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Tableview
4th Jul 2012, 12:16
Article from the Sydney Morning Herald. It's the 'truth' as seen by the SMH but as people often post questions about turbulence here I thought it might be of interest to some. Some of the reader comments are interesting. It always amuses me that what a nervous flyer will describe as 'severe turbulence' is barely noticed by others. I was on a flight a couple of weeks ago ,we hit a few bumps, the woman sitting next to me was petrified, and I heard her on her 'phone when reached our destination telling someone : "It was the worst flight I've ever been on, I thought the wings were going to come off and we were going to crash ..."



Bumpy ride: the truth about turbulence

June 27, 2012


Comments 76 (http://www.smh.com.au/travel/traveller-tips/bumpy-ride-the-truth-about-turbulence-20120627-212au.html#comments)


Air turbulence: a pilot's view

"Will the wings fall off?" Qantas pilot Dale Newman explores the myths and reality of the terrifying air travel phenomenon.


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Turbulence can strike terror into even the most seasoned flyer. But do we actually have reason to be worried? Julietta Jameson investigates the things that go bump in the flight.
While plane disaster movies have fallen out of vogue since the September 11 terrorist attacks, you only have to search “flight turbulence” on YouTube (http://www.youtube.com/results?search-query=flight+turbulence&oq=flight+turbulence&aq=f&aqi=&aql=&gs-l=youtube.3...0.0.1.152.0.0.0.0.0.0.0.0..0.0...0.0.-OndGzxuyrU) to find out just how much of a bogeyman mid-air bumpiness is.
There's good reason why Hollywood has exploited it, newscasters have reported it and amateur video makers have captured it. Whether a person is the type of flyer who's snoozing the minute they board, or one who needs Valium to even step on an aerobridge, most will contemplate their mortality the minute the plane starts to jerk enough to make that free drink choppy.
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Turbulence can be caused by a number of factors, but in reality the plane doesn't move much at all. Photo: Getty Images

Says Captain John Holmes, who trains pilots for Virgin, Jetstar and Tiger through Ansett Aviation Training, “You're sitting back relaxing and suddenly you're jolted. It's psychological. And an plane is an unnatural environment. A lot of people are a bit nervous already.”
Turbulence damages more aircraft and injures more passengers and flight crew than any other aviation misadventure - besides crashes.
But it would take some pretty amazing turbulence to take down a commercial airliner. As a Boeing spokesman says, “Boeing planes are designed to withstand G forces that are one and a half times greater than the typical turbulence you would encounter.”
Serious injury figures are low. Between January 1998 and May 2008, there were 339 turbulence occurrences in Australia reported by airlines to the Australian Transport Safety Bureau. These resulted in over 150 minor and serious injuries to passengers and cabin crew. The most recent occurred in January this year, when seven passengers were injured on board a Qantas flight (http://www.smh.com.au/travel/travel-incidents/seven-injured-on-qantas-international-flight-20120108-1ppwp.html) from London to Singapore.
Stats from the US Federal Aviation Authority show that there have been three fatalities from injuries sustained during turbulence between 1980 and 2008 in the US, resulting in 298 serious injuries and three fatalities. Of the 298 serious injuries in that time, 184 involved flight attendants and 114 involved passengers.
At least two of the three fatalities involved passengers who ignored the seatbelt sign and did not fasten theirs. On that note, the FAA says, “Each year, approximately 58 people in the United States are injured by turbulence while not wearing their seat belts.” (They're not joking when they say 'buckle up', people.)
So just what is turbulence? It is irregular fluctuations in air, usually caused by weather.
“There are varying degrees of turbulence and most of the time we don't notice it,” says Professor Sylvester Abantoriba of RMIT's School of Aerospace.
There are also various types of turbulence including: thermal, which is vertical currents of air rising to meet cooler descending air: mechanical, which is caused by interference with the horizontal air flow by things such as mountains or buildings; convective, which is air currents moving up and down in clouds or thunder storms; and aerodynamic, or wake turbulence, caused by another aircraft. These are all visible and/or predictable.
Then there is shear.
This occurs when the direction or speed of wind changes radically within a short distance.
Often it changes from a slower speed to a jet stream – a band of high wind caused by the heating, cooling and rotation of the earth. The aircraft is jolted as it moves between the different wind speeds.
And it's this that is the most troublesome form of turbulence because it tends to be invisible.
“On of the biggest problems for long haul aircraft is the cruise altitude, 30-33,000 feet,” says Abantoriba. “That's where you have the jet streams that are not really visible to anybody, so you don't know about the turbulence till you are caught in it. It's called clear air turbulence (CAT). Sometimes it can be very strong.”
Often pilots will go looking for jet streams: on the route east across the Nullarbor, for instance, where one is known to exist and it cuts flight time and saves fuel. (It's avoided going when heading west.)
But the unpredicted jet streams are the troublemakers.
The new Boeing 787 Dreamliner is a equipped with a 'turbulence dampening system'. It has sensors that read the air in front of the plane and attempt to predict the effect the air will have on the aircraft. Computers then send signals to the control surfaces to lessen the impact of the turbulent air.
And Abantoriba says “researchers are working on further models which they hope will be installed in aircraft and will use the environmental data to predict such occurrences.”
But a lot still depends on pilots who, in the event of turbulence, will slow the plane.
“The pilot slows down to set figures we call turbulence penetration speed, which is the optimum speed for that particular plane when it enters turbulence to smooth the ride. You can hear the engines being retarded when they slow down,” says Holmes.
Regardless of the noise, which may alarm some, “Handling it is taught, studied and practiced by pilots. The danger is minimal.”
The Pacific is prone to serious levels of turbulence as are the Equator and Central Africa, California and Alaska.
“And generally if you're flying up to Singapore or Hong Kong, you'll often find when you get to the subtropics area that the seatbelt sign will come on because they know you're getting near the jet stream area,” says Holmes.
Once an aircraft finds turbulence, the pilot will report it so others can avoid it.
But how bad is bad? The experts (and the statistics) say most flyers will never experience severe and prolonged turbulence.
“We're only talking about a very small amount of flight time,” says Holmes. “And most flights you won't encounter much at all. In actual fact the plane doesn't really move much at all. It appears to. You might be only talking centimetres of movement. The plane can feel like it's moving a lot but your drink will stay in your glass. If you were dropping a lot, that liquid would actually come out of your glass.
“Most aircraft will be travelling over the ground probably about one and a half football fields a second. If in that first length there's an updraft, it's more than possible that there is a downdraft on the next length. So it's evening itself out ever so quickly. The aircraft is not actually moving much.”



