Unprecedented increased in turbulence affecting high capacity Australian aircrafts occurred over the recent summer months, The Australian Transport Safety Bureau (ATSB) warned.

According to the recent observation conducted by ATBS, the odd turbulence were weather-related occurrences that could affect safety of cabin passengers.

"We are seeing a doubling of turbulence and windshear events in passenger operations. And some of those events are affecting the safety of those in the cabin." said Dr Stuart Godley, head of the ATSB's Aviation Safety Research team, in a statement.

The ATSB observed that from the months of October to December of 2013, turbulence and windshear events increased significantly. Odd turbulence events for these months were above the 5-year historical average, doubling in the span of just three months.

"Because they're weather-related, these events are cyclical. We're used to seeing more of them in the summer, but this increase is unprecedented. We're especially concerned because there is a correlation between these events and cabin safety issues, especially cabin injuries due to turbulence," Dr Godley explained.

ATSB warned that turbulence is the leading cause of in-flight injuries for passengers as well as cabin crews.

ATSB described turbulence as the irregular movement of air. Chances are, turbulence are invisible to the eyes.

"When air masses with different speeds, direction or temperatures meet each other, turbulence is likely to occur. While turbulence is normal and occurs frequently, it can be dangerous," ATSB explained through their web site.

Ninety-nine per cent of passengers remained unharmed during ordinary turbulence occurrences.

But unique episodes of turbulence can make the ride bumpier. And as turbulence occurred without warning, passengers and cabin crews can be thrown around the plane - this is the second most usual type of head injury on aircraft.

"For the five-year period 2009 to 2013, there were 677 turbulence occurrences on flights in, to or from Australia that were reported to the ATSB, with 197 minor injuries and 2 serious injuries to passengers and cabin crew. The United States Federal Aviation Administration (FAA) estimates that the cost to the worldwide aviation industry of turbulence injuries is over US$100 million annually, and growing," ATSB said.