CA2114610A1

CA2114610A1 - Airport incursion avoidance system

Info

Publication number: CA2114610A1
Application number: CA 2114610
Authority: CA
Inventors: Peter L. Hoover
Original assignee: Raytheon Co
Current assignee: Raytheon Co
Priority date: 1993-02-26
Filing date: 1994-01-31
Publication date: 1994-08-27
Also published as: NO940625D0; NO940625L; JPH06301898A; EP0613110A1

Abstract

Abstract of the Disclosure An airport incursion avoidance system for detection of aircraft and other vehicles having a sensor co-located with edge lights along taxiways and runways, the sensor output being coupled to a central computer system via the airport's edge light power lines. The detection system comprises infrared sensors. The output of each sensor is fed into a microprocessor within an edge light assembly and then to a power line modem for transmission to the central computer system which includes a display at the airport tower for showing the airport and all traffic thereon. Data from each sensor along taxiways and runways is received at the central computer system and processed to provide vehicle tracking and control of all ground traffic on the airport taxiways and runways to avoid an airport incursion.

Description

2`~1ll613 ~IRPORT I~CURSIO~ ~VOInA~OE S~STE~
Backoround of the Invention This invention relates ~o an airport ground collision avoidance system and in partLcular to an apparatus and method for monitoring, controlling and predicting aircraft i or other vehicle movement primarily on airport taxiways and runways to avoid N nway incursions.
' Currently, ground control of aircraft at an airport is i~
done visually by the air traffic controller in the tower.
~ 10 Low visibility conditions sometime~ make it impossible for ;~ the controller to see all par~s of the field. Ground ¦ su~face radar can help in providing coverage durlng low visibility conditions~ it plays an important part in the lj solution of the runway incursion problem bu~ cannot sol~e -j 15 the entire problem. ~ runway incursion is defined as "any occurrence at an airport involving an aircraft, vehicle, person, or ob~ect on the ground that creates a collision ~ hazard or results~in loss of separation with an aircraft '~t taking off, intending to take off, landing, or intending to land." The U.S. Federal Administration Agency (FAA) has estimated that it can only ~ustify the cost of ground surface radar at 29 of the top 100 airpor~s in the United ~;
States. However; such radar only provides location ~-information; it cannot alert the controller to possible conflicts between aircraft.

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In the prior art, an airport control and monitoring :.
system has been used to ~ense whan an airplane reaches a certain point on a taxiway and controls switching lights on and off to indicate to the pilot when he may proceed on to a ru~way. Such a sys~-e~ sends microwave sensor in~ormation to a computer in the control tower. The computer comprises software for controlling the airport lighting and for ~¦ providing fault information on the airport lighting via l displays or a control panel to an operator. Such a system ¦ 10 is described in sales information provided on a ~i-I directional Series 7 Transceiver (BRITEE) produced by ADB-ALNACO, In~., A Siemens Company, of Columbus, Ohio.
However, such a system doe~ not ~how the location of all vehicles on an airfield and i~ not able to detect and avoid a possible vehicle incursion.
~1 A well known approach to airport surface traffic ;;~ control has been the use of scanning radars operating at `~ high frequencies Yuch a~ K-band in order to ob~ain adequate .~$ definition and resolution. An exi~ting airport ground tra~fic control equipment of tha~ type is known in the art as Airport Surface Detection Equipment (ASDE). However, ~i such eguipment provides surveillance only, no discrete identification of aircraft on ~he ~urface being available.
Al~o there is a need for a relatively high antenna tower and ., 'i 25 a relatively large rotation antenna system thereon.
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Another approach to airport ground surveillance is a system descri~ed in U. S. Patent No. 3,872,474, issued March 18, 1974, to Arnold M. Levine and assigned to International Telephone and Telegraph Corporation, New York, NY, referred to as LOCAR ~Localized Cable Radar) which comprises a series of small, lower powered, narrow pul~es, transmitting radar having lLmited range and time sequenced along opposite sides of a runway ramp or taxiway. In another U. S. Patent No.
4,197,536, i~sued on April 8, 1980, to Arnold M. Levine, an airport surface identification and control system is described for aircraft equipped with ATCRBS (Alr Tra~fic Control Radio Beacon Sy~tem) and ILS (In~trument Landing System). However, these approache~ aro expensive, require special cabling and for identification purposes require expensive eguipment to be included on the aircraft and other vehicles.
Another approach to vehicle identifica~ion such as types of aircraft by identifying the uniquè characteristic of the ~footprint" presented by the configuration of wheels unique to a particular type of vehicle i8 described in U.S.
Patent ~o. 3,872,283, issued ~arch la, 1975, to Gerald R.
Smith et al. and assigned to The Cadre Corporation of Atlanta Georgia. ;~
An automatic system for surveillance, guidance and fire-fighting at airports using infrared ensors is ,~
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described in U. S. Patent No. 4,845,629, issued July 4, 198 to Maria V. Z. Murga. The infrared sensor~ are arranged along the flîght lanes and their output signals are processed by a computer to provide information concerning the aircraft movements along the fligh~ lanes. Position detectors are provided ~or detecting the position of aircraft in the taxiways and parking areas. However, such system does not teach the use of edge light~ along the runwayY and taxiways along with their associated wiring and it is not able to detect and avoid a possible vehicle -incursion.
The manner in which the invention deals with the disadvantages of the prior art to provide a low cos~ airport incursion avoidance 5ystem Will be evident as the lS description proceeds.