Read more: Bumpy ride: the truth about turbulence (http://www.smh.com.au/travel/traveller-tips/bumpy-ride-the-truth-about-turbulence-20120627-212au.html#ixzz1zegEU77n)

LondonPax
4th Jul 2012, 12:59
Thanks for this - it's interesting. I'm not a nervous flyer, but turbulence does worry me. I don't mind light turbulence but when it gets heavy I get nervous. Not conducive to a good night's rest. I understand that "light" and "heavy" are subjective. I recently flew back from Hong Kong (777) and there was some pretty heavy (to me) turbulence, to the extent that cabin crew were told to sit down and strap in. I haven't heard that order being given much ... does that mean it's pretty bad?

I've found that turbulence on the BA LCY - JFK route to be quite troubling, as the A318 is a relatively small aircraft, compared to what you'd fly on that route from say LHR, so moves about a lot.

radeng
4th Jul 2012, 14:10
The worst I've had was a very long time ago - you can tell, it was on PanAm flying into Berlin. Not only were we in a thunderstorm - bright flashes and a noise like a bucketful of small stones thrown against the hull, which I assume were lightning strikes - but the CC were strapped in and one of them was trying to use the barf bag without anyone noticing....

I found it interesting rather than frightening, but the aircraft was jumping around more than a little bit.

The other time was wake turbulence on a Bristol to Paris flight as we got to the French coast. The four of us drinking champagne didn't spill a drop, but three people drinking coffee had a small bath in it......There's a moral in that somewhere!

Back in the mid 1980's, there was an article in Flight that said some 60 people a year were injured by turbulence on the North Atlantic route because they weren't strapped in. Since reading that, I only unbelt to go to the lavatory...

MarkerInbound
4th Jul 2012, 14:19
Lightning doesn't make any noise striking the plane but you hear the thunder. Rain and hail sound just they do in your car, if it was going 400 miles an hour.

DaveReidUK
4th Jul 2012, 16:14
As a Boeing spokesman says, "Boeing planes are designed to withstand G forces that are one and a half times greater than the typical turbulence you would encounter."

