POWERED flight in heavier-than-air machines has been with us for more than a century now – but that still doesn’t mean we trust them.

It’s estimated that at least one-in-five airline passengers are really nervous flyers, scared enough to fall into the category that we label the “white knuckle brigade”.

And a whole lot more have smaller, niggling concerns that things might go wrong.

For these people, every little change in noise means that some sort of mechanical failure has occurred.

As the plane speeds along the runway for take-off, those bumps from below and the “ke-plunk, ke-plunk, ke-plunk” convince nervous flyers a wheel is about to fall off, causing the plane crash.

Just as they’ve got over that and they’re safely airborne, there’s a sort of whine and a thud. What’s gone wrong now?

Nothing. Both noises are perfectly normal, and that’s why, as part of fear-of-flying courses, a fair bit of time is spent on explaining to nervous passengers what these noises are.

That bumping on take-off, for example, is most likely the wheels of the plane passing over the centre lights of runways and taxi-ways - exactly the same effect you get when your car strikes cats’ eyes on the road. The second noise is the wheels being retracted and locked in place.

So, what about some of the other sounds people worry about while most of their fellow passengers simply relax?

Although there can be variations between makes and models of aircraft - one set of overhead lockers might shudder and vibrate more than another, or an engine whine might be more penetrating and higher pitched - here’s an explanation of the most common causes of concern.

All that banging and clattering while the plane is still at the boarding gate is the loading of luggage, cargo and food containers, much of it stored in a compartment beneath the floor of the passenger cabins, running on conveyors belts and hitting against stops.

Then doors are closed electronically. That’s another whine, maybe a thump or vibration if you are sitting above them.

For a moment everything becomes still and lights flicker, as if power has been cut. It has.

Until this point, an auxiliary power unit has been providing electricity and running the air-conditioning.

It’s also used to start the engines so, momentarily, air might stop flowing while all available power is used for this operation. Lights might flicker and cabin bells jingle.

The high-pitched screaming that follows means hydraulic pumps are building up pressure, with whirring sounds and whines as pilots check the operation of various parts of the plane.

The look of the wings can be scary. First, they seem to bounce a little. That’s OK - they have to be flexible, with a little give so that they don’t snap off.

But they come apart as well. “Slats” at the front come out and down; “flaps” at the back hang down. This is to permit the shape of the wing to be changed, increasing its curve to provide more lift for take off. You’ll hear a long hum as this happens.

Once at cruising altitude, slats and flaps are retracted, but ailerons at the end of the wings can be moved up or down to help the plane turn.

Spoilers, towards the back edge of the wing, also go up and down, to help provide lift, or act as air brakes.

Roaring and shuddering on take-off is normal because of the sheer power needed, and exhaust from the engines whirls and strikes the fuselage and tail causing vibration.

Chimes are not just used to alert passengers about seatbelts, but also to send signals to the crew: to be seated for take-off or landing, or to perform certain duties prior to landing. The crew may also be using their internal telephone system.

Even during flight, the pilot is making constant adjustments: to maintain course and altitude, changing for weather conditions or the aircraft becoming lighter as it consumes fuel, to fine-tune cabin pressure or temperature. Meanwhile, the cabin crew is rattling around in the galley and passengers are flushing toilets.

Where air traffic is congested, as it is as you come in to land, pilots must manoeuvre more, hence more noises, power being increased or reduced, banking to turn on to another course.

Why bank? It’s the same as a motorcyclist leaning over to go round a corner.

Landing involves doing all these things all over again, with flaps and slats and spoilers and elevators and engine power, with a great thump as the landing gear locks in place.

Tyres squeal on tarmac, followed by a great roar from the engines, as “thrust reversers” deflect the jet engine exhaust forward to create another form of braking.

All that remains now is for the chime that says you can undo your seatbelt.

The Fearless Flier’s Handbook, by Debbie Seaman, published by Ten Speed Press.

QANTAS frequent flyers will be able to use their points in the same way as cash to get any seat on any flight from July 1 as part of a revamp of the airline’s loyalty program.

The airline will also make it easier for its five million frequent flyers to earn points from an expanding range of frequent flyer partners and to burn them on new items such as merchandise and retail vouchers.

The most drastic change will be the addition of a second tier to the loyalty program, to be known as Anyseat, which opens up all seats on Qantas and Jetstar flights.