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SummarY_of the Invention Accordingly, it is therefore an object of this invention to provide a system that detects a possible aircraft or vehicle incursion at an airport.
It is also an ob~ec~ o~ this invention to pxovide a low cost ai~port incursion avoidance system using edge light assemblies and associated wiring along runways and taxiways.
It is another ob~ect of this inYention to provide an airport incursion avoidance system that ~enerates a graphic display of the airport showing the location of all ground traffic including direction and velocity data.
It is a further ob~ect of this invention to provide an airpor~.incursion avoidance system that generates a verbal alert to an air traf f iC controller or an aircraft pilot.
The ob~ects are further:accomplished by pro~iding an airport incursion avoidance system comprising a plurality .~
of light circuits on an airport, each of the light circuits ;::
comprises a plurality of light assembly means, means for ; .
providing power to each of the plurality of light circuits and to each of the light assembly means, means in each of the light a~sembly means for sensing ground traffic on the airport, means for processing data received from each of the light assembly means, means for providing data communication .
between each of the light assembly means and the processing means, the processing means comprises means for providing a ::
. 5 graphic display of the airport including symbols representing the ground traffic, each of the 3ymbols ha~ing direction and velocity data displayed, the processing means further comprises means for predicting an occurrence of an airport incursion in accordance with the data received from the sensing means, and means for alerting an airport controller or aircraft pilot of the predicted airport incursion. Each of the light circuits are located along the edges of a taxiway or a runway on the airport. The sensing means comprises in~rared detectors. The light a~sembly means comprises light mean~ coupled to the lines of the power providing means for lighting the airport, the in~rared detectors sensing me~ns, microprocessor means coupled to the light means, the sensing means, and the data communication means for providing processing, communication and control for the light assembly means, the microprocessor controlling a plurality of lighting patterns of the light means on the airport, and the data communication means being coupled to the microprocessor means and the lines of the power providing means. The light assembly means further comprises a photocell means coupled to the microprocessor meahs for detecting the light intensity of the light means. The light assembly means further comprises a strobe light coupled to the microprocessor means. The processing means comprises redundant computers for fault tolerance operation. The symbols represen~ing the ground traffic comprise icons having a shape indicating type of aircraft or vehicle. The processing means determines the locations of the symbols on the graphic display of the airport in accordance with the data receive from the light assembly means. The processing means further determines a future path of the ground traffic based on a ground clearance command, the future path being shown on the graphic display. The processing means for predicting an occurrence of an airport incursion comprises means for comparing position, direction and velocity of the ground traffic to predetermined separation minimums for the airport. The power providing means comprises constant current power means for providing a separate line to each of the plurality of light circuits, and network bridge means coupled to the constant current power means for providing a -~
communication channel to the processing means for each line of the constant current power means. The alerting means comprises a speech synthecis unit co~nected to a speaker, ;~
and the alerting means al o comprises a speech synthesis ~;
unit connected to a radio transmitter.
The ob~ects are further accomplished by a method of providing an airport incursion avoidance system comprising the steps of providing a plurality of light circuits on the airport, each of the light circuits comprises a plurality of light assembly means, providing power to each of the plurality of light circuits, sensing ground traffic on the airport with means in each of the light assembly means, processing data received from each of the light asse~bly means in computer means, providing a graphic display of the airport comprising symbol3 representing the ground traffic, .:1 each of the symbol5 having direction and velocity data ~ displayed, providing data communication b2tween the computer j :j means and each of the light a~sembly means, predicting an :j occurrence of an airport incursion in accordance with the data received from the sensing means, and alerting an 1 airport controller or aircraft pilot of the predicted 3 airport incursion. The step of sensing the ground traffic on the airport comprises the ~teps of lighting the airport with a light means coupled to the microprocessor means and ~., the power lines, providing infrared detectors for sensing ;o1 , the ground traffic, performing processing, communica~ion and control within the light assembly means with a microprocessor means coupled to the light means, the sensing means and data communication means, and coupling the data ,~
communication means between the microprocessor means and the power lines. The step of processing data comprises the step .~ of operating redundant computers for ~ault ~olerance. The step of providing power comprises the steps of providing a separate line to each of the plurality of light circuits ~i ~ 2S with a cons~ant current power means, and providing a .,.~
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com~unication channel to.the computer means for each line of the constant current power means using a network bridge means. The step of providing a graphic display comprising symbols representing the ground traffic comprise the step of : 5 indicating a type of aircraft or vehicle with icons of : various shapes. The step of proeessing the data from each of the light assembly means comprises the ~tep of determining a location of the symbols on the graphic display of the airport in accordance with tha data. The step of predicting an occurrence of an airport incursion comprises the step of determining a future path of the ground traffic ;l in accordance with a ground clearance command and showing ~ the future path on the graphic display.

