Understanding Clear Air Turbulence

Clear blue, cloudless skies do not always translate into pleasurably smooth airplane rides that will lull passengers to sleep. If your airplane is cruising over 15,000 feet you may still be susceptible to CAT, an acronym which stands for Clear Air Turbulence. If this is the case, watch for the seat belt sign to glow and listen to the commander's recommendation to buckle up. You may encounter some rough bumps.

Contrary to its name, it is important to point out that clear air turbulence does not always show up in friendly, clear skies. Indeed, only 75 percent of CAT cases take place in clear weather, with the remaining amount often occurring in cirrus clouds and hazy layers, explains Shari Stamford Krause  in the book ''Aircraft Safety: Accident Investigations, Analyses and Applications''.

This sky foe has been responsible in the past for several injuries to passengers and flight attendants. And perhaps what makes this form of turbulence  more worrisome, is its insidious nature since CAT is invisible (radars cannot detect it) and can take place without warning. The only way to be aware of this form of turbulence in advance is when pilots in aircrafts ahead of yours report turbulence ahead. But if you are on one of the first planes to pass the area, such as an early morning flight, you may be the first to  have the exclusive pleasure of experiencing it. 

Once encountered, however the pilot may take steps to make the flight more comfortable. He may reduce the speed of the aircraft in order to minimize the risk for structural damage if the CAT is severe.  Reducing speed can also significantly reduce the level of  vibration  in the aircraft making  the instruments easier to read. The pilot may also ask air traffic control permission to climb to a higher altitude or descend in order to escape  the turbulence. 

The seat belt light will be turned on as soon as the presence of CAT is acknowledged. This often involves the cabin crew which will need to halt the serving of hot beverages and food. At this point, it is the passenger's responsibility to stay strapped in. This is not a good time to ignore the seat belt sign and pilot's warnings and go for a potty break or on a stroll to stretch out. Rather, patiently, wait to fly through the rough air and await for the seat belt sign to turn off. A seat belt may prevent you from bouncing off the ceiling in severe cases.

As troublesome as clear air turbulence sounds, the good news is that severe cases are uncommon. The wings may be flexing up and down, but they are purposely made that way to withstand turbulence. It may be comforting to learn that the wing tips of large aircraft are capable of moving twenty feet or more both up and down without getting damaged. Should they have been rigid, the would have been more likely to break up.

 The choice of your seat can really make a difference between some mild bumps and a roller coaster ride. Generally, turbulence is felt at its mildest in the flight deck and is generally more severe in the seats located near the rear. If you are prone to getting motion sick, then avoid such seats.

CAT may  sound like risky business but it is more likely to cause your drinks to spill rather than anything else. The cabin crew may be annoyed that food service may be delayed and there may be more cleaning involved. The captain and crew are used to turbulence and will take all steps to make your ride more comfortable.  They will not be struggling with the controls with a sweaty forehead as many fearful fliers may imagine. Rather, they may just be annoyed if their cup of coffee will spill.  So if you experience CAT,  just wear your seat belt and relax, your plane is made to withstand much more stress than ordinary turbulence.