Computers in Aviation Industry -@

8/7/2019 Computers in Aviation Industry -@

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HISTORY OF AVIATION

Determining when computers first took flight depends in part upon one's definition of

a computer. A little more than a decade after the Wright brothers flew at Kitty Hawk,the brilliant U.S. engineer Elmer Sperry adapted gyroscopeswhich consisted of

spinning weights that maintained a specific orientationto electric and pneumaticcontrol systems connected to an airplane's flight controls. This device, soon namedan autopilot, could hold a plane level and on a specific course when the pilot took his

hands off the controls. Over the next several decades, Sperry and others continued

to perfect this technique. The famous Norden bombsight used aboard B-17 and B-29bombers during World War II was a calculating device connected to an autopilot and

controlled the airplane and held it steady when the bombs were released. Thesedevices were all types of computers, although extremely primitive even by the

standards of only a decade or so later.

Aviation history refers to the history of development of mechanical flightfrom theearliest attempts in kitesand glidersto powered heavier-than-air,supersonic and

spaceflights.

Earliest record of the use ofbuoyancy to achieve unmanned flight is as old as the 3rdcentury, when Zhuge Liang used hot air balloonsfor military signaling and to scare away

enemy troops. With the efforts to analyze the atmosphere in the 17th and 18th century,

gases such as hydrogenwere discovered which in turn led to the invention of hydrogenballoons.[1] Various theories in mechanics by physicists during the same period of time

notably fluid dynamics andNewton's laws of motionled to the foundation of modern

aerodynamics. Tethered balloons filled with hot air were used in the first half of the 19thcentury and saw considerable action in several mid-century wars, most notably the

American Civil War, where balloons provided observation during the battle of

Petersburg.

Parachutes and gliders in Umayyad Iberia and England
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Minaret of the Great Mosque atCrdoba. In 852, Ibn Firnas is said to have jumped off

the top in a parachute-like apparatus, and survived with minor injuries.

Islamic Iberiaduring the Umayyad renaissance under the Caliphate of Cordoba witnessedseveral attempts at flight by the Arabpolymathand inventorAbbas Ibn Firnas,[13]

supported by the EmirAbd ar-Rahman II. In 852 he made a set ofwings with clothstiffened by wooden struts. With this umbrella-like apparatus, Ibn Firnas jumped off the

minaret of the Grand Mosque in Cordobawhile he could not fly, his apparatus slowedhis fall, and he escaped with minor injuries. His device is now considered to have been a

prototype of the modernparachute.

Twenty-five years later, at the age of 65, Ibn Firnas is said to have flown from the hill

Jabal al-'arus by employing a rudimentary glider. While "alighting again on theplacewhence he had started," he eventually crashed and sustained injury which some

contemporary critics attributed to a lack of tail.[14][15] His flight may have been an

inspiration forEilmer of Malmesbury, more than a century later, who would fly for about

200 meters using a similar glider (circa 1010).

[16]

Some six centuries after Ibn Firnas, Leonardo da Vinci came up with a hang glider design

in which the inner parts of the wings are fixed, and some control surfaces are provided

towards the tips (as in the gliding flight in birds). While his drawings exist and aredeemed flightworthy in principle, he himself never flew in it. Based on his drawings, and

using materials that would have been available to him, a prototype constructed in the late

20th century was shown to fly.[17] However, his sketchy design was interpreted withmodern knowledge of aerodynamic principles, and whether his actual ideas would have

flown is not known. A model he built for a test flight in 1496 did not fly, and some other

designs, such as the four-person screw-type helicopter have severe flaws.
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Controlling the flight

The 1880s became a period of intense study, characterized by the "gentleman scientists"

who represented most research efforts until the 20th century. Starting in the 1880sadvancements were made in construction that led to the first truly practical gliders. Three

people in particular were active:Otto Lilienthal,Percy Pilcherand Octave Chanute. Oneof the first truly modern gliders appears to have been built by John J. Montgomery; it

flew in a controlled manner outside ofSan Diego on August 28, 1883. It was not untilmany years later that his efforts became well known. Another delta hang-glider had been

constructed by Wilhelm Kress as early as 1877 nearVienna.