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211~161 0 srief DescriPtion of_the Drawinqs Other and further feature~ of the invention will become ' apparent in connection with the accompanying drawings ,; wherein:
, ,, FIG. 1 is a block diagrEm of the invention of an ~ airport vehicle incursion a~oidance system;
.j FIG. 2 is a block diagram of an edge light as~embly showing a sensor electronics unit coupled to an edge light :~ . of an airfield lighting sy~tem;
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~ assembly showing the edge light positioned above the sensor i';~ electronics unit;
:~ FIG. 4 is a diagram of an airfield runway or taxiway having a plurality of edge light assemblies posi~ioned along each side of the runway or taxiway for detectin~ various size aircraft as shown;
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: 1 FIG. 5 is a block diagram of the central computer system shown in FIG. l;
FIG. 6 shows eleven network variables used in programming the microprocessor of an edge light assembly to interface with a sensor, a light and a strobe light;
FIG. 7 i~ a block diagram showing an interconnection of network variables for a plurality of edge light ass~mblies located on both sides of a runway, each comprising a sensor electronics unit 10 positioned along a taxiway or runway;

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FIGo 8 sho~s a graphic display of a typical taxiway/runway on a portion of an airport as seen by an operator in a control tower, the display showing the location of vehicles as they are detected by the sensors mounted in the edge light assemblies located along taxiways and runways; and FIG. 9 is a block diagram of the data flow within the ., `, system shown in FIG. 1 and FIG. 5.

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: De~criRtion of the Preferred Embodiment Referring to FIG. 1 a block diagram of the invention of ~, an airport vehicle incursion avoidance system 10 is shown ~, comprising a plurality of light circuits 181n, each of said ~ 5 ligh~ cixcuits 181n comprises a plurality of edge light ;1 assemblies 201n connec~ed via wiring 211n to a ligXting . ~
vault 16 which is connected to a central compu~er system 12 ~ia a wide area network 14. Each of the edge light ~, assemblies 201n comprises an infrared (IR) detector vehicle .. 10 4ensor 50 (FIG. 2).
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i The edge light assemblies 20,n are generally located along side the runway~ and taxiways of the airport with an avQrage 100 foot spacing and are interconnected to the , lighting vault 16 by single conductor serie~ edge light ~- 15 wiring 211n. Each of the edge light circuits 181nis powered via the wiring 211n by a constant current supply ~, 24ln located in the lighting vault 16.
. . Referring now to FIG. 1 and ~IG. 2, communication c between the edge light assemblies 201n and the central . 20 computer syste~ 12 is accomplished with LON Bridges 221n interconn~cting the edge light wiring 211~ with the Wide Area Network 14. Information from a microprocessor 44 located in edge light assembly 201n is coupled to the edge light wiring 211n via a power line modem 54. The LON
bridges 221n tran~fers message information from ~he edge ~ . 12 ,~ , ' , " , ' ,: ,,, ', ' ,:, , ' , ..~

