What is cloud suck, the phenomenon behind the paraglider incident?

A Chinese paraglider has drawn attention after surviving a rare and dangerous flight incident over the Qilian Mountains, where he was unexpectedly lifted to an altitude of 8,598 meters by a powerful cloud updraft without oxygen support.

The paraglider, whose face was fully exposed and body covered in ice crystals, managed to stay conscious and in control throughout the ordeal. After eventually landing safely, he described suffering from oxygen deprivation and freezing hands due to prolonged exposure at high altitude.

Why did the incident happen?

Aviation expert Wang Yanan told China Media Group that the phenomenon that caused the incident is known as cloud suck, and it occurs when a paraglider is drawn into rapidly rising air currents near cumulonimbus clouds. These updrafts can boost the flyer's altitude dramatically – but dangerously – due to their intensity and unpredictability.

"This kind of ascent carries serious risks," Wang said. "Once inside the cloud, the pilot may face extreme cold, hypoxia, turbulence or even lightning. At very high altitudes, these dangers multiply, making cloud suck potentially fatal."

Risk of collision with commercial aircraft

Wang also warned that reaching altitudes over 8,000 meters brings paragliders close to the cruising level of commercial airliners.

"If the flight zone overlaps with civil aviation routes, the paraglider could suddenly appear in regulated airspace, posing a safety hazard," he noted.

In China, paraglider flights are strictly regulated and require advance clearance from aviation authorities. However, the use of cloud suck to gain altitude introduces greater unpredictability, making it a discouraged practice within the sport.

Zhao Jingwu, associate professor at the Law School of Beihang University, explained further.

"Passenger planes travel at very high speeds. A small object like a paraglider is extremely difficult to detect or avoid, especially as onboard radar systems may not pick it up. Any collision at that altitude would be catastrophic," Zhao said.

China's controlled airspace system

China operates a unified flight control system, dividing its airspace into various classes, each with different requirements. Class A airspace – above 6,000 meters – is the most tightly controlled and is typically reserved for long-distance commercial flights. All aircraft in this zone must follow instrument flight rules and receive air traffic control services.

Other controlled zones (Classes B to E) also require varying levels of oversight. In contrast, non-controlled areas like Class G and W allow more freedom for general aviation activities – but pilots are still obligated to follow safety regulations and coordinate with authorities to prevent airspace violations.

This incident highlights both the dramatic possibilities and the serious dangers involved in extreme paragliding. While the pilot in this case survived, experts caution against attempting such high-risk maneuvers – especially without proper oxygen equipment and airspace clearance.

(Cover image: The Chinese paraglider during his flight, May 24, 2025. /CMG)