I am often asked by laymen, “What airplane do you drive?” As pilots, we routinely refer to ourselves as “drivers.” So, what better segue is there than to address the “rough road ahead” during the winter months? This month, I will touch on atmospheric turbulence.
As always, a disclaimer or two — I am a pilot, not a meteorologist, and turbulence can happen anytime. As a non-meteorologist, I share only a limited amount of knowledge with you. My primary goal is to motivate you to learn more about turbulence and to remind you of the available resources for avoiding the painful experience of turbulence, which comes in a variety of forms occurring in any season.
My focus here is high altitude, non-convective turbulence. This article reeks of the jet stream, which as you know, is much more active in the winter months due to the greater ranges in temperatures between cold and warm air masses.
Turbulence is where you find it
Often, Air Traffic Control and the Aviation Weather Center will begin to issue weather products related to turbulence as a result of PIREPS. Not always, but sometimes, we are test vessels for what’s out there. We are the ones who start all the trouble.
As a pilot, the types of weather products you must be aware of are:
1) Center Weather Advisories (CWA). These are products initiated by Air Traffic Control (usually because of PIREPS) that advertise turbulent conditions. CWA’s are warnings that meet or approach national in-flight advisory criteria. Simply, they are a lesser version of SIGMETS/AIRMETS. Said yet another way, CWA’s can be thought of as precursors to SIGMETS/AIRMETS.
2) SIGMETS/AIRMETS: I’ll spare you of the definition of these two weather products. Suffice it to say, you should already know what each of these is and their differences.
Before every flight you should be intimately aware of the existence of these weather products. Fortunately, this is easily done. Go to www.aviationweather.gov and look for visual depictions. Insure you know how to navigate this website.
What are you doing about it?
Now that you have a rough idea of where you might encounter turbulence, what is your plan? First, reference your specific SOP/FOM and see if there is specific prohibition for flying in areas of known, or forecast, severe turbulence. This doesn’t mean cancel the flight. It means take an active role in avoiding these conditions. There are two ways in which this can be accomplished:
1) Vertically — See that your flight is planned above or below the area in question. If it isn’t, pick up the phone and call dispatch. Make the effort to avoid rough conditions by planning your flight to duck under or climb above the area in question. Whatever options you chose, remember to bring enough fuel. You can plan your route to be one cruise altitude or two different cruise altitudes.
2) Horizontally — You can also see about planning your flight around the area of turbulence (particularly severe) by filing a circuitous route. Without getting into the science of turbulence, there are specific sides to the jet stream that favor turbulence. The boxed areas of SIGMETS/AIRMETS/CWA’s have defined areas for a reason. The conditions for turbulence are believed to be greater inside and less outside the boxes. Changing altitude is not the only way to avoid turbulence. Lateral deviations could be the ace in your pocket.
Jet stream — the serpent in the sky
The jet stream plays a role in turbulence and there are ways to identify the jet stream and certain things to watch for by going to www.aviationweather.gov The two most prevalent indicators of high-altitude turbulence are pronounced troughs in the jet stream and jet streaks. I have already discussed troughs in previous issues. Jet streaks are pockets of accelerated air within the overall flow of the jet stream. Overall, the jet stream and jet streaks can both be identified at www.aviationweather.gov. This is a hugely beneficial and informative site.
As I always warn, I will deny giving any advice regarding flying. I will share what I do if I encounter a rough ride. Below are some things I might do, or keep in mind, when I encounter severe turbulence. Of course, your training, FARs, and your company’s and aircraft’s SOPs prevail.
1) Slow down to turbulence penetration speed.
2) Seat belt sign goes on with corresponding passenger announcements. Repeat your passenger PAs for good measure.
3) Seat your cabin crew.
4) Tighten up your belts. Are you wearing your harness? Do you know where your harness lock is located and how to use it?
5) Require that your passengers discontinue use of portable electronic devices. (This helps reduce the chance for flying laptops.)
6) Request block altitude.
7) Give consideration to disconnecting the autopilot and flying attitude and not altitude.
Are there others? Consider what other options you have for minimizing the pain of turbulence.
To date, I know of no on-board technology nor ground-based technology that depicts turbulence. We infer turbulence by the things we can see with our eyes, radar or varying wind speed and intensities. Clear-air turbulence is invisible by definition. Until something changes technology-wise, each of us will be pathfinders for identifying rough spots in the air. PIREPS get the ball rolling. Make them. Once things begin to unravel upstairs in the ride department, it’s up to us to take an active roll in avoiding what can be very dangerous conditions. Remember, we can start this process on the ground.