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light circuits 181 A via the wiring 211n ~o the wide area network 14. The wide area network 14 provides a transmission path to the central computer system 12. These circuit components also provide the return path communications link ~rom the central eomputer system 12 to the microprocessor 44 in each edge light assembly 201n.
Other apparatus and methods, known to one of ordinary skill in the art, for data com~unication between the edge light assemblies 201n and the central comFuter system 12 may be employed, such as radio techniques, but ~he present embodiment of providing data communication on the edge light wiring 211n provides a low cost system for present airports.
The LON Bridge 22 may be embodied by devices manufactured by Echelon Corporation of Palo Alto, California. The wide area network 14 may be implemented by one of ordinary skill in the art using ~tandard Ethernet or Fiber Di tributed Data Interface (FDDI) componen~s. Irhe cons~ant curren~ supply 24 , ~ , .
may be embodied by devices manufactured by Crouse-Hinds of Winslow, Connecticut.
Referring now to FIG. 2 and FIG. 3, FIG. 3 shows a , ; pictorial diagram of the edge light assembly 201n. The edge ` light assembly 201n comprises a bezel including an `1~ incandescent lamp 40 and an optional strobe light assembly 48 (FIG. 2) which are mounted above an electronics enclosure 43 comprising the vehicle sensor 50. The electronics .~ .
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enclosure 43 8itS on ~he top of a tubular shaft extending t from a ba~e support 560 The light assembly bezel with lamp 40 and base support 56 may be embodied by devices manufactured by Crouse-Hinds of Winslow, Connecticut.
A block diagram of the contents of the electronics ', enclosure 43 is shown in FIG. 2 which comprises a coupling , transformer 53 connected to the edge light wiring 211n. The .~ coupling tran3former 53 provides power to both the :! incandescent lamp 40 via the lamp control triac 42 and the microprocessor power supply 52; in addition, the coupling . transformer 53 provides a data communicatio~ path between the power line modem 54 and the ~ON ~ridges 221n via the edge light wirLng 211~. The microproces~or 44 provides the computational power to run the internal software program that controls the edge light as3emblies 201 n. The microprocessor 44 i~ powered by the microprocessor power supply 52. Also connected to the microprocessor 44 is the lamp control trLac 42, a lamp monitoring photo cell 46, the optional strobe light assembly 48, the ~ehicle sensor 50, and the data communications modem 54. The microprocessor 44 is used to control the inca~descent edge light 40 inten~ity and optional strobe light a~sembly 48. The us~ of the microprocessor 44 in each light assembly 2O1 D allows complete addressable control over every li~ht on the field.
The microprocessor 44 may be embodied by a VLSI device .

