Turbulence was so bad on a flight to Hong Kong that 39 people were injured.

A Thai Airways Airbus A380 was carrying 500 passengers when it hit severe turbulence on Friday morning. The flight had left from Bangkok. According to Kenny Kung, the airline's sales manager, both passengers and crew members suffered from minor injuries as the plane was coming in for a landing at Hong Kong's Chek Lap Kok airport shortly after midday.  Those that were hurt had to be transported to three area hospitals, Telegraph Travel reports.

That wasn’t the only incident in which people were hurt due to turbulence. A Hong Kong Airlines flight from Phuket his sudden turbulence as it approached the Hong Kong Airport. The plane landed safely but three passengers and three flight attendants were hurt in the incident. That plane was carrying 110 passengers and seven crew members. The six injured people have been released from the hospital.

There have been instances of unsettled weather around Hong Kong as Tropical Storm Kong-rey passes nearby.

Turbulence is the most common cause of injury involved in air travel but extreme turbulence is a rare occurrence.

Steve Allright, a British Airways pilot discussed turbulence on planes with Telegraph Travel.

"Flight crews around the world share a common classification of turbulence: light, moderate and severe," he said. "Severe turbulence is extremely rare. In a flying career of over 10,000 hours, I have experienced severe turbulence for about five minutes in total. It is extremely uncomfortable but not dangerous. The aircraft may be deviating in altitude by up to 100 feet (30 metres) or so, up as well as down, but nothing like the thousands of feet you hear some people talking about when it comes to turbulence."