I doubt very much that any Boeing employee ever made such a ridiculous statement.

One-and-a-half times greater than typical turbulence ?

wiggy
4th Jul 2012, 17:03
cabin crew were told to sit down and strap in. I haven't heard that order being given much ... does that mean it's pretty bad?



Often if we get plenty of warning that turbulence may be significant enough to pose a risk to unrestrained cabin crew we'll tell them to be seated via an "interphone" (telephone) call. The passengers will probably already be strapped in and blissfully unaware of the extra precautions. We generally only make a announcement over the public address if we need them seated quickly, and that generally happens if we get little warning of the turbulence, it doesn't neccessarily mean the bumps are going to be especially bad.

Hartington
4th Jul 2012, 18:36
One of the problems/fun things about Pan Am into Berlin was that even when the jets arrived the flight were not allowed above 10,000ft (I think) because the corridors were set at the end of the war when 10,000 was high.

radeng
5th Jul 2012, 12:01
You can tell it was a long long time ago that I last went to Berlin! But going again in September for a meeting. I had a feeling it was lower than 10,000 feet, but I can't remember.

LondonPax
5th Jul 2012, 12:17
Wiggy - that's good to know - thanks.

jetset lady
5th Jul 2012, 13:54
I've found that turbulence on the BA LCY - JFK route to be quite troubling, as the A318 is a relatively small aircraft, compared to what you'd fly on that route from say LHR, so moves about a lot.

I have a bit of theory about this. I work on both the 777, usually down the back, and the A318 and have always found the A318 to be a little more stable. I've always assumed it's because it has less length to wobble around, if that makes sense! However, I have heard other passengers on the A318 say the same as you, LondonPax. I wonder if it's more a case of where you are sitting than the aircraft type.

It's known that turbulence is felt more towards the rear of an aircraft, to the extent that the crew at the front can be happily skipping around the cabin while we at the back are hanging on to seat backs. Most of our passengers on the A318 will be used to travelling towards the front of a wide body, in Club or First. The 318 is the only time they may travel at the other end. Could it be this, plus the perception that it's a small aircraft and therefore, people expect it to be more affected by turbulence?

Obviously, if you usually travel in 1A on the 318, that shoots my theory down in flames! :O

LondonPax
5th Jul 2012, 15:32
jetset lady - in fact, whenever I've done the LCY- JFK route on the 318 I've been sitting near the front. Not necessarily 1A but close to it. But maybe it was even worse down the back.

Mr Mac
5th Jul 2012, 21:36
Have had many intresting flights with turbulance, but the most extreme were some time ago eg carts /crew airborne 1960/70,s warning /radar improvments appear to have improved, or maybe I am just lucky. Fly quite often over ITCZ and have yet to suffer anything like some of my flights over same areas in 707,s in that period. Flying early Friday in UK into Europe and looking at storm forcast could be sporty trip, so may be back onto reserve judjment, but in my experiance Europe can not compete with ITCZ turbulance.

PAXboy
5th Jul 2012, 21:55
In the numerous trips to/from South Africa, crossing the equatorial zone at night - the turbulence is definetly less than it was even 20 years ago.

If you follow the flight on the skymap and watch the 'snail trail', you can often see where you have made a diversion and then back on track. Worst turbulence was a Viscount in a sub-tropical thunderstorm at FLO160 in 1971. Not good!

Then there was a DAK from JNB to WDH (Windhoek) just about everybody on that school trip was ill during the interminable flight.

An American boss of min ein the 1980s said that, when he was in the USSAF as an electrical engineer - they were testing new radar and to see how equipment under test would work in severe turbulence. So they WENT LOOKING FOR IT!!!!!!

He got the job of onboard test engineer as he was impervious to motion sickness and was perfectly happy studying the equipment - whilst being bucketed about! He was a nice guy and showed no other signs of madness.

OFSO
6th Jul 2012, 09:17
There's no such thing as turbulance. It's the guys up front pulling the side stick back and forth and side to side when they get bored and want to throw a scare into nervous passengers.

ExXB
6th Jul 2012, 10:16
There's no such thing as turbulance. It's the guys up front pulling the side stick back and forth and side to side when they get bored and want to throw a scare into nervous passengers.

Actually it's an IATA resolution requiring the implementation of CIFT (Cockpit initiated flight turbulence) particularly during meal service.

This puts all airlines, or at least IATA members, on an equal footing.