It is just turbulence, nothing to worry about!

Air movements could cause an uncomfortable ride but are common during flights. Jimmy Wanjala Recently, I heard a friend of mine complain that her flight to Eldoret was very shaky. She even went ahead to place the blame on the pilots of that flight. She is not the only one to complain to me that whenever they fly with a certain airline or a certain type of airplane, they experience a very bumpy ride. I bet you too have wondered what goes on especially on the descent - the last few minutes just before touchdown. Neither the pilot nor the airline is to blame. Blame it on the turbulence… An aircraft generates lift through the interaction of the wing and the air. Depending on the location, time of day and height, each parcel of air exhibits different characteristics. Unless you are trained to make an observation and decipher, it is very difficult to point out what conditions one might experience as you fly from one parcel of air to another. Although the main culprit of a bumpy flight is always the turbulence, what causes the turbulence varies and as a pilot this is covered in a unit we study called Meteorology. Depending on the cause of the turbulence, a pilot may be able to detect and avoid before flying into it. In some instances it catches you completely offguard and the only option left is to continue flying and hope the condition will get better, or change course and height or both to get away from the turbulence. This decision is mainly influenced by the intensity of the turbulence. Starting from the least dangerous to most detrimental to the safety of the aircraft, we have light turbulence; this one is the baby. Most passengers hardly notice this one as there is very little change in attitude. Some people even find this kind of turbulence enjoyable (by some people I mean myself; it stimulates my mind to optimum levels keeping me vigilant in flight). When light turbulence changes to moderate turbulence, that is when most people will start taking note of what is happening. You will notice at this point that the seat belt signs have been turned on by the pilots and those passengers who had their belts off are buckling them up. The aircraft shakes considerably and some people might find it uncomfortable. Accidents like hot drink spillage could occur and that is why it is advisable at this point to close and stow away your laptop and put a lid on your beverage. Service from the cabin crew might continue but you will notice they will not offer hot beverages for safety purposes. But things start getting interesting when the turbulence moves a scale up and graduates to more severe one. Anything loose at this point is flying and if you are caught standing abruptly you could be thrown off balance and injure yourself. At this point the pilot or the cabin crew might make a public announcement and request the passengers to take their seat and fasten their seatbelts. If this happens and you are away from your seat do not fight to get back. Just take the nearest seat and buckle up until the pilots navigate the aircraft away from the turbulence; I can bet you that is what they will be doing because even the best pilot might fight it hard to maintain control of the aircraft in severe turbulence. The last class is one that we try to avoid at all cost. We might even divert and land at a completely different destination if that what it takes to stay away. Why? Because if you get caught in this kind of turbulence, you could easily lose control of the aircraft and crash or you could exceed the acceptable levels of stresses and cause structural damage to the aircraft. Pieces could break off the aircraft, rendering it unable to fly or as a write-off once you land. Either way, none is good. This is what we refer to as extreme turbulence. The last two are commonly encountered in storms. In Kenya, we encounter thunderstorms which we can tell by observing a towering type of cloud. With intense rain from the cumulonimbus cloud especially close to the ground level, windshear could occur. This is a phenomenon that causes a gush of wind to flow downwards and thereafter outwards as it hits the ground, same way water spreads when you attempt to wash a spoon. The sudden change in wind direction could cause eddies that make an aircraft shake violently. On a hot and clear day, especially at midday you will notice light to moderate turbulence. These ones are cause by the convectional currents. As the sunrays hit and warm the earth, the earth is return warms up the air adjacent to it. As we all know, warm air is less dense than cold air above it; the warm air will rise and the cooler air descend. This mechanical exchange of place will cause circular motion of air and in turn, if an aircraft flies in this parcel of air, the disturbance will be passed to the airframe as turbulence. This is why no matter what, landing in Nairobi and especially in January, will always be bumpy and there is nothing pilots can do. Sometimes the circular motion could occur on a beautiful chilly morning. The sun is still rising and the temperatures are low. In this case you may want to look out for mountains. As we said before, cold air is dense and this makes it resist change. We refer to this parcel of air as stable. When this parcel of air moves horizontally as wind and it encounters an obstacle like a mountain, it will be forced to momentarily climb and as soon as it crosses the obstacle, it descends and in so doing continue flowing in circular motion. This could cause turbulence at any flight levels as long as you are flying on the downwind side of a mountain. As you have seen, the causes of turbulence and therefore bumpy rides are many. But as you fly to other places, causes change but we can all agree that the details are for pilots, but it helps to know and appreciate that the pilots do the best they can and sometimes they don’t have control over it. And that is why you should always have your seat belt fastened and seated at all times, whether the seat belts signs are on or not. Better safe than sorry!