The Wright Brothers

The Wrights appear to be the first design team to make serious studied attempts to

simultaneously solve the power and control problems. Both problems proved difficult,

but they never lost interest. They solved the control problem by inventing wing warping

for roll control, combined with simultaneous yaw control with a steerable rear rudder.Almost as an afterthought, they designed and built a low-powered internal combustion

engine. Relying on their wind tunnel data, they also designed and carved woodenpropellers that were more efficient than any before, enabling them to gain adequate

performance from their marginal engine power. Although wing-warping was used only

briefly during the history of aviation, when used with a rudder it proved to be a keyadvance in order to control an aircraft. While many aviation pioneers appeared to leave

safety largely to chance, the Wrights' design was greatly influenced by the need to teach

themselves to fly without unreasonable risk to life and limb, by surviving crashes. Thisemphasis, as well as marginal engine power, was the reason for low flying speed and for

taking off in a head wind. Performance (rather than safety) was also the reason for the

rear-heavy design, because the canardcould not be highly loaded;anhedral wings wereless affected by crosswinds and were consistent with the low yaw stability.

First performances steps under World War I (19141918)

Almost as soon as they were invented, planes were drafted for military service. The first

country to use planes for military purposes was Italy, whose planes made reconnaissance,

bombing and shelling correction military flights during the Italian-Turkish war

(September 1911 October 1912), in Libya. First mission (a reconnaissance) happenedon the 23rd October 1911. First bombing of enemy columns was the 1st November

1911[28]. Then Bulgaria followed this example. Its planes attacked and reconnoitered theOttoman positions during theFirst Balkan War 191213. The first war to see major useof planes in offensive, defensive and reconnaissance capabilities was World War I. The

Allies and Central Powers both used planes extensively.

While the concept of using the aeroplane as a weapon of war was generally laughed at

before World War I[29], the idea of using it for photography was one that was not lost on
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any of the major forces. All of the major forces in Europe had light aircraft, typically

derived from pre-war sporting designs, attached to theirreconnaissance departments.

Technology and performance advances in aviation's "GoldenAge" (19181939)

The years between World War IandWorld War II saw great advancements in aircraft

technology. Aeroplanes evolved from low-powered biplanes made from wood and fabric

to sleek, high-powered monoplanes made of aluminum, based primarily on the foundingwork ofHugo Junkers during the World War I period. The age of the great airships came

and went.

The last quarter of the 20th century saw a slowing of the pace of advancement. No longer

was revolutionary progress made in flight speeds, distances and technology. This part ofthe century saw the steady improvement of flightavionics, and a few minor milestones in

flight progress.

2001 -

In the beginning of the 21st century, subsonic military aviation focused on eliminatingthe pilot in favor of remotely operated or completely autonomous vehicles. Several

unmanned aerial vehicles or UAVs have been developed. In April 2001 the unmanned

aircraft Global Hawkflew from Edwards AFB in the US to Australia non-stop andunrefuelled. This is the longest point-to-point flight ever undertaken by an unmanned

aircraft, and took 23 hours and 23 minutes. In October 2003 the first totally autonomous

flight across the Atlantic by a computer-controlled model aircraft occurred.

Concorde G-BOAB in storage at London Heathrow Airportfollowing the end of all

Concorde flying. This aircraft flew for 22,296 hours between its first flight in 1976 and

its final flight in 2000.

