What is aircraft turbulence and how common is it? | Explainer

One passenger dies in turbulence on Singapore Airlines flight, raising questions about safety and climate change impact.

One passenger died of a suspected heart attack and 30 others were injured after a Singapore Airlines flight from London to Singapore hit severe turbulence on May 21, forcing the Boeing 777-300ER jet to divert to Bangkok, authorities said.

Turbulence or pockets of disturbed air can have many causes, most obviously the unstable weather patterns that trigger storms, according to an industry briefing by planemaker Airbus. The resulting water particles can be detected by weather radar.

Singapore Airlines did not immediately say what type of turbulence was involved. Tracking service FlightRadar24 said there were storms — some severe — in the area at the time.

Known by its abbreviation CAT, this is a sudden and severe swirl that causes violent buffeting of a plane even where there are no clouds, according to the Federal Aviation Administration. Such invisible pockets of air can appear without warning, and are hard to predict.

Mark Prosser of the University of Reading said the May 21 event most likely involved convective or storm-related turbulence, but stressed it was too early to be certain. An investigation has been launched and experts stress aircraft accidents typically involve a combination of factors.

Turbulence-related incidents are common, according to a 2021 study by the U.S. National Transportation Safety Board. From 2009 through 2018, it found that turbulence accounted for more than a third of reported events and most resulted in one or more serious injuries, but no aircraft damage. Yet fatal turbulence in air travel remains extremely rare.

"It is a very unusual and rare event. As far as I can tell it is over 25 years since a passenger was killed by commercial airliner turbulence," said Paul Hayes, director of safety at UK-based aviation data group Cirium Ascend.