The new tier aims to remove a bottleneck preventing many frequent flyers booking tickets when they want to fly. But they will pay more for the option and they will not know how much more until they try to book.

Redemptions under the new system will start at about the same points level they are now and rise according to the availability of seats, demand and the time they are flying.

This means travellers will burn more points if they book closer to a flight and fewer if they buy their tickets ahead of time or during quiet periods. A website similar to the Qantas booking engine used by people buying tickets will display how many points a particular seat will cost and give other options on and around that date.

Those wanting to remain with the existing system will do so on a separate “Classic” website.

Qantas Loyalty executive general manager Simon Hickey said yesterday: “Everything that’s there today - all of the value that’s there today, all of those seats, all of that capacity, everything that’s in that program today - none of that changes.

“What we’re doing is adding a lot more choice. So if you want to fly at 7am, Monday morning, Melbourne to Sydney, you can get it now.”

The revamp comes as Qantas separates its frequent flyer operations into a new segment before a partial float expected this year. The airline is believed to be considering an initial public offering this year that would put 40per cent of the program on the market.

Other changes will include the ability to pay for taxes and charges using frequent flyer points as well as more easily use a mix of cash and points to pay for flights.

The airline estimates a return flight from Sydney to London costing 128,000 points in the Classic system will cost about 200,000 points when roughly $700 in taxes and charges are factored in.

The airline plans to make it easier for members to earn points by expanding the number of businesses it counts as frequent flyer partners.

It will introduce new ways of redeeming them for rewards such as holiday packages and retail vouchers for businesses such as supermarkets and department stores. Mr Hickey was optimistic frequent flyers would welcome the changes but admitted that frequent flyer points were an emotive issue.

“I’m adding choice. I’m adding utility value and the ability to use your points in a much greater way,” he said.

V Australia, the international airline of Virgin Blue, and Sabre Travel Network have signed a multi-year distribution agreement that will allow the airline’s fares and inventory to be made available to all Sabre Connected travel agents worldwide, with premium connectivity and electronic ticketing.

V Australia will initially operate flights between the east coast of Australia and the west coast of the US, commencing operations in Dec-08.

Virgin Blue CEO, Brett Godfrey, said “We expect it will be advantageous to early sales penetration in international markets and to delivering significant booking share in key markets in the US and Australia.â€?

The distribution agreement between Sabre Travel Network and Virgin Blue’s V Australia, adds to an already wide-ranging business relationship. Virgin Blue uses many operational solutions from Sabre Airline Solutions including, the AirFlite Suite, AirOps Suite, AirCrews management system and AirMax Revenue Manager, among others.

Australia’s national airline Qantas will increase airfares sold in Australia for domestic and international flights by 3.5 and 3 per cent respectively from May 9.

In an effort to minimise the impact of fuel prices Qantas will reduce overall costs, including a hiring freeze and cutting back on non-essential spending as well as suspending it share buyback program.

The national carrier has stated that while rising fuel prices have been a concern, it remains confident of meeting its guidance for a lift in 2007/08 reported pre-tax profit of at least 40 per cent, from the previous year.

The airline’s low cost offshoot Jetstar is currently reviewing its fare levels. Proposed increases to Qantas fares sold outside Australia are also under consideration.

Qantas chief executive Geoff Dixon said the group’s fuel hedging program, its two brand strategy and efficiency gains from its sustainable future program to had enabled it to manage higher fuel costs to date.

“The continuing rise of jet fuel prices is of concern, however we have hedged 34 per cent of our 2008/09 needs at a price of $US90 ($96) per barrel,” he said.

Qantas said the majority of its hedging is in the first half of the fiscal year and is predominantly in the form of options contracts.

“But if high fuel prices persist beyond this point it would be of increasing concern,” Mr Dixon said.

“An increase in base fares is now necessary to partially bridge the widening gap between the actual increase in the cost of fuel and the amount we offset through surcharges or non-fuel cost improvements,” he said.

“We will continue to monitor fare and surcharge levels and review our network and schedule to optimise capacity.”

Mr Dixon said that due to fuel price volatility the group believed it was prudent to suspend an on-market share buyback program, which began last September.

The group has so far returned more than $500 million to its shareholders.

“We remain confident of meeting our guidance for a 2007/08 result of at least 40 per cent higher than the 2006/07 reported profit before tax,” Mr Dixon said.