In commercial aviation, the early 21st century saw the end of an era with the retirement

of Concorde. Supersonic flight was not commercially viable, as the planes were required

to fly over the oceans if they wanted to break the sound barrier. Concorde also was fuel

hungry and could carry a limited amount of passengers due to its highly streamlineddesign. Nevertherless, it seems to have made a significant operating profit forBritish

Airways.
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The U.S. Centennial of Flight Commission was established in 1999 to encourage the

broadest national and international participation in the celebration of 100 years of

powered flight.[33] It publicized and encouraged a number of programs, projects andevents intended to educate people about the history of aviation.

COMPUTERS IN AVIATION INDUSTRY:

Just as computers have affected virtually every aspect of modern life, from medicine

to sports to education, they have also had a major impact on aviation. Computersare now used in all parts of aviation. They are used to design airplanes, to control

them in flight, and to ensure that they reach their destinations safely and (more orless) on time.

Determining when computers first took flight depends in part upon one's definition of

a computer. A little more than a decade after the Wright brothers flew at Kitty Hawk,the brilliant U.S. engineer Elmer Sperry adapted gyroscopeswhich consisted of

spinning weights that maintained a specific orientationto electric and pneumatic

control systems connected to an airplane's flight controls. This device, soon namedan autopilot, could hold a plane level and on a specific course when the pilot took his

hands off the controls. Over the next several decades, Sperry and others continuedto perfect this technique. The famous Norden bombsight used aboard B-17 and B-29

bombers during World War II was a calculating device connected to an autopilot andcontrolled the airplane and held it steady when the bombs were released. These

devices were all types of computers, although extremely primitive even by thestandards of only a decade or so later.

Aviation has evolved from simple planes made out of paper and wood to modern airliners

that can carry up to 800 people, with a range of 8200nm, at speeds of up to 450 knots(833 km/h) whilst cruising at 36000ft above the Earth. Computers were, amongst other

things, major contributors to this gigantic evolution: they were used for designing

efficient aircraft with new aerodynamic properties suitable for special roles (military,

commercial etc) but are also used to 'fly' the larger jet airliner aircraft, calculate cruisingaltitudes, speeds, weights, efficiency as well as many other things.

Aircraft during the 1950s and early 1960s also carried analog computers as partof their radar equipment. These were used to provide targeting information for guns

and missiles. The Heads Up Display (HUD) that projected information onto a piece ofglass in front of the pilot relied upon computer input to help the pilot aim his guns or

select his weapons.

Computers at the National Advisory Committee for Aeronautics (NACA) first used

calculating machines in the 1930s to aid researchers in their work, sometimes toperform complicated calculations of airflow over airfoils. Furthermore, wind tunnel

facilities often employed groups of women, who were sometimes referred to as
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"computers," whose sole job it was to perform mathematical calculations concerningairflow.

By the 1950s, as IBM developed better calculating and tabulating machines for office

use, more and more powerful computers were pressed into service to assist innumber crunching the results of wind tunnel tests and in trying to predict some of

the results before actual models were placed into wind tunnels. Computers and windtunnels both had an impact on each other: More powerful computers alloweddesigners not only to process wind tunnel test results better and faster, but to

determine some of those test results before a model was even built, and wind tunneldata allowed designers to develop better programs for their computers to predict

airflow. Computers allowed aircraft designers to narrow their research and test fewerdesigns in wind tunnels than before. By the 1970s, an hour of wind tunnel testing

could cost thousands of dollars, so designers wanted to gain as much data abouttheir aircraft as they could before they ever put a model in a wind tunnel.

By the 1980s, computers had become so powerful that for some applications, theyactually began replacing wind tunnels entirely. This saved tremendous amounts of

money. Aeronautical engineers began developing advanced computer programs toconduct computational fluid dynamics (CFD) experiments. This demand played a

major role in pushing the development of new, powerful, so-called "supercomputers"capable of conducting millions of calculations per second. By the 1990s, computers

had all but replaced wind tunnels for aeronautical research. Furthermore, becausepowerful computers and CFD programs could be bought by any large company

(unlike wind tunnels, which could not be bought from a supplier), commercial aircraftdesigners no longer had to build models to fly in government wind tunnels.

