Tuesday, 11 December 2007 20:59
Hello Capt Lim,
So from your experience, how often do severe air turbulence occur? And on an average, how long will the turbulence last? Would you give me some more details?
From my experience, I do encounter air turbulence almost daily during the course of my normal flying but they are classified as light to medium in nature and nothing to worry about. Severe air turbulence can arise when one is trapped inadvertently inside a severe thunderstorm. This may be because the pilot was trying to navigate through some line squalls and the weather radar was not very effective or the aircraft may be flying in the vicinity of micro-burst activities. (See my FAQ on Windshear)
Severe air turbulence can also be quite prevalent in jet streams found near the frontal systems. In fact, they are more likely to be associated with clear air turbulence (for forecast of clear air turbulence (CAT) risks in the USA, please click here ). CAT is something you cannot see but know that they are present because of their proximity to the jet streams. Such severe air turbulence is predictable and often shown in the pilot's weather chart. To avoid severe air turbulence, pilots often request for a higher or lower level or to a re-routing.
Sometimes such requests may not be possible due to other air traffic and you have to bear with them for a while. Always remember to have your seat belts securely fastened.
The pilots would take the necessary precautions like reducing the airspeed to comply with the structural limitation and warning everyone to be securely fastened onto their seats.
It is difficult to say how long a light to moderate turbulence will last because it would depend on your journey. It can be as short as 5 minutes to as long an hour or so. If the track to your destination is smack inside the area of clear air turbulence, then you may be in for a long and rough ride. Otherwise the pilots would endeavor to avoid it because it can be quite uncomfortable to everyone inside the aircraft.
Classification of turbulence starts from Category 0 (None) to Category 6 (Extreme). Severe turbulence is Category 5. So how long does severe air turbulence (Cat 5) last? I suppose no sane pilot would wish to encounter one of that severity for he would make all effort to avoid it. If there is one, it would be for a short duration only for every possible means would be made to steer clear of them!