Rough rides caused by potholes in the sky

Despite recent news about flights troubled by turbulence, air travel is still one of the safest ways to go. Photo / Daily Post

Last week 22 people were injured in two separate flights due to air turbulence. So what exactly is turbulence, how can it be avoided, and how dangerous is it?

Over the past few years there have been a number of reports of severe air turbulence affect flights overseas - but with all our weather technology why is it some planes fly straight into it? And what's it like being a flight attendant and dealing with this every single working day.?

To start with, it's important to point out the two main types of air turbulence - there's the turbulence involved in cumulus clouds, like shower clouds or thunderstorms, then there's clear air turbulence (known as CAT). CAT is the one that is most dangerous, simply because it's invisible.

While the turbulence in a thunderstorm is probably far more severe it's next to impossible to fly into a thunderstorm these days. Either because you can clearly see it in front of you, or, through the various weather instruments onboard, the latest rain radars, or from air traffic control, you just fly around it.

Inside thunderstorms there is something called wind shear. Wind shear has been related to numerous major fatal air crashes around the world but these days it's rare. This is basically a severe wall of wind that can slam a large commercial airliner straight into the ground.

So planes fly around thunderstorms, or, as they fly into smaller clouds, prepare themselves for the upcoming turbulence.

CAT is far more risky. It happens on blue sky days or clear nights. Without warning a plane may drop over a hundred metres (4 or 500 feet) in a heart beat. Worst of all, most weather instruments onboard can't accurately detect them.

Pilots do have a rough idea where this turbulence can lie. In North America there is a major jet stream that swirls over the USA and Canada in a large sideways S shape. This is a narrow band of fast moving air associated with turbulence. Most pilots flying across Canada and America fly thought this jet stream every day. They usually know roughly where it is and sometimes they will climb or descend to avoid it.

Other flights in the area can also radio pilots to warn of upcoming turbulence in the air.

In New Zealand a lot of our turbulence would be formed by mountains and clouds. Our jet streams usually lie to the north and to the south of the country - placing us in our 'temperate' zone.

A friend of mine at work has a huge fear of turbulence. I told him it's just pot holes in the sky - nothing to worry about - and planes almost never crash due to turbulence - which is true - however there are some instances where CAT has caused injuries - even death.

A Continental flight crossing the Caribbean last year hit major turbulence, which ripped ceiling panels out and seriously injured a number of passengers. And just this past week a United Airlines flight over America hit turbulence which injured 21 passengers, one seriously. Just 24 hours later another American plane was hit by turbulence and a flight attendant was slammed against the EXIT sign on the roof, he was taken to hospital after the plane safely landed...he obviously knew where the exit was.

With so many flights over America, the large jet stream, the Rocky Mountains and humid air from the Gulf of Mexico it's not surprising that America has more than its fair share of turbulence injuries.

In 1997 a passenger died after receiving serious injuries onboard a United Airlines 747 from Japan to Hawaii - that is incredibly rare. In fact, AirSafe.com has only found six passenger deaths in flying history.

So what's it like working in these conditions? The pilot is most likely sitting down or strapped in safely, but what about the flight attendants who are walking about?

I've made a few international flights in my lifetime and there's one sure place where you hit turbulence - over the tropics. This is due to the heat at ground/sea level rising. Even at 30,000 feet you can still fly through clouds. In one particular flight I remember actually being scared, my knuckles white, as the 747's engines slowed down at first, to ride out the bumps, then the engines screamed up as we climbed over the clouds.

But I felt sorry for the attendants... some passengers were pressing their service buttons wanting glasses of water or food etc. Maybe they were scared? I don't really know. But I know that I didn't want to bug attendants at that one time and make them risk their lives to walk down the aisle. I sat and watched as a flight attendant very slowly walked down the aisle...seat...by seat...by seat...to finally reach this passenger near me - who just wanted a glass of water. I could see it in the attendant's face - "I walked all the way down to you for that?". I'm assuming for the rest of that flight they "accidentally" woke him up by banging his arm every time they walked past.

Another friend of mine is a flight attendant - and he says he can honestly say he doesn't get scared in turbulence but says when CAT occurs it does give you a bit of a fright.

He says the flight deck are fantastic and usually give the attendants plenty of notice about upcoming turbulence.

As a crew member you do get used to it, standing up in the cabin with the little niggles is just second nature, and he likens it to getting your sea legs on a boat.

He says the worst turbulence he experienced was CAT on his second trip on a 747 three hours into a flight to LAX (Los Angeles).

"We were in the cabin collecting in the meal trays. We could actually feel this one coming, it was like driving over a dip on the road when you get that funny feeling in your stomach, we dropped 400 feet! I had to grab the seat arm and the cart to stop myself and the cart from getting airborne. Trays, casserole dishes, glasses all crashed down in the cart, the galley was a mess too.

"No injuries on that flight or any of my flights but I know of crew that have hit the roof in the galleys, the worst one that I can tell you about was a crew on a 737, severe turbulence around a thunder storm in Sydney. Two of the four crew were hospitalised (broken bones) and one was that scared she never flew again".

These are the worst case scenarios, however. If you're afraid of flying because of turbulence this blog should show you that while there are, very rarely, injuries from turbulence, there are far more dangers simply in driving to and from the airport in your own car.

We all encounter turbulence on flights, and usually it's minor.

And maybe I'm a little odd - because I find turbulence quite calming. Just like a rocking car puts a baby to sleep I'm the same on a plane. If you can't sleep, here's another tip to bring a smile to your face - try watching the back of everyone's heads in front of you as they all bounce in time and to the same direction. It makes me laugh every single time. Oh and listen out for the one middle aged woman who goes "Ohhhh" every time you hit an air pocket.

I am a complete plane geek - I love watching them fly over my house, I love being in them even more. If I was any good at maths, and didn't have Meniere's Disease (a tiny inner ear disorder that, from time to time, gives me some balance problems) I would've become a pilot.

Flying is still the safest way to travel... despite writing this blog I'm already looking forward to my next flight.