An important early computer, not only for aviation but for computers in general, wasthe Whirlwind computer started at the Massachusetts Institute of Technology (MIT)

in 1944. Whirlwind was a flight simulator. It was the first computer to respondimmediately to actions taken by its operator. Previous computers simply took inputs

and then made calculations and eventually produced an output, sometimes hourslater. But Whirlwind responded in "real time."

As previously noted, the first computers to fly were primitive mechanical devicesused to control planes in flight. Airplane and missile designers kept improving these

systems, which enabled them to do new things. The German A4 (V-2) rocket ofWorld War II used an early computer control system. The Canadian CF-105 Arrow

interceptor airplane, which flew in March 1958, was the first aircraft to use an analogcomputer not as an autopilot but as a means of improving the flyability of the

aircraft. The Arrow's computer was used to reduce the plane's tendency to yaw backand forth in flight. The Apollo Lunar Module also used an analog computer flight

control system and other U.S. spacecraft such as Mercury, Gemini, and Apollo all had

computer flight control systems.

The General Dynamics (now Lockheed-Martin) F-16, which entered service in the late

1970s and has been built in large numbers, was the first operational jet fighter to

use an analog flight control system. The pilot steers the rudder pedals and joystick,but these are not directly connected to the control surfaces such as the rudder and

ailerons. Instead, they are connected to a "fly-by-wire" flight control system. Threecomputers on the aircraft constantly adjust the flight controls to maintain the aircraft

in flight and reply to the commands from the pilot. The F-16 is inherently unstable by


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design, meaning that it would fly out of control if the computers failed (which is whythere are three of them). The designers made it unstable in order to improve its

maneuverability. The computers constantly readjust the flight surfaces to keep theplane flying. Initially, pilots often referred to the F-16 as "the electric jet." But

computer control systems have become so common that they are no longer unusual.

Similar computers were also used on the Space Shuttle and the F-117 stealth fighter.In 1972, NASA tested a modified Navy F-8 Crusader with a digital fly-by-wiresystem, which has replaced analog systems for most applications. Today fly-by-wire

control systems are common on all advanced fighter aircraft. The F-18, F-22, theJoint Strike Fighter, the Eurofighter Typhoon, the Swedish JAS 39 Grippen, and the

French Rafale all use flight control computers.

Although the U.S. Air Force made a major step to adopt computers in its airplanes in

a major way in the 1970s, it took more than a decade before commercial airlinersbegan to adopt them. The MD-11, a highly modified version of the popular DC-10,

was the first commercial aircraft to adopt computer-assisted flight controls. TheAirbus A340 also adopted them. Fly-by-wire has many advantages for small, nimble

aircraft but fewer clear advantages for large, slower ones that rarely reach the edgesof their performance envelope. Because of this, aircraft designers disagree on how

much control should remain with the pilot and how much should be given to acomputer.

The next major area for computers to conquer was the design of aircraft. Designing a

plane such as a large passenger airplane is an immensely complex job involvingthousands of engineers and ultimately hundreds of thousands of pages of blueprints.

Keeping track of all the changes and making sure that workmen are using the latest

blueprints and not outdated ones are major tasks in themselves. In the 1980sBoeing decided to build a new large passenger jet and the program's managers

made the radical decision to design the plane entirely on computers, without usingtraditional paper blueprints. The result was the Boeing 777, which first flew in 1994

and many people referred to as "the first Twenty-First Century Jet."

The latest application of computers is for what is called "the Airborne Internet."

Airplanes will be connected by radio and satellite link to a global information systemthat will provide them with information on the weather and aircraft in their

immediate vicinity, as well as their flight plan.

A modern airliner relies on computers in order to keep it 'flying' which poses a scary

thought: what if these computers fail? Redundancy; airliners may have 2 or more

computers for back-up purposes in case of a, unlikely, failure. Nevertheless, these failuresare, statistically, very rare and computers have made flying much safer than it ever was,

using methods like TCAS (Traffic Collision Avoidance System) which prevents mid aircollisions.

