airports are especially vulnerable. But these microbursts must also be monitored by major airports like Sydney and Brisbane.
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| Planes at Sydney Airport are most at risk during October to March. AAP Image/Dean Lewins |
Beware of heightened microburst activity
Flying remains one of the safest travel modes, with an accident rate of just 1.13 per million flights.
But global passenger numbers have grown dramatically—meaning even a small increase in risk could affect many travellers.
Previous climate risk research has focused on high-altitude issues like clear air turbulence and jet stream instability. Far less has looked at low-level risks during takeoff and landing.
Our research is among the first to detail heightened thunderstorm microburst risks, driven by climate change. Airlines and safety authorities must prepare for more frequent and intense turbulence, especially over eastern Australia, in our ongoing warming climate.
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