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manufactured by Echelon Corporation of Palo Alto, California 94304, called the ~euron~ chip.
Still referring to FIG. 2, the sensor 50 in the present embodiment comprises an infrared ~IR) detector and in other embodiments may comprise other devices such as proximity detectors, CCD cameras, microwave motion detectors, inductance loops, or laser beams. The program in the microprocessor 44 is responsible for the initial filtering of ~he sensor data received from the sensor 50 and responsible for the transmis~ion of such da*a to tha central computer systEm 12. The sensor 50 must perform the following function~: detect a stationa~y ob~ect, detect a moving object, have a range at least half the width of the runway or taxiway, be low power and be immune to false alarms. Thi~ system design does not rely on just one type of sen or. Since sensor fusion functions are performed within the central computer sys~em 12, data inputs from all different types of sensors are acceptable. Each sensor relays a different view of what is happening on the airfield and the central computer system 12 combines them. There are a wide range of sensors that may be used in this system.
As a new sensor type becomes available, it can be integrated into this system with a minLmum of difficulty. The initial sensor used i~ an IR proximity detector ba~ed around a piezoelectric strip. These are the kind of sensors you use ~-- 2 1 ~ a . .
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at home to turn on your flood lights when heat and/or ~; movement is detected. Nhen the sensor output provides an analog signal, an analog-to-digital converter readily known j in the art may be used to interface with the microprocessor 44.
~ Another proximity detector that can be used is based .~ .
~ around a microwave Gunn diode oscillator. These are ;j currently in use in such applications as Intrusion Alarms, ~! Door Openers, Distance Measurement, Collision Warning, ,,j~
Railroad Switching, etc. ~hese types of sensor~ have a drawback because they are not passive de~ices and care needs to be taken to select frequencies that would not interfere with other airport equipment. Finally, in locations uch as ~he hold pocition lines on taxiway~, solid state laser and detector combinations could be used between ad~acent taxiway ."i, ; lights. These ~ensor systems create a beam that when x broken would identify the location of the front wheel of the airplane. This type of detector would be used in those locations where the absolute position of a vehicle was needed. The laser beam would be modulated by the ; microprocessor 44 to avoid ~he detector being fooled by any other stray radiation.
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Referring to FIG. 2 and FIG. 4, a portion of an airport runway 64 or taxiway i~ shown having a plurality of edge light assemblies 201a positioned along each side of the 16 ` -, ~ ! ';
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runway or taxiway for detecting various size aixplanes or vehicles 60, 62. The da hed lines repre~ent the coverage : area of the sensors 50 located in each edge light a~sembly 201a positioned along each side of the runway 64 or taxiway S to insure detection of any ai~plane 60, 62 or other vehicles traveling on such runway 64 or taxiway. The edge light assemblies 201n comprising the sensor 50 are logically connected together in such a way that an entire airport is sensiti~ed to the movement of vehicles. Node to node communication takes place to verify and identify the location of the vehicles. Qnce thi~ i8 done a message is sent to the central computer system 12 reporting the .~, vehicles location. Edge light assemblie~ twithout a sensor ;t . electronics unit 43) and taxiway power wiring currently .,t 15 exist along taxiways, runways and open areas of airports, there~ore, the sensor electronics unit 43 is readily added to existing edge lights and existing taxiway power wiring ,~ .
without the inconvenience and expense of clo~ing down run~ays and taxiways while installing new cabling.
.~ 20 Referring now to FIG. 1, FIG. 5, FIG. 8 and FIG. 9, the :
`.1 central computer syst2m 12 is generally located at a control ;`, tower or terminal area of an airport and is interconnected to the LON Bridge~ 221n located in the lighting ~ault 16 with a Wide Area Network 14. The central computer system 12 comprises two redundant computers, computer #1 26 and ~3 . 17 .~
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~ computer #2 28 for fault tolerance, the display 30, speech ,., synthe~is units 29 & 31, alert lights 34, keyboard 27 and a speech recognition unit 33, all of these elements being interconnected by the wide area network 14 for the transfer ~i 5 of information. The two computers 26 and 28 communicate with the microprocessors 44 located in the edge light assemblies 201n. Data raceived from the edge light assembly 201n microprocessors 44 are used as an input to a sensor :i fusion software modula 101 (FIG. ~) run on the redundant computers 26 and 2B. The output of the sensor fusion software module 101 operating in the computers 26, 28 is ~i used to drive the CR~ display 30 which displays the location .'~ , .
of each vehicle on the airport ~axiway and runways a~ shown in FIG. 80 The central computer system 12 may be em~odied by devices manufactured by IBM Corporation of White Plains, New York. The Wide Area Ne~work 14 may be embodied by devices manufactured by 3Com Corporation of Santa Clara, California. The speech syntheisis units 29, 31 and the speech recognition unit 33 may be embodied by devices manufactured by B~N of Cambridge, Massachusetts. ~-i ; 1 . .
~i The speech synthesis unit 29 is coupled to a speaker 32. Limited infoxmation is sent to the speech synthesis unit 29 via the wide area network 14 to provide the '1 ', capability to give an air traffic controller a verbal alert.
`i 25 The speech synthesis unit 31 is coupled to a radio 37 having i -i 18 .~ .

