How Airliners Fly E-Book

Julien Evans

• Herausgeber: Crowood
• Kategorie: Lebensstil
• Sprache: Englisch

Veröffentlichungsjahr: 2018

Beschreibung

If you are one of the millions of airline passengers who take to the air daily and have no idea how an aeroplane flies or how it is flown - but would like to find out - then this is the book for you. It is written by an airline pilot who knows from first-hand experience those questions that are asked most frequently. He knows that for many it is an interest born of curiosity, and in some cases, caused by fear. In this revised third edition Julien Evans explains, in straightforward everyday language, about the airframe and the engines, the flight deck and the controls, how the aeroplane is flown and the routines followed. In fact it explains everything the average passenger may wish to know. 'balanced, informative, comprehensive, totally accurate and , most importantly, interesting'.Pilot Magazine.

Leseprobe

HOWAIRLINERSFLY

A PASSENGER’S GUIDE

Julien Evans

Third Edition

First published as Is It on Autopilot? in 1997 by Airlife Publishing, an imprint of The Crowood Press Ltd, Ramsbury, Marlborough, Wiltshire SN8 2HR

www.crowood.com

This e-book first published in 2018

Third edition 2018

© Julien Evans 1997, 2002, 2006 and 2018

All rights reserved. This e-book is copyright material and must not be copied, reproduced, transferred, distributed, leased, licensed or publicly performed or used in any way except as specifically permitted in writing by the publishers, as allowed under the terms and conditions under which it was purchased or as strictly permitted by applicable copyright law. Any unauthorised distribution or use of thistext may be a direct infringement of the author’s and publisher’s rights, and those responsible may be liable in law accordingly.

British Library Cataloguing-in-Publication data

A catalogue record for this book is available from the British Library.

ISBN 978 1 78500 486 5

Dedication

For Christopher and Alison

Photographs by Julien Evans and Ro Phillips except where otherwise notified

Contents

Preface to the Third Edition

Preface to the Second Edition

Introduction

1 The Hardware

2 The Flight Deck

3 How Does it Fly?

4 How Do we Fly it?

5 Performance

6 Navigation

7 The Autopilot

8 The Rules of the Air

9 Radio Communications

10 Meteorology

11 Pre-Flight Preparation

12 Pilot Training

13 When it Goes Wrong

14 The Future

Glossary

Index

Preface to the Third Edition

Since the previous edition of this book was released, there have been further significant developments in the world of airliner operation. In the construction of the airliners themselves, composite materials have replaced aluminium alloy in many parts of their structures, reducing weight without compromising strength. The Airbus A380 has superseded the Boeing 747 as the heaviest airliner in service. The A380’s wings can lift almost 600 tonnes’ total weight. The efficiency of jet engines continues to improve. Despite the remarkable increase of airline traffic in recent years, advances in air traffic control management have further facilitated more direct routing of flights, reducing distance flown between departure and arrival airports. These factors combine to reduce flight time and fuel consumption, with consequent savings in operational costs and – of increasing importance – reduction in environmental impact. Recent improvements in battery technology may lead to the development of electric propulsion in airliners, perhaps in hybrid form initially, with electrically driven propellers or fans augmenting engine thrust.

Compared with earlier years, the flight deck observer in the latest airliner types will note the apparent lack of printed documents and manuals. In keeping with the world at large, the primary sources of information are now data screens. The paper navigation charts, operations manuals and performance manuals of old have all but disappeared from flight decks.

The tasks of the pilots have likewise changed to match the new flight deck environments, except in the most important aspect – the safe and efficient operation of their aircraft. The debate continues, as it has done for the last few decades, as to the degree to which pilots should allow the ever more capable automatic systems to take control. Should aircraft be allowed to fly themselves with minimal pilot input in order to maximize precision and efficiency? Would this policy reduce basic piloting skills, which might be demanded when the automatic systems malfunction, or when circumstances arise that are beyond their capabilities? The human mind brings to the flight deck the element that machines and computers lack – judgement.

Several persons have helped in the preparation of this and earlier editions of How Airliners Fly, and I would like to record my thanks. Captain Ro Phillips was the source of technical and operational information concerning the Boeing 787 and supplied some of the photos of this type. Thanks are also due to Chris Blumenthal, Chris Joseph, Derek Gardner, dave Lawrence, Roger May, Geoff O’Connor, John Rathbone and Roger Setchfield.

The image of the jet engine was kindly supplied by Rolls-Royce, those featuring simulators by CAE Civil Aviation Training and the en route and instrument landing system chart examples by Jeppesen.