Also, computers are used for 'simulation flying' where pilots can practice their emergencyskills, checklists, operations etc. It is possible for a pilot to have 'zero flight time' in real

life: 100% of his flying has been on simulators and has never flown in real life until

his/her first commercial flight. This means that pilots do not have to fly in a 'real' aircraftto learn how to fly, which is both safer for people (if, for some reason, the aircraft had an


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engine failure in a training flight people on the ground would be put at risk) and is much

more ecological as a simulator does not run on kerosene.

From an Air Traffic Control point of view, computers allow the mass numbers aviationtraffic to pass from country to country at very efficient and safe speeds. It is a common

misconception that the sky is huge and mid air collision are rare; without computers inaircraft systems and air traffic control centres, flying would be very dangerous as there

would be vast amounts of traffic in the same airspace (in the vicinity of a major airport,for example), making collisions highly probable.

Looking at the commercial side of aviation, computers have allowed an uncontrolled

boom in air travel. It is now simpler than ever to book a ticket to almost any part of theworld through a click of a mouse in your home. This has created a, sort of, 'global

network', where anyone can choose where to fly to for holidays.

In conclusion, computers have allowed the evolution of aviation to increase in a veryshort period of time and increase the safety of flying in general.

The ultimate application of computers may be to take over control of flyingcompletely. Already planes can be flown over long distances, with multiple course

changes, entirely by computer. They can also take off and land automatically

(although current flight rules prohibit this). It is not a far step to completelyautomatic operation and pilots may become unnecessary.

Computer Security in Aviation:

Vulnerabilities, Threats, and Risks

An overall system perspective is essential. Security is tightly coupled with safety and

reliability, and must not be ignored or relegated to incidental concerns. We take a broad

view here of the problems of attaining security and safety, and consider these problems asa unified global system/network/enterprise problem.

Security vulnerabilities are ubiquitous. Most computer operating systems have weak

authentication and are relatively easy to penetrate. Most such systems have weak accesscontrols and tend to be poorly configured, and are as a result relatively easy to misuse

once initial access is attained. These systems often have monitoring facilities that are ill

adapted to determining when threats are mounting and what damage may have occurred.Consequently, misuse by outsiders and insiders is potentially easy to achieve and

sometimes very difficult to detect.


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Threats to security and safety are ubiquitous. The range of threats that can exploit

these vulnerabilities is enormous, stemming from possible terrorist activities, sabotage,

espionage, industrial or national competition, copycat crimes, mechanical malfunctions,and human error. Attacks may involve Trojan-horse insertion and physical tampering,

including retributive acts by disgruntled employees or former employees or harassment.

Denial of service attacks are particularly insidious, because they are so difficult to defendagainst and because their effects can be devastating. Systems connected to the Internet or

available by dial-up lines are potential victims of external penetrations. Even systems that

appear to be completely isolated are subject to internal misuse. In addition, many of thoseseemingly isolated systems can be compromised remotely because of their facilities for

remote diagnostics and remote maintenance. Electromagnetic interference is a

particularly complex type of threat. Unanticipated acts of God are also a source of threat

-- for example, from lightning or extreme weather conditions. Of increasing concern inaviation is the omnipresent threat of terrorism.

The risks are ubiquitous. The consequences of these vulnerabilities and associated

threats imply that the risks can be very considerable. Computer-related misuse may (forexample) result in loss of confidentiality, loss of system integrity when systems arecorrupted, loss of data integrity when data is altered, denials of service that render

resources unavailable, or seemingly innocuous thefts of service. Such misuse may be

intentional or accidental. It may be very difficult to detect as in the case of a latent Trojanhorse, or may be blatantly obvious as in the case of a complete system wipeout -- with the

usual spectrum of difficulty in between. More broadly, overall system risks included

major air-traffic-control outages, airport closures, loss of aircraft, deaths of manypassengers, and other major disturbances.

