I was once on a flight over Africa where there was a lengthy delay before take-off owing to thunderstorms over the airport.  We encountered a further huge storm en route to our destination, and despite diverting around it, we experienced severe turbulence.

Boisterous drunks on board quietened up before becoming quite ill, and in addition to the seat-belt lights being kept on the whole way, the cabin crew were ordered to their seats by the captain.

Initially it was quite fun, but the fun stopped after a short while.  It was definitely a white-knuckle roller-coaster ride.

Turbulence gives one the impression that the aircraft is flying out of control, but it is not.  The aircraft may feel as if it is going to come apart.  Again, it will not do that.

Pilots try to avoid turbulence, largely for the sake of the passengers.  Cargo planes regularly fly through turbulence that passenger planes avoid, and they do not fall out of the air.

As uncomfortable as it was, the plane was never in any danger.  Not even if it had been struck by lightning, which commercial aircraft are designed to be able to cope with.  Your plane will almost always be under control of the autopilot when going through turbulence.  The autopilot has a special setting for turbulence in which it makes fewer, and more gentle corrections.  This relies on the tendency for aircraft to self-correct from most random flight changes resulting from air movements.

As with anything else, turbulence varies in extent and intensity.  There is a four-point scale for it:

• Light.  You can feel it, but you can walk around okay and the seatbelt lights remain off.

• Moderate.  It is still possible to walk and the cabin crew continue their duties but the seatbelt lights are put on.

• Severe.  What I experienced in my tropical flight above.  It is unusual.  Cabin crew are commanded to their seats.

• Extreme.  This is very rare because of all of the precautions taken to avoid it.

So, what are the real dangers associated with turbulence?

1. Loss of altitude when you are close to the ground.  If you are close to the ground and you get pushed down, the plane could hit the ground.  Thunderstorms can cause this and aircraft will not take off when a storm cloud is over the airport.  The pilot may divert the flight to a different airport to ensure safety, or the plane may be put into a holding pattern in a safe part of the sky until the weather in the region of the landing field has improved.

2. Gusts near the ground.  One pilot I spoke to told of a landing at Schipol when the plane was hit by a gust of wind just as he lined up the plane with the runway in a side-wind.  The jet’s wings rotated several degrees in a second and it was all he could do to level the wings and slam it on the ground.  Fortunately it was a cargo flight, so there were no complaints.  Passenger flights are typically diverted to another city if there are strong side-winds at the destination.

Aircraft and airports are both equipped to detect wind shear conditions that could otherwise be of danger to the plane.

3. Injury.  Passengers who are not belted in can be thrown against the roof of the cabin.  Persons have in fact died or have been seriously injured, particularly when flying in “clear air” with the seatbelt lights off when unexpected turbulence has been encountered.  Loose objects such as the drinks trolley can be flung against you, causing injury; and luggage can shift in the overhead lockers and spring the lock, dropping items on you.  The best you can do to protect yourself against this is to keep your seatbelt on for the whole flight.

4. Structural failure.  Over the years a disturbing number of light planes, not equipped with weather radar and with only basic instruments (flying according to Visual Flight Rules) have come to a bad end through falling apart in bad weather.  Commercial operators are better equipped and will reroute or reschedule if the weather outlook is poor.  The planes are also, as the cost would suggest, stronger and more reliable than private aircraft.  And the pilots are much less inclined to take unnecessary risks.

All things said, turbulence can be extremely uncomfortable but it is very rarely a source of real danger.

Photographed by Adrian Pingstone in August 2002 and released to the public domain

Before take-off

Once you’ve been welcomed aboard the flight by one of the cabin crew and located your seat, you can stow your luggage either in the overhead compartment or under the seat in front of you.  (The disadvantage of putting it under the seat is that it can reduce your available leg-room.)

Once all the passengers are boarded and seated, the cabin crew will start the safety briefing. They will show you how to do up and unbuckle your seatbelt, indicate where the exits are and show you how to inflate and deflate your lifejacket.  They will also show you how to operate the oxygen masks that will drop down from the ceiling if there is a sudden decompression.  (Decompression is very rare and few travellers have ever actually experienced it.)  They will do a final check down the aisles to make sure everyone has their safety belts on.  (The correct way is snug, and low down, across the hips.)

