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Pilots Explain Why We Shouldn't Worry About Turbulence

"We avoid turbulence because it's stressful for passengers," says former military pilot Keith Tonkin, "but for pilots it's just not an issue."

by Julian Morgans
Jul 27 2015, 3:30pm

Illustration by Carla Uriarte

Ever since MH370 vanished and AirAsia crashed into the sea and Andreas Lubitz scattered Germanwings flight 9525 over the French Alps, I've felt in my bones that—science and logic aside—planes don't work. They simply run on luck. And of all the problems with flying, turbulence is the worst. There's a special type of helplessness induced by a rattling plane, and especially when you don't know why it's rattling. So in order for me to relax on flights, I asked some pilots to explain turbulence.

"Turbulence isn't something to be feared," says Keith Tonkin, who is a former military pilot and director of consultancy group Aviation Projects. "Modern planes are designed to withstand far more force than turbulence can create. They're simply not going to fall apart." He adds that military planes routinely fly into cyclones to take meteorological readings, just to underline how robust they are.

Construction aside, I want to know if turbulence can jolt a plane out of the sky. I remind Tonkin that in November 2001, American Airlines Flight 587 crashed after takeoff from JFK Airport in New York, killing all 260 people on board, along with five on the ground. And the reason? It took off behind another plane, and was brought down by the turbulence in the plane's wake.

But as Tonkin assures me, the problem was that Flight 587 took off too soon. As he points out, human error is the most common reason planes go down, whereas meteorological turbulence is more of a hassle than a danger. "We avoid turbulence because it's stressful for passengers," he says, "but for pilots it's just not an issue."

Turbulence comes in three main categories: thermal, mechanical, and shear. Essentially, all three are small-scale versions of actions you'll have seen in flowing water. Warm air rises, in much the same way as water billows up from the deep. This is called thermal turbulence, and you experience it as a bump as you ram a jet through a rising plume at 500 mph. If you've ever flown through afternoon clouds at takeoff, you'll have probably experienced thermal turbulence.

Then there's mechanical turbulence, which occurs when physical structures such as mountains and buildings disrupt wind currents, much like a boulder causes ripples in a moving stream. This is dangerous, but very easy to predict and pilots simply avoid flying near big structures at low altitudes.

A compilation of planes hitting shear turbulence while landing

The last type is shear turbulence, which basically describes the border between two pockets of conversely moving air. This is the scary one because you often can't predict how bad it'll be, such as the case when the pilot flies a plane in and out of a jet stream.

A jet stream, like a freeway of air, is a band of wind gushing through the upper atmosphere. To minimize fuel consumption, pilots often jump into these streams to get a tail wind. You might have been half asleep to hear the seatbelt light ding on, informing you the pilot is about to move in or out of a jet stream. Usually at this point the pilot will know what to expect, as another plane will have logged the severity of the turbulence over the transitional zone.

Turbulence is recorded and shared across planes according to a rating system. Light turbulence describes a movement of a foot or two, and rattles the drink tray. Moderate turbulence is the point at which air hostesses strap themselves in. Severe turbulence will launch unsecured objects, including people, although most pilots only encounter severe turbulence a few times in a whole career. But extreme turbulence is really the sum of all fears. It this case, a plane can drop or ascend 100 feet in a few seconds, and unbuckled passengers have been killed rattling around the walls. As the US Federal Aviation Administration reports, "From 1980 through 2008, US air carriers had 234 turbulence accidents, resulting in 298 serious injuries and three fatalities."

2013 was the safest year on record, while 2014 wasn't all that far behind.

Ron Bartsch is the chairman of AvLaw Consulting, and the former head of safety at Qantas. He says that extreme turbulence is extremely rare although he was unlucky enough to once hit a patch. "I remember flying a little twin seater, back into Sydney over the Blue Mountains." He said. "There were storms and some mechanical turbulence over the mountains and I was flying fairly low, only around 10,000 feet." He describes hitting a sudden wall of air that ripped him skywards, to where there was a lot less oxygen. "The plane was unpressurised and I was terrified I'd black out. I had the nose down the whole time but jumped from 10,000 feet to 12,000 feet. It's moments like that you really earn your wage as a pilot."

This is an example of why commercial pilots will go to some lengths to avoid turbulence. A commercial airline would never approach mountains at 10,000 feet and will always fly around thunderstorms rather than go through them. And again, it's not because planes can't withstand these conditions, but because the average passenger won't understand what's happening. To both Keith and Ron, hitting turbulence seems to be a bit like hitting a pothole. It draws unwanted attention to the driver, but it doesn't cause problems.

"It seemed like a lot of planes went down last year," says Ron Bartsch, addressing my essential problem with planes. "But that's more perception than reality. 2013 was the safest year on record, while 2014 wasn't all that far behind." He also points out that last year's high-profile crashes were unprecedented, and none were the result of air turbulence. And then he tells me to look at some numbers.

Three billion people flew in 2014, with 692 commercial fatalities. With numbers like that, you've got a better chance of winning the lottery than dying in a crash.

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