Ask The Captain: Turbulence, How Bad Is It Really?
Who actually likes turbulence? Thrill-seekers on a roller coaster, maybe. The rest of us, sitting in seat 14C, are generally not fans. So let's actually answer the question. How bad is turbulence, really?
What Is Turbulence
Most people blame turbulence on "air pockets." Let's retire that phrase and leave pockets to jeans and jackets. Instead, let's get into a little bit of physics, which somehow sounds friendlier than saying fluid dynamics. And to any physicists, engineers, or fans of Sheldon and Leonard reading this, apologies in advance for the oversimplification.
Is Air the Same as Water?
Obviously not, you're thinking. Walk through air to the beach and you stay dry. Walk through water on the way and you need a towel. Fair enough. But air and water actually have something in common: they're both fluids. Gases and liquids are both fluids, technically speaking. Okay, sure, but why does that explain my bumpy flight?
When a fluid moves, the ride can be smooth or rough. Picture a slow river gliding over a flat bottom. Nice and smooth. Now speed that river up and look at the shoreline. You'll start to see eddies, and yes, turbulence. That's what happens when a fast-moving fluid runs past something moving at a very different speed, in this case the shore, sitting still. The friction between them stirs things up.
Now speed the river up even more and toss a bunch of boulders on the riverbed. You get rapids. That's basically what happens when wind runs into mountains. The air behaves like a river hitting rocks, and it kicks up turbulence on the other side. So yes, in a very real sense, some turbulence is a whitewater rafting trip happening in the sky.
Real 'Air Pockets'
But don't those air pockets have to be real, right? The closest thing to an actual air pocket is turbulence created by the sun heating the ground on a bright day. When the sun warms the surface, the air just above it heats up and rises. Different surfaces heat at different rates. Walk barefoot across a white pool deck in Phoenix in July, then keep walking onto the blacktop parking lot next to it. That second walk is going to feel a lot different, because the air above the blacktop is rising much faster than the air above the pool deck.
Remember that river running past the shoreline? This is the same idea, just vertical instead of horizontal. Want to see it in action? Watch a thunderstorm cloud build. You can actually see it growing taller in real time. That's rising air, and it's moving fast.
The Jet Stream
Still skeptical about rivers of air moving through the sky? Turn on the Weather Channel and you'll meet the biggest one there is. The jet stream really is a river of air, a fast-moving current a few miles up that can steer weather patterns and generate plenty of turbulence of its own, mostly from the wind shear along its edges.
Does It Matter What Caused It?
Now that we know what turbulence actually is and where it comes from, does any of that matter? Turns out, yes. A big part of why turbulence feels unsettling is that it's an unknown. But knowing the cause doesn't automatically make it a non-issue. Let's get into what turbulence actually does, and to whom.
The Effects of Turbulence on the Airplane
Surely this can't be good for the airplane, right? If that's what you're thinking, you're probably wrong. Outside of extremely rare, extremely severe encounters, the aircraft itself barely notices. Wings are designed and tested to handle far worse than anything you'll feel in the cabin.
Take the Boeing 787. In flight, the wings flex as they generate lift. Boeing calculates the worst force the wing is ever expected to encounter, then the aircraft has to be tested to at least 150% of that worst-case number before it's certified. During that test, Boeing bent the 787's wingtips about 25 feet upward. That's not a computer simulation. That's an actual airplane, actually bent, on purpose, well past anything it will ever see in real turbulence.
Turbulence and the Pilots
If the airplane isn't bothered, surely it's a problem for the pilots up front. Also not really. Put a lid on your coffee cup and you're fine. Friends of mine who fly cargo don't even bother trying to avoid normal turbulence. The boxes in the back and the pilots up front couldn't care less.
Turbulence and Everyone Else
Someone has to feel it, and that's the flight attendants and the passengers. Flight attendants have to work harder to do their jobs when the airplane's moving around, and turbulence can slow service down or shut it off entirely. Nobody enjoys a full cup of hot coffee sliding around on a tray table, and trying to get work done on a laptop that's bouncing in your lap isn't exactly productive.
Turbulence also limits how much you can move around the cabin, and as it gets stronger, it restricts the flight attendants even more. And it's not just discomfort. Turbulence is genuinely responsible for real injuries, and the numbers back that up. Federal data on turbulence injuries shows flight attendants make up the overwhelming majority of people seriously hurt by turbulence, mostly because they're up, working, and unbelted when it hits, not because passengers strapped into their seats are getting hurt.
What's Being Done About It
There's no getting rid of turbulence. What we can do is avoid it and prepare for it. Over more than 30 years flying for airlines, I've watched forecasting tools get dramatically better, mostly thanks to advances in technology. That gives me the information to steer around known or forecast turbulence when I can, and sometimes dispatchers build the route around it before we even push back.
Even with much better forecasting, nobody can predict every bit of turbulence out there. Sometimes it's spread out enough that there's no route from departure to destination that avoids it completely. Having a solid picture of what's out there still lets me minimize how much we hit and prepare both the passengers and the flight attendants for what's coming.
What kind of passenger are you? Do you dread turbulence, tolerate it, or are you one of the lucky few who sleeps right through it? Let me know in the comments.
original publication 2019