The interrelationships are complex. As stated above, security, safety, and reliability are

closely interrelated, and the interrelationships can be subtle. In general, if a system is notadequately secure, it cannot be dependably reliable and it cannot have any predictableavailability; misuses could happen at any time. Similarly, if a system is not adequately

reliable, it cannot be dependably secure; the security controls could be vitiated at any

time. A simple example of a security-related reliability flaw is provided by the time whenMIT's CTSS (the first time-sharing system) spewed out the entire password file as the

logon message of the day.

A Rev iew o f Pas t Inc identsAmong a large collection of riskful events, many aviation-related cases -- with a widevariety of causes and an enormous range of effects. Two sections in that list are of

particular interest here, namely, those relating to commercial aviation and to military

aviation. We consider here just a few cases from that list.

Radio-frequency spoofing of air-traffic control. Several people have masqueraded asair-traffic controllers on designated radio frequencies (in Miami, in Manchester, England,


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and in Virginia -- the ``Roanoake Phantom''), altering flight courses and causing serious

confusion. (Some communication authentication might help mitigate problems of this

type.)

Power and telecommunication infrastructural problems. Vulnerabilities of the power

infrastructure and other computer problems have seriously affected air-traffic control(Chicago, Oakland, Miami, Washington DC, Dallas-FortWorth, Cleveland, all three New

York airports, Pittsburgh, Oakland, etc.). An FAA report listed 114 major telecomoutages in a 12-month period in 1990-91. Twenty air-traffic control centers were downed

by a fiber-optic cable inadvertently cut by a farmer burying his cow (4 May 1991). The

Kansas City ATC was brought down by a beaver-chewed cable (1990); other outageswere due to lightning strikes, misplaced backhoe buckets, blown fuses, and various

computer problems, as well as a 3-hour outage and airport delays in Boston that resulted

from unmarked electronic components being switched. The AT&T outage of 17September 1991 blocked 5 million calls and crippled air travel with 1,174 flights

cancelled or delayed. Many such cases have been recorded. (Much greater recognition is

needed of the intricate ways in which air-traffic control depends on the power andtelecommunication infrastructures.)

Fatal aircraft incidents. The list of computer-related aircraft accidents is not

encouraging. Undeserved faith in the infallibility of computer systems and the people

who use them played a role in the Korean Airlines 007 shootdown, the Vincennes' Aegisshootdown of the Iranian Airbus, the F-15 shootdowns of two U.S. BlackHawks over

Iraq, the Air New Zealand crash into Mt Erebus, the Lauda Air thrust-reverser problem,

NW flight 255, the British Midlands 737 crash, several Airbus A320 crashes, the

American Airlines Cali crash, the Ilyushin Il-114 crash -- to name just a few.

Near-misses and near-accidents. Numerous near-misses have also been reported, andprobably many more have not. The recent missile observed passing AA 1170 over

Wallops Island reminds us that accidents can be caused by friendly fire (as was indeed

the case in the two UH-60 BlackHawks shot down by our own F-15Cs over Iraq).

Electromagnetic interference. Interference seem to be a particularly difficult type of

threat, although its effects on aircraft computers and communications are still

inadequately understood. Passenger laptops with cable-attached devices appear to be aparticularly risky source of in-flight radiation. EMI was considered as one possible

explanation for the U.S. Air Force F-16 accidentally dropping a bomb on rural West

Georgia on 4 May 1989. EMI was the cited cause of several UH-60 BlackHawk

helicopter hydraulic failures. Australia's Melbourne Airport reported serious effects ontheir RF communications, which were finally traced to a radiating video cassette recorder

near the airport.

