How Pilots and Scientists Are Thinking About the Future of Air Travel

[Pilot] Attention, passengers.

Please return to your seats and fasten your seatbelt.

[Narrator] You know what that likely means, turbulence.

And if you've been getting on a plane recently,

it feels like turbulence has been getting a lot worse.

[passengers screaming]

So what does this mean for the future of travel?

In a few decades time looks a lot more turbulent

with hundreds of percent more severe clear air turbulence

in those skies.

[Narrator] And how are pilots reacting

to more and more rough air?

So we slow down just a little bit

to reach that maneuvering air speed,

so that it doesn't get bounced around as much.

[gentle music]

[Narrator] First, we need to understand

just exactly what turbulence is.

Turbulence is a chaotic random motion

that occurs in all fluids.

It's around us all the time.

It's in your bathtub, it's in your cup of coffee,

and of course it's in the atmosphere.

[Narrator] There are a bunch

of different types of turbulence,

but in particular we're going to talk about CAT.

[cat meowing]

No, not that kind of cat, but Clear Air Turbulence.

CAT is the particular type of turbulence

that is getting worse because of climate change.

And since it involves clear air in the jet streams,

it cannot be detected by radar before a plane is in it.

Clear air turbulence is generated

by wind shear in the jet stream.

Anyone who's ever climbed a tall building,

for example, the Eiffel Tower, very calm at the bottom,

but the higher up you go, the windier it gets,

and that increase in wind speed with heights

is what's called wind shear.

When the wind shear is too strong,

the atmosphere simply can't contain that

and it breaks down into turbulence as a result.

[Narrator] There are different levels of turbulence.

You have light, moderate, severe, and extreme.

Severe turbulence is turbulence

in which the up and downward motions of the aircraft

will experience vertical accelerations that exceed 1G.

Around 5,000 aircraft annually encounter severe turbulence

in the US causing hundreds of injuries

to passengers and flight attendants.

This severe injury causing turbulence is rare,

but of course, multiply that by all the planes

that are in the skies at any given moment

and one of them will encounter that severe turbulence.

[Narrator] For pilots,

turbulence is about maintaining passenger comfort

and trying to figure out where turbulence

could potentially be and then circumnavigating it.

So the forces on an aircraft

are lift, weight, thrust, and drag,

and air is a fluid, it's keeping it airborne suspended

at in flight at all times,

and turbulence is like a minor disturbance

in the middle of it.

[Narrator] How is climate change making turbulence worse?

What our satellites can see is the three dimensional shape

and structure of the jet stream,

and they've been measuring that for at least four decades.

There's an amplification of the warming

in the tropical parts of the planet,

and that effect is increasing the north to south

temperature difference across the jet stream,

and that's driving stronger wind shear in the jet stream

which is generating more clear air turbulence.

So that's the link from temperatures

to winds shear to turbulence.

[Narrator] This is what turbulence looked like in 1979,

and this is what turbulence looked like in recent years.

We see the same pattern except that the hotspots

are even hotter today.

There's greater likelihood

of encountering clear air turbulence in those hotspots.

50 or 60% more turbulence in some regions.

[Narrator] And this is what turbulence could look like

if global warming continues.

What we are looking at here is supercomputer simulations

of the atmosphere.

Now the simulation on the left is our control simulation,

whereas the simulation on the right

is one in which we've increased the carbon dioxide

to describe what a future real world might look like

with a lot more turbulence in the skies that we fly through.

What we find is that there's a doubling,

or perhaps even a tripling,

of the amount of severe clear air turbulence

in the atmosphere.

So the future in a few decades time

looks a lot more turbulent with hundreds of percent

more severe clear air turbulence in those skies.

[Narrator] And where will those hotspots particularly be?

There's 55% more severe turbulence over the North Atlantic

than there was in the 1970s.

41% more over the US and similar figures around the world.

