Understanding Turbulence: A Pilot explains.

I have a little confession to make. 

I am not a huge fan of flying. 

As excited as I am about the prospect of traveling around the world, turbulence makes me nervous. 

Flying for me is a means from getting from home to my next destination, but it’s not something I enjoy at all. The moment it gets bumpy, I secretly turn into a basket case (inside). 

With some long distance flights ahead in our 2018 travel plans I’ve decided that this is the year I will start conquering my fears when it comes to turbulence. The first step for me was to get more information. 

What exactly is turbulence?

Who best but a pilot to answer this question!  

Let me introduce to you Sales Wick, senior First Officer and Instructor on Boeing 777 at Swiss.

Sales has been flying for Swiss for the past 8 years and currently flies long haul to places like Los Angeles and Hong Kong. 

I put a call out to the Simple Family Travel Instagram community last year asking questions about turbulence and from the responses it would seem I am not alone with my fears.  Read on to learn all about what turbulence is, how it’s caused, and what you can do to stay safe while you’re experiencing it. (Part 2 can be found here.)

 

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SFT: What exactly is turbulence?

SALES: You can imagine turbulence, just like waves on the sea. It is a sudden change in airflow, which can be caused by a number of factors.

The most common cause is turbulent air in the atmosphere. It is created in the mixing zone of different air masses. A common term for this would be our global weather systems.

Another type is thermal turbulence. It is created by hot rising air usually from cumulonimbus clouds and therefore more common in warmer areas or with seasonal variation.

There is also mechanical turbulence, which is caused when moving air masses get deflected by the landscape like mountains or tall buildings. They will distort the air flow in the sky above them, just like water of a river the flows through rapids or reaches a big stone in its path.

But airplanes also can create turbulence. Just like a boat in the water will cause waves, the wings of an airplane cause wake turbulence as it flies. This cone of disturbed air can affect planes flying behind or below. The bigger the plane and its wings, the greater the wake turbulence.

We pilots, together with the air traffic controller and our ground staff do our outmost to avoid any kind of turbulent areas. But even when we do run into it, the risks are low as modern airplanes are built to withstand even severe turbulence.

As we just learned turbulence can have different kind of causes. Some are more predictable others can occur in clear air and without any prior indication. This is why you should always wear your seatbelt when seated.

  Some impressive cumulonimbus clouds to our right. You can see that the right clouds is still in its building stage, thus not yet fully grown while the one to the left is already in its dissipating stage indicated by the less clear shaped contours and the anvil top.

Some impressive cumulonimbus clouds to our right. You can see that the right clouds is still in its building stage, thus not yet fully grown while the one to the left is already in its dissipating stage indicated by the less clear shaped contours and the anvil top.

 

SFT: Can you predict turbulence and do you try to avoid it?

SALES: We have a variety of methods and systems to predict turbulence, not only while planning a flight, but also when airborne. Based on this information and our experience, we will avoid these areas as well as we can. This will not always be possible especially on a twelve-hour flight and when crossing areas which are prone for disturbed air masses.

Our flight planning documents, we study during the pre-flight phase, offer several maps that indicate turbulence. This information are forecasts calculated by computer models and meteorologist, we will take them as a reference for our awareness. While airborne we will receive turbulence reports from other pilots through our ground staff as well as the air traffic controller. These information, together with our experience, the forecasts we received earlier will all play into our decision regarding our flight path.

 

  Before each and every flight we get a briefing package containing the flight plan (our route), information about the airport enroute and at our destination as well as a weather briefing. This document is called Significant Weather Chart (SWC) and shows some weather that could affect us during the flight. On this flight from Zurich to Hongkong (red line is our route) we got to cross a jetstream (area 1) that was accompanied with a zone of turbulent air (doted line to the left with the number 5, you can see in the legend that this area is vertically located between 300 and 430, meaning the flight level. Just add two zeros and you will get the altitude in feet.) further on in the journey, somewhere over India we will be flying through a zone of isolated embedded cumulunimbus (meaning convective clouds that are immersed within other clouds). This is a prediction based on forecasts, of course this usually shifts slightly during a period of this 12 hours flight but gives is a good idea of whats ahead.

Before each and every flight we get a briefing package containing the flight plan (our route), information about the airport enroute and at our destination as well as a weather briefing. This document is called Significant Weather Chart (SWC) and shows some weather that could affect us during the flight. On this flight from Zurich to Hongkong (red line is our route) we got to cross a jetstream (area 1) that was accompanied with a zone of turbulent air (doted line to the left with the number 5, you can see in the legend that this area is vertically located between 300 and 430, meaning the flight level. Just add two zeros and you will get the altitude in feet.) further on in the journey, somewhere over India we will be flying through a zone of isolated embedded cumulunimbus (meaning convective clouds that are immersed within other clouds). This is a prediction based on forecasts, of course this usually shifts slightly during a period of this 12 hours flight but gives is a good idea of whats ahead.

 

SFT:  Are there certain routes that are more prone to turbulence than others?

SALES: There certainly are. But as explained earlier there are different kind of factors causing turbulence. Some are caused by seasonal changes in the weather and others by geographic location. 