After being pushed back by a “tug” the aircraft will taxi to the runway under its own power.  It is customary for the captain to introduce himself and his team.  He will then make the announcement, “cabin crew, prepare cabin for departure”.  At this point you are just about set for take-off.

The cabin crew will “arm” the doors and check on each other to make sure that this has been done, before seating themselves.  The doors cannot be opened when the aeroplane is under way.  The “arming” is to ready the mechanisms that will operate the slides that will automatically deploy upon opening the doors when the airplane is on the surface.  (If the take-off is aborted, for instance, the doors will be opened, the slides will deploy, and everyone will be evacuated from the aircraft.)

Take-off

The pilot will line up the plane neatly on the runway.  The engines tone will rise as they push out maximum thrust.  The aircraft will leap forward eagerly and then gather speed quickly in order to get lift for take-off.  The acceleration will push you gently into your seat.  At a given speed (on a signal from the co-pilot) the pilot lifts the nose gently off the ground and the acceleration continues with the plane balanced on the main wheels, kept in place by the lift on the wings.  (You will usually not notice this).  For technically-minded readers, this phase of the takeoff is called “rotation”.)  Once the craft reaches take-off speed the pilot will pull back on the controls and lift the front of the plane into the air.  You may sometimes hear a faint thump as the wheels leave the ground.

From there the plane will climb sharply, gaining speed and altitude as it goes.  The rate of climb will gradually decrease and the plane will adjust to a move horizontal angle as it approaches cruising altitude.

Why the sharp angle after takeoff?  Once take-off has been achieved then the plane will fly an optimal route to get up to cruising altitude as soon as practically possible.  Quickly achieving altitude gives room for manoeuvre in case of any problems, and also gets the plane out of the immediate vicinity of the airport, reducing the crowding of the controlled airspace.  The aircraft becomes more efficient to run as it gets to the designed cruising speed and altitude.

Take-off noises

Shortly after takeoff the wheels and landing gear will be retracted into the aircraft fuselage, which can cause a slight thump, and the wheel-bay doors shut.  Once in the air, you will hear an assortment of sometimes quite loud noises.  These are normal.  The pilot’s actions are supported by hydraulic power, which ensures that he can control the rudder and other flight control surfaces, which would otherwise require inhuman strength.

Slats and flaps

It can be very disconcerting for first time flyers sitting at the window to see gaps appear in the wings before and during take-off, as shown in the picture accompanying this article.  The structures at the front of the wings are called slats.  The hinged ones at the back of the wing are called flaps.  A number of modern jets fly at a cruising speed of over 800 km/h (500 mph).  Without slats and flaps the takeoff speed would need to be a significant proportion of that speed!  By using slats and flaps the lift of the wing is significantly increased, essentially by increasing the curvature of the wing, which sharply reduces the speed necessary for flight.

After takeoff, once the speed has increased, sufficient lift is generated by the wings without the slats and flaps, due to the increased airspeed.  The devices are then progressively “packed away”.  This is also done using hydraulic power and the changing of the wing to its sleek cruising shape, without holes in it, will usually be accompanied by (sometimes loud) noises from the hydraulic system of the aircraft.

Now that you’re in the air, you should enjoy your flight.  This is one of the safest modes of public transport in the world today.

Brace for Impact

Some airlines only provide detailed information on the brace position to business class passengers and up, even for a fee.  (In mid-2011 British Airways were charging £135 for a course giving you full and proper instruction on emergency procedures.)  Here on DIY Travel Expert you can read it for free!

To be frank, the safety charts are often of scant use at all in helping you to understand the brace position.  Airlines are stingy about space and cram as many passengers into the cabin as possible.  As a result. few passengers have the luxury of the amount of space depicted in the diagrams, where the seat in front of you is not a factor.  Most times you are going to have to brace yourself right against the back of the seat in front of you.

Emergency

In an emergency the captain will usually make a brief announcement warning passengers to brace for impact.  Under certain circumstances the cabin crew will make the announcement, for instance if they recognise that something unusual and bad is happening during a takeoff.

You may only have a few seconds to respond.  The captain may say as little as “Brace for impact” or “Prepare for crash landing”.  At that stage he has troubles of his own and you should not expect lengthy instructions.

Cabin crew have their own positions which are different from yours, because their seats are different.