That's the the definitive evidence really

that clear air turbulence

has already started to get stronger.

[Narrator] So what does this mean for air travel,

in particular over areas like North America

and the North Atlantic?

We're certainly projecting a doubling or a tripling

in the amount of turbulence in a few decades time,

but that will just mean that we go

from 0.1% of the atmosphere having severe turbulence in it

to 0.2 or 0.3%,

and that's certainly not going to mean we're gonna have

to shut down parts of air space

and say there's too much turbulence.

I don't think that's on the cards really.

It's just a case of turbulence becoming more frequent,

and pilots needing to keep even closer tabs

than they already do on where the turbulence is

and trying to avoid it as best as they can.

[Narrator] For pilots, this means relying on programs

like WSI Pilotbrief and SkyPath to plan out flight routes.

[Andrea] You're looking at a god's eye view

of our route of flight.

The various hazards along the way

are those big green circles and then the red boxes.

If you look at the bottom half of the screen,

that's a vertical profile.

You'll see that toward the end,

if it stayed at 33,000 feet it would encounter

that big yellow and orange section of turbulence.

And that's why in this case,

this aircraft has chosen to climb all the way up

to 39,000 feet to try to avoid it.

[Narrator] Pilots also use SkyPath,

which crowdsource turbulence data from other flights.

[Machine] Caution turbulence detected.

[Andrea] The yellow dots means they're encountering

light turbulence along the way.

And you can see that if you hover over any individual dot

like that orange dot there, it'll show you

you're gonna encounter moderate turbulence

at flight level 400 or 40,000 feet.

[Narrator] With this information in mind,

pilots can decide to circumnavigate turbulence,

for example, by adjusting altitude.

Clear air turbulence caused by jet streams

tends to be due to a very narrow band of air

that's moving very rapidly.

That narrow band of air

may only only be 2000, 3,000 feet thick,

and if that's the case, then you can just climb

or descend a couple thousand feet

and be out of it right away.

So when we encounter clear air turbulence

the very first thing we'll do,

of course, is turn the seatbelt sign on,

make sure we call back to the flight attendants,

and make sure they're either seated if it's bad enough,

or that they're checking the passengers are seated

if it's not bad enough.

We'll talk to air traffic control right away.

We'll figure out what the planes ahead of us are seeing

and if they're doing any better at any other altitude,

so we can climb or descend immediately.

[Narrator] And for pilots, this also means going as fast

as safely possible to get through turbulence.

Most of the time when we're flying

through clear air turbulence,

we're gonna keep the auto flight systems on.

Oftentimes, the auto throttles though in severe turbulence

are recommended to be turned off.

And the reason why is because those thrust levers

will be chasing around airspeeds pretty rapidly

and it's not necessarily good for the engines.

It's better just to leave them in one steady place

and hope that the airspeed is not chasing itself.

[Narrator] When pilots are in turbulence,

they tend to go out maneuvering air speed.

What that is, is the fastest speed that you can fly,

have full deflection of your control surfaces,

and not structurally damage the aircraft.

So we slow down just a little bit

to reach that maneuvering air speed

so that it doesn't get bounced around as much

and that we can go through at the quickest we can

without bouncing around the passengers too much.

The airlines are constantly changing

to adapt to our dynamic and changing air travel environment.

So if climate conditions make turbulence worse,

then we will continue to evolve

and make sure that turbulence procedures

are reflected in that, even if that means

different procedures to avoid it in the first place.

I specialize in turbulence.

I study it every day, I have done for 20 years.

But even for me, when I fly through turbulence

I feel that energy in my stomach, my heart racing.

It just plugs into a very primitive part of our brains

that logic can't override.

And I tell myself, I understand.

You know, this is why I study.

I'm perfectly safe.

It doesn't help.

A tip I heard recently is to order a drink

and just put the drink in front of you

and watch how still the water surface is in turbulence

because the emotions are a lot less severe than you think.