Especially during the summer days, the air close to the ground tends to be more distorted due to the heat and thus creating thermal movement of the air. Flying over vast area of water (like the Atlantic Ocean) offers a great playground for weather systems to evolve and air masses to move. That’s mainly were jet streams are prominent and the air on its edges tends to be disturbed. But also while flying above high mountains you might experience some turbulent air, as the wind get deflected by the terrain beneath.

And the longer the flight, the higher the chance that you will eventually fly over or through an area more prone to turbulence.

  Our on-board weather radar system is our third eye. It can detect water vapour in the atmosphere and thus indicate convective weather along our flight route. Here you can see our planned route to the right (solid magenta line) while we are circumnavigating the weather cell to the north. Soon we will need to take a right turn to get in between the smaller cells ahead. Keep in mind that one white circle indicated 40Nm (approx. 70km).

Our on-board weather radar system is our third eye. It can detect water vapour in the atmosphere and thus indicate convective weather along our flight route. Here you can see our planned route to the right (solid magenta line) while we are circumnavigating the weather cell to the north. Soon we will need to take a right turn to get in between the smaller cells ahead. Keep in mind that one white circle indicated 40Nm (approx. 70km).

  And this is what you would see looking out of the window. Can you recognize some of the weather depicted on the radar?

And this is what you would see looking out of the window. Can you recognize some of the weather depicted on the radar?

 

SFT: Are pilots ever scared or nervous during turbulence? (Question from a 6 year old)

SALES: Well, you can imagine, that I as a pilot prefer a smooth ride just as everybody else on board. If we get into an area of turbulence, we usually know this in advance and we also know what it feels like. I am used to this feeling so much that this doesn’t cause me to become nervous or even scared.

 

SFT: Is there a certain place to sit in the plane that experiences fewer bumps?

SALES: Turbulence or disturbed air masses will cause some kind of movement of an airplane. When booking seats, aim for ones closest to the wings. This area will be the smoothest during turbulence as you are sitting close to the centre of gravity. As every movement of the aircraft will happen around this point, sitting close to it, will make you experience less deflection.

  So-called lenticularis clouds are a good indicator for strong winds. Their upper shape is carved by the winds reaching speeds of up to 300km/h or more.

So-called lenticularis clouds are a good indicator for strong winds. Their upper shape is carved by the winds reaching speeds of up to 300km/h or more.

 

SFT: Do larger planes have less turbulence?

SALES: As mentioned above, turbulence are disturbed air masses. Just like waves on the sea they will make any object immersed in it experience some kind of movement. The bigger/heavier an object is, the less are the effects. Just like with a small boat compared to a big vessel.

 

SFT: What makes turbulence more severe? How can I calm my nerves during serve turbulence and not worry that the plane is going to crash or fall apart?

SALES: Severe turbulence is very rare and several factors can play into its severity.

Always make sure that your seatbelt is securely fastened whenever seated.

These kind of turbulences are reported by other pilots and usually restricted to a confined area. Based on these information we will alter our route and avoid this area.

  A lightening in the sky. We are enjoying a smooth ride over the Mediterranean coast of Croatia as we are watching the spectacular show of mother earth from a safe distance.

A lightening in the sky. We are enjoying a smooth ride over the Mediterranean coast of Croatia as we are watching the spectacular show of mother earth from a safe distance.

 

SFT:  How much turbulence can a plane experience without the wings breaking off?

SALES: Modern aircraft are built to withstand even severe turbulence. And there has been no aircraft accident within the past 40 years where turbulence was the root cause. 

We would need to ask a structural engineer regarding the maximum amount that an airplane can withstand. But there is a very rigid certification process for a new airplane that takes its structure way beyond stresses it will experience during its operation.

 

SFT: Has a plane ever crashed because of turbulence?

SALES: Back in the golden ages of aviation - a few decades ago - there were a series of accidents of airplanes breaking-up in mid-air due to mechanical failure or stress. As we all know technology, not only in aviation, has taken some massive leaps forwards since then. During the certification process of every newly designed airplane the wings, as well as the airplane structure in general will be tested for all kind of mechanical stresses and need to pass them with safety margins of up to 2.5 times the required loads.

 

SFT: Are there other reasons for a bumpy flight?

SALES: No, turbulence is the main reason for a bumpy flight.

  An impressive thunderstorm with lightening over the vast desert between Los Angeles and Las Vegas on a full moon night. What a sight.

An impressive thunderstorm with lightening over the vast desert between Los Angeles and Las Vegas on a full moon night. What a sight.

 

A huge thanks to Sales for taking the time to answer all of these questions in such great detail.  I feel like I am finally one step closer to being able to relax when turbulence strikes again. 

Come back next Monday for the second instalment, where Sales will answer more general flying questions including his top tips for jet lag. 

You can follow along Sales’ inflight journey at his wonderful informing Instagram account @sky_trotter where he not only shares his beautiful photographs (he is an extremely talented Photographer!) but also insights into his flights through his Instagram Stories. You can also find more of his stories on his blog Beyond Clouds