Julien Evans, 2018

Preface to the Second Edition

In the few years since the first edition of this book was published (under its original title, Is It on Autopilot?) the technicalities of commercial air transport have continued to develop. On the flight decks of airliners themselves, the presentation of data to pilots is now commonly by video screens rather than the separate electro-mechanical instruments found on older types. To free up airspace as traffic continues to grow, advantage has been taken of air data computer precision to standardize vertical separation between aircraft as 1,000ft in both upper and lower airspace. Improvements in air traffic control computers and greater co-operation between adjoining nations are releasing more aircraft from the constraints of rigidly defined airways, so that more direct routings become available, easing congestion and saving time and fuel.

Likewise, modern navigational equipment has removed the necessity for directional measurement to be referenced to magnetic north; it may well be that geographic north will become the new datum, eliminating the complication of making allowance for the difference between them, which varies from place to place around the world.

Curiously, for a technical industry, aviation has still not adopted standard units when quantifying parameters. Thus distances can be measured in feet, metres, kilometres and nautical miles (and in some countries, statute miles). Speeds are in knots (nautical miles per hour) or metres per second (which is how some countries report wind speed). Masses are kilograms or pounds and air pressure hectopascals or inches of mercury. The one exception to this potpourri of units is that temperature is universally recorded in degrees Celsius. Perhaps in the future aviation will switch to the exclusive adoption of metric measurement, which will obviate the need for personnel in the industry to make conversions – always a possible source of human error. Speeds would be kilometres per hour or metres per second and vertical distance in metres. The current standard 1,000ft vertical separation between aircraft would change to the almost identical 300m.

As commercial air transport moves into its second century, its future is overshadowed by two uncertainties – its vulnerability to terrorist attack and its impact on the environment. The solutions to these problems are primarily the responsibility of the world’s political leaders, although technology will play its part. Today’s jetliners are very much more fuel efficient than their predecessors, and when their seats are filled they can match other methods of people transportation in minimizing environmental damage to our delicate planet. But it may well be that kerosene – cheap and easily produced – will one day become unacceptable as the main propellant for airliners. There are alternatives, which are mentioned in the final chapter of this book, but the travelling public may have to meet the cost of their implementation.

Let us hope that the difficulties can be resolved, so that future generations of pilots and passengers may continue to enjoy the privilege of flight.

Julien Evans, 2002

Introduction

Millions of people travel by air every day. For many of them their only concern is that they depart on time, that the flight is comfortable and that they arrive safely. They will not bother themselves about the technicalities of flight and will take speed and convenience for granted. And why shouldn’t they? Commercial air travel is now a mature industry and passengers’ expectations are high.

For many people, however, aviation is something more than mere transportation. They find fascination and delight in the flight of aircraft of all sorts. They marvel that a machine weighing perhaps 400 tonnes can lift itself into the air and propel itself through the heavens at speeds over 500mph. If they are sitting inside one of them, their curiosity might lead them to ask for permission to visit the flight deck and if they are lucky – and regulations permit – they will be allowed to do so.

What will the flight deck visitor see? Two, or possibly three people, apparently doing very little, surrounded by a bewildering array of display screens, switches and controls. The aircraft will look as if it is flying itself. Certainly no one will seem to be holding the ‘steering wheels’. If the ground is visible, the visitor will perhaps remark that the aircraft appears to be hardly moving. The pilots will explain that the sensation of speed is absent because there is nothing nearby to judge it against, with the aircraft cruising several miles above the earth’s surface. In cloud, or over the sea, or at night, the visitor might naturally ask how the pilots know where they are going. The answer, of course, is that they are not concerned if nothing is visible outside because all the information they need is displayed on the panels in front of them.

The visitor might have other questions. How high are we? How fast are we going? How do you remember what all the switches do? What happens if the engines stop? How long does it take to train as a pilot? How much fuel does it need? What happens if we fly into a storm?

This book is intended to answer questions such as these in language that can be easily understood. Of course, aviation is a highly technical subject, but most people will find that they can grasp the basics without too much difficulty. Although enthusiasts wonder at the capabilities of flying machines, ranging from hang gliders to supersonic fighters to large airliners, the truth is that there is nothing mysterious about them. It is not magic that keeps them aloft, but the laws of nature.

In keeping with its technical background, the language of aviation is peppered with acronyms and abbreviations, not for effect but to ease communication between persons occupied in the industry. In this book I have minimized the use of acronyms where possible and, where they do crop up, I have repeated their full nomenclature from time to time as a reminder. For convenience there is also a glossary. Occasionally, for the sake of clarity, I have oversimplified some technical aspects and taken minor liberties with scientific accuracy. I hope readers disciplined in these subjects will not be offended.