Preparation

1. Before you leave home: One seldom thinks of clothing as a factor in crash survival but it is worth a brief word.  Experts consider the best dress for a flight to be long pants, a shirt with long sleeves and closed lace-up shoes.  High heels are going to have to stay on the plane if you crash and you will lose time in removing them.  Sandals may not protect you from sharp debris or glass.  Nylon clothing is to be avoided because it burns readily and has poor thermal properties. Wool is best for thermal insulation when wet, and cotton has excellent wicking properties if you come down in a jungle, for instance.  If you are flying over snow and ice in bad weather, consider carrying a warm jacket on your lap.

2. It has been suggested that you should buckle and unbuckle your belt a few times when you first sit down, to create “muscle-memory” of where to find the buckle.  It is in front of you, not to the side as it is in cars.  You do not want to have to think about where your buckle is in the possibly confusing aftermath of a crash.

3. After the safety briefing, count and memorise the number of rows to the nearest exit.  It could be dark or smoky when you need to find your way out.

4. Before a crash ensure that your seat belt is securely fastened.  This means having it with no slack, and pushing it down as far as it will go, to avoid internal injuries.  (You want the belt to stop your movement using your pelvis, which is strong, and not your gut.)

5. Put your seat fully upright before getting into the brace position.

British brace position

Lean forward and rest your head on the seat in front of you as far below the tops of the seats as possible.  Place your hands on your head, but not interlocked.  One hand resting on top of the other.  Your feet should be tucked underneath your knees, flat on the floor.  Pull your elbows in towards your body.

The UK guidelines are more recent than the US ones, having been mandated in 1993 following analysis of injuries in the 1989 Kegworth disaster (British Midland Flight 92).

American brace position

Lean forward and rest your head on the seat in front of you as far below the tops of the seats as possible.  Place your hands on the seat in front as well, with one hand holding the other wrist.  Position your forearms at the sides of your head.  Your feet should be tucked underneath your knees, flat on the floor.

If the seat in front is too far away from you to lean on, bend over and put your arms under your knees, holding onto your forearms.  Alternatively, you can hold your ankles.

Guidelines for infant’s brace position

While holding your baby on your lap, adopt the position as best you can, holding the infant with one arm and making sure that the head is protected.

The rationale for the position

The reasoning behind the brace position is the following.  Having your head against the nearest surface that it would bang into during the landing reduces the possibility of head trauma as the impact is then reduced or eliminated.  Keeping your elbows in reduces flailing (arms being flung around from the force of the landing).

Having your feet tucked beneath your knees, as far back as they will go, reduces the risk of your shins or leg being broken on the base of the seat in front.  With broken shins you cannot escape without assistance.  Broken limbs were a contributory factor in the 1989 Kegworth disaster and Korean Airlines Flight 801.

By placing your arms at the sides of your face it will protect your head from being struck by debris.

Though you might not think it, the tray tables and the seat-backs are constructed of material designed to give some cushioning during impact.

You should not interlock your fingers because if you do that and you are struck by a heavy piece of luggage or debris, you will break all ten fingers.  Then how will you unbuckle your seat belt?  Put your dominant hand on your head and cover it with your other hand.  The changes are that even if some fingers are broken, you will still have the full use of your main hand to unbelt yourself, open the door and other such tasks.

By positioning your head as low as possible you somewhat reduce the risk of being clouted by the overhead baggage racks falling on you – the seats will then take the blow.  If you are over 6 ft in height then you may have difficulty in getting low enough.  Airlines “hate” tall people and big people.

The brace position saves lives

Some have been sceptical about the benefits of the brace position.  Accident investigations have confirmed that the brace position reduces injuries and saves lives.  In particular it reduces possible head trauma and ensures that you can escape from the stricken aeroplane without needing aid.

A good example is that of the emergency landing on the Hudson river by flight US1549 on 15 January 2009.  All 155 passengers on board survived because they experienced no head trauma and could evacuate the plane.  (However, pictures of the passengers standing on the wings with the plane in the river show that only 18 of them used their life-jackets!)

Another instance of the brace position saving lives was Scandinavian Airlines flight 751 which crashed and everybody survived.  Everyone on board had adopted the brace position.

Listen to the safety instructions, read the safety chart, and know how to do the brace position properly.

See also our articles on In-flight safety – hazard awareness and Deep vein thrombosis – protect yourself and Flying when you are ill – what to do