Risks inherent in developing complex systems. Computer-communication system

difficulties associated with air-traffic control are of particular concern. Significantproblems have arisen in computer-communication systems for air-traffic control and

procurements for military and commercial aviation and defense systems. Unfortunately,


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these problems are not indigenous to the aviation industry. There have been real fiascos

elsewhere in attempts to develop large infrastructural computer-communication systems,

which are increasingly dominated by their software complexity. For example, theexperiences of system development efforts for the Social Security Administration, the

IRS Tax Systems Modernization effort, and law enforcement merely reinforce the

conclusion that the development of large systems can be a risky business. Anotherexample is provided by the C-17 software and hardware problems; this case was cited by

a GAO report as ``a good example of how notto approach software development when

procuring a major weapons system.'' Unfortunately, we have too many such horrible``good'' examples of what not to do, and very few examples of how systems can be

developed successfully. In general, efforts to develop and operate complex computer-

based systems and networks that must meet critical requirements have been

monumentally unsuccessful -- particularly with respect to security, reliability, andsurvivability. We desperately need the ability to develop complex systems -- within

budget, on schedule, and with high assurance compliant with their stated requirements.

In some aircraft incidents, system design and implementation were problematic; in othercases, the human-computer interface design was implicated; in further cases, human errorwas involved. In some cases, there were multiple causes and the blame can be distributed.

Unfortunately, catastrophes are often attributed to ``human error'' (on the part of pilots or

traffic controllers) for problems that really originated within the systems or that can beattributed to poor interface design (which, ultimately, should be attributed to human

problems -- on the part of designers, system developers, maintainers, operators, and

users!).

There are many common threads among these cases (as well as many dissimilarities),which makes a careful study of causes and effects imperative. In particular, although

most of the cases seem to have had some accidental contributing factors (except for themasqueraders and various terrorist incidents such as the PanAm Lockerbie disaster), andsome cases appear not to be computer related (TW 800), there is much that can be

learned concerning the potential security risks. As we discuss in the following section,

many of the accidentally caused cases could alternatively have been triggeredintentionally.

Poss ib le Fu tu re Inc identsIf accidental outages and unintended computer-related problems can cause this muchtrouble, just think what maliciously conceived coordinated attacks could do --

particularly, well conceived attacks striking at weak links in the critical infrastructure! On

one hand, attacks need not be very high-tech -- under various scenarios, bribes,blackmail, explosives, and other strong-arm techniques may be sufficient; well-aimed

backhoes can evidently have devastating effects. On the other hand, once a high-tech


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attack is conceived, its very sophisticated attack methods can be posted on underground

bulletin boards and may then be exploited by others without extensive knowledge or

understanding. Thus, a high level of expertise is no longer a prerequisite.

Increasingly widespread opportunities for misuse. Everyone seems to be jumping onthe Internet and the WorldWideWeb, with their inherent dependence on software of

completely unknown trustworthiness. The ease with which web pages of the CIA, DoJ,NASA, and the U.S. Air Force have been altered by intruders merely hints at the depth of

the problem. Furthermore, those intruders typically acquired the privileges necessary to

do much greater damage than was actually observed. As air-industry-related activitiesbecome more Internet and computer-system dependent, the risks become ever greater.

One recent example relevant to public transportation is provided by the recent breakdown

of the Amtrak ticket and information system, which on 29 November 1996 brought therail system to its knees; employees had to resort to manual ticketing operations, but with

no on-line schedules and no hardcopy backups.

There are no easy answers. Security, safety, and reliability are separately each verydifficult problems. The combination of all three together is seemingly even more

complicated. But that combination cries out for a much more fundamental approach --

one that characterizes the overall system requirements a priori, carefully controls systemprocurements and developments, enforces compliance with the requirements, and

continues that control throughout system operation. Simplistic solutions are very risky.

Conclusions

Total integration. Security, safety, and reliability of the aviation infrastructure must be

thoroughly integrated throughout the entire infrastructure, addressing computer systems,

computer networks, public-switched networks, power-transmission and -distributionfacilities, the air-traffic-control infrastructure, and all of the interactions and

interdependencies among them.

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