In this book the word ‘pilot’ includes both captains and copilots, whose separate roles will come to light as the text progresses. Given its subject matter, it is understandable that pilots are mentioned more frequently than other personnel in the industry, but they will be the first to admit that no airliner would ever get off the ground without the contribution of the others. Many of these are directly involved with the operation of aircraft, such as cabin crew, engineers and air traffic controllers. Many more have indirect roles to play, including managers, operations staff and ground handling agents. It must be acknowledged that their efforts are no less important than those of the men and women sitting in the pilots’ seats in the flight deck.

On the tricky subject of personal pronouns, I have used the currently favoured ‘he or she’ and ‘him or her’ constructions except where repeated use makes the text clumsy, whereupon I have reverted to ‘he’ and ‘him’, asking the reader to assume the inclusion of the feminine forms by inference. Again I hope this modus scribendi is acceptable to female readers.

Finally, it has to be said that pilots will disagree with the comment above that there is nothing magical about aviation. After all, it was the magic of flight that led them to a career in the skies. And perhaps some readers of this book might themselves feel the same spark and turn their thoughts in the same direction. Who knows, perhaps one day they might find themselves sitting at the controls of a jet airliner, listening to a flight deck visitor asking, ‘Is it on autopilot?’

Chapter 1

The Hardware

THE AIRFRAME

The modern airliner is constructed mainly from aluminium alloy, which is both strong and light. Nowadays some parts of the structure might be made of non-metallic materials, such as carbon fibre composite, which is as strong as aluminium alloy but even lighter. Without its engines, the remainder of the aircraft is referred to as the airframe.

The overall shape of the airliner is determined by aerodynamic factors. Aerodynamics is the study of the behaviour of objects as they pass through the air. What do we need to transport a useful load through the skies? Obviously, the first requirement is a container to hold the load. This container is the called the fuselage and generally takes the form of a cylindrical structure. The front end is its nose and the rear end is its tail.

How do we lift the fuselage and its load into the air? This is the purpose of the wings, which generate the lifting force when air flows past them. At the tail of the fuselage are attached the fin and stabilizer. This assembly strongly resembles the arrangement of tail feathers found on arrows and darts. Indeed, it serves the same function, which is to keep the fuselage pointing in the direction of flight.

In airliners such as the Boeing 787, extensive use of composite materials lightens the aircraft structure.

FIG. 1 The airliner.

Parts of the structure are movable, rather than rigidly fixed. Along the front edge of each wing – the leading edge–are moveable sections called slats. Along the rear edge – the trailing edge – are flaps and ailerons. On the top surfaces of the wings, just ahead of the flaps, are spoilers. The moveable part of the fin is the rudder. The left and right sections of the stabilizer have movable parts called elevators. All these moveable parts are collectively termed the flight controls. They change the airflow patterns around the aircraft and, as the name suggests, they enable the pilot to control the flight path of the aircraft.

We need something to support the aircraft when it is on the ground, and this is the purpose of the landing gear (or undercarriage). In the tricycle arrangement, which is the most common, there are two mainwheel units and one nosewheel unit. Each mainwheel unit is located where the wing joins the fuselage and comprises an assembly of two or four wheels. The mainwheels are fitted with anti-skid brakes. The nosewheel unit is to be found where its name suggests and will typically have two wheels. Nearly the whole mass of the aircraft is borne by the mainwheels. Very large airliners have additional landing gear units. For example, the Airbus A340 has one extra mainwheel unit between the other two, and the Boeing 747 and Airbus A380 have two extra units. These additional wheels spread the load taken by the runways and taxiways on which the aircraft manoeuvre.

The landing gear units are retractable, meaning that they can be folded up into the body of the aircraft once it is airborne. The landing gear is normally retracted immediately after take-off and is extended again during the approach to landing.

Heavier aircraft, such as the Airbus A340, incorporate supplementary landing gear mainwheel units to spread the load borne by the runways and taxiways. The winglets reduce loss of lift at the wing tips.

For greater visibility to other traffic, airliners carry red-and-white flashing lights on their fuselages and wing tips. Powerful landing lights are mounted on the wings and landing gear for illumination of runways and taxiways at night. To comply with night flying regulations, aircraft must also carry other external lights: a red light at the left wing tip, a green light at the right, and rearward-facing white lights.

THE ENGINES

As anyone who has held his or her hand out of the window of a fast-moving car can testify, the air tries to resist the motion of objects passing through it. In aerodynamics, the resistance is called drag. Landing gear is retracted after take-off so that its drag is removed. The purpose of the winglets at the wing tips is to reduce the drag generated by the wings, as will be explained later. The aircraft needs a method of propulsion to overcome the remaining drag and keep pushing it through the air so that the wings continue to generate lift. That propulsive force is provided by the engines. So how does a glider stay aloft if it has no engines? And more to the point, can an airliner continue to fly if all its engines have stopped? We’ll go into this matter later. For the moment, you’ll be delighted to hear that the answer to the latter question is, in general terms, ‘yes’.