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| What tools do airline pilots use to predict upcoming bumpy air? |
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Airline Pilots And Turbulence
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Pilots have onboard equipment to track weather, but they
also rely on reports from air traffic control and other pilots in the region. |
How Do Airline Pilots Know Turbulence Is
Coming Up?
BY PATRICK J. KIGER
Hopefully,
you'll never be on a plane that's caught in an unexpected stretch of severe
turbulence, such as a recent ill-fated Aeroflot flight from Moscow to Bangkok,
in which at least 27 passengers reportedly suffered injuries that included
broken bones.
Most
turbulence incidents aren't anywhere near that severe or dangerous.
The
Federal Aviation Administration recently reported 44 injuries due to
turbulence in 2016.
That's
not a lot, when you consider that 932 million passengers flew on domestic
airline flights that year.
According
to a USA Today analysis of the data, aside from a passenger who
suffered a fractured vertebra on one flight, most serious injuries were
sustained by flight attendants who were thrown around while they were standing.
One
reason why there are relatively few turbulence injuries, undoubtedly, is that
airline pilots are pretty good at figuring out in advance that turbulence is
coming up, and then warning passengers ahead of time.
If
you've ever been on an airline flight, you've most likely heard the
public-address system give off that little ding, followed by a flight attendant
informing you that the captain is asking passengers to get back in their seats
and put on their safety belts.
So
how do pilots predict that the air is about to get bumpy?
They
have multiple sources of information that they can rely on in predicting
turbulence, and in many cases, they're able to minimize its effects or even
avoid a turbulent area of the sky completely, according to Ron Carr.
He's
a veteran U.S. Air Force pilot who went on to fly for American Airlines for 16
years, and now is an associate professor in the department of aeronautical
science at Embry-Riddle Aeronautical University.
Carr
explains that there actually are three types of bumpy air that airliners
encounter.
The
first is convective turbulence, the sort that occurs when a
thunderstorm generates powerful up and down drafts of air.
There's
also mountain wave turbulence, which is caused when air flows over
the tops of mountains and creates waves, the way that waves in the ocean will
break due to an underwater reef.
Finally,
there's something called clear air turbulence, which is created
when a mass of warm air collides with a cold-air mass.
Carr
says that measures to avoid a rough ride actually start on the ground before
takeoff, where dispatchers and meteorologists work together to come up with the
smoothest, safest route for a flight based on what they know is going on in the
atmosphere at the time, and what's predicted to happen.
Once a plane is in the air, the flight crew has a
weather radar display in the cockpit to provide the latest info on conditions
ahead. "Thunderstorms are going to
generate turbulence - no doubt about that," Carr says. "They can pretty well predict
those."
The
image on the screen is displayed in three colors that show the amount of
precipitation, a good indicator of convective turbulence.
Green
indicates light to moderate turbulence, yellow shows an area where it's likely
to be rougher, and red signifies areas that should be avoided.
Normally,
pilots will deal with thunderstorms by simply altering their route to avoid
them, but sometimes, when multiple storms are lined up in a row and a course
deviation would require too much fuel, a pilot may pick the weakest storm area
to fly through.
In
those instances, the passengers are going to be advised to return to their
seats and buckle up.
It's
possible to anticipate mountain wave turbulence as well.
There
are charts and maps that predict it, and when flying near a mountain range such
as the Rockies, a pilot also can look out the window and study the cloud
formations — the presence of lens-shaped lenticular clouds at the plane's
altitude, for example, is a tipoff that a bouncy ride could be ahead.
Clear
air turbulence — the sort that apparently banged the Aeroflot plane around — is
more difficult to predict.
Weather charts can show where air masses of different
temperatures might collide, but as Carr says, "it's not an exact science."
That's
why flight crews also rely on warnings from other pilots who've recently flown
in an area.
In
some cases, they actually may hear warning over the radio from a plane that's
ahead of them.
More
often, they rely upon pilot reports — PIREPS, in aviation lingo — that are made
to air traffic control, which then relays the information to whomever is flying
into an area with turbulence.
According
to Carr, pilots may get turbulence warnings anywhere from five to 10 minutes in
advance if they're listening to a plane ahead of them, and up to 20 minutes in
advance if the notifications are coming from air traffic controllers.
That
often gives pilots a chance to request permission to make a maneuver to avoid
the worst of the turbulence, such as deviating from course to the left or
right, or ascending or descending in altitude.
Afterward,
they can request permission to return to their original track.
But
even with those maneuvers, a plane may still encounter some bumpiness.
And that's why passengers hear that instruction to
buckle up. "If we're expecting any
turbulence at all, or even the slightest chance, we're going to get the flight
attendants seated and the passengers belted," Carr says.
And
it's important to follow those instructions.
Turbulence
isn't necessarily a danger to the aircraft, since modern planes are
designed for resilience, and pilots can slow down to reduce the effect of the
forces to which they're subjected.
But
it can be a danger to passengers who aren't strapped in, Carr says.
"Most
injuries in turbulent conditions are because people are caught without
seatbelts," he says.
"Just
leave it on. It would save a lot of injuries if people did that. If you're not
strapped in, you're going to take some real quick flying lessons. And then when
gravity takes over, that's going to hurt."
NOW, THAT'S INTERESTING
According to a 2016 study by
Paul D. Williams, an associate professor in the meteorology department at the
University of Reading, clear air turbulence could increase significantly in the
future because of climate change.
Patrick J. Kiger
has written for HowStuffWorks since 2008 covering a wide array of topics, from
history and politics to pop culture and technology. He worked as a newspaper
reporter for the Pittsburgh Press, and the Orange County Register in
California, where he covered one of the biggest serial murder cases in U.S.
history, and also as a staff writer at Baltimore Magazine. As a freelancer,
Patrick has written for print publications such as GQ, Mother Jones and the Los
Angeles Times, and on the web for National Geographic Channel, Discovery News,
Science Channel and Fast Company, among others. In recent years, he's become
increasingly interested in how technological advances are altering urban life
and the design of cities, and has written extensively on that subject for Urban
Land magazine. In his spare time, Patrick is a longtime martial arts student
and a fan of crime fiction, punk rock and classic Hollywood films.
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| The most reliable strategy for safety during turbulence may be the simplest: buckle up! |