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an antenna 39 to provide the capability to give the pilots a verbal alert. The voice co~mands from the air traffic controller to the pilots are captured by microphone 35 and sent to the pilots via radio 36 and antenna 38. In the S present embodiment a tap is made and the speech information is sent to ~oth the radio 36 and the speech recognition unit ' 33 which is programmed to recognize the limited air traffic ', control vocabulary used by a controller. ~his includes 3 aixline names, aircraft type, the numbers 0-9, the name of the taxiways and runways and various short phrases such ac ~ "hold shortn, "expediten and "give way to.~ The output of ', the speech recognition unit 33 i3 fed to the computers 26, ,j 28.
'1l Referring again to FI&. 2, the power line modem 54 ',~ 15 provides a data co~munication path over the edge light ~
~1 wiring 211n for the microprocessor 44. This two way path is ~"
-~, used for the'passing of command and control information between the various edge light assemblies 20~n and the central computer system 12. A power line tran~ceiver module in the power line modem 54 i9 used to provide a data channel. These modules use a carrier current approach to create the data channel. Power line modems that operate at carrier frequencies in the 100 to 450 Rhz band are available from many manufacturers. ~hese modems provide digital communication paths at data rates of up to lO,Q00 bits per .~
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,., second utilizing direct sequence spread spectrum modulation.
They conform to FCC power line carrier requireme~ts for ~1 conducted emissions, and can work with up to 55 dB of power .¦ line attenuation. ~he power line modem 54 may ~e embodied `, 5 by a device manufactured by Echelon Corporation of Palo ' Alto, California 94304, called the PLT-10 Power Line Transceiver ~odule.
The data channel provides a transport layer or lowes~
layer of the open system interconnection (OSI) protocol used ~ 10 in the data network. ~he Neuron3 chip which implements the .~ microprocessor 44 contains all of the firmwaxe required to mplement a 7 layer OSI protocol. When interconneeted via an appropriate medium the Neuron~ chips automa~ically !~ communicate with one another using a robust Collision Sense Multiple Access (CSMA) protocol with forward error . corrections, error checXing and automatic retransmission of ~:
missed messages (ARQ).
The command and control in~ormation is placed in data packets and sent over the network in accordance with the 7 Layer OSI protocol. All messages generated by the ~ microprocessor 44 and de~tined for the central computer `~ system 12 are received by the network bridge 22 ~ia the .~ power lines 211n and routed to the central computer system `~ 12 over the wide area network 14.

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The Neuron~ chip of the microprocessor 44 comprises three processors (not shown) and ~he firm~are required to support a full 6 layer open systems interconnection (OSI) protocol. The user is allocated one of the processors for the application code. The other two processors give the application program access ~o all of the other Neuron~ chips , in the network~ This acce~s creates a Local Operating Network or LON. A LON can be thought of as a high level local area network LAN. The use of the Neuron chip for the implementation of this invention, reduces the amount of ; ; custom hardware and software that otherwise would have to be `, developed. ;
Data from the sensor electronic unit 43 of the edge `~ light assemblie~ 201n is coupled to the central computer ~i, 15 system 12 via ~he existing airport taxiway lighting power `~ wiring 21. Using the existing edge light power line to transfer the sensor data into a LON network has many advantages. Asi previously pointed out, the reuse of the existing edge lights eliminates the inconvenience and expense of closing down runways and taxiways while running .i , new cabl~ and provides for a low cost system.
~-~ The Neuron chip allows the edge light assemblies 201_n to automatically communicate with each other at the applications level. This is accomplished through network ~ 25 variables which allow individual Neuron9 chips to pass data `l 21 ~,~

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2 ~ 1610 between themselves. Each ~euron~ ~C~ program comprises both local and network variables. The local Yariables are used by the Neuron~ program as a scratch pad memory. The network j variables are used by the Neuron program in one of two ways, either a a network output variables or a network input variahles. Both kinds of variables can be initialized, evaluated and modified locally. The difference , comes into play in that onc~ a ne~work output variable i~
modified, network messages are automatically sent to each network input variable that is linked to that output variable. This variable linking is done at installation time. As soon as a new value of a ne~work input ~ariable is received by a Neuron~ chip, the code is vectored off to take appropriate action based upon the value of the network input variable. The advantage to the program is that this message pas~ing scheme is entirely transparent since the message pas~ing code is part of the embedded ~euron~ operating system.
Referring now to FIG. 6, eleven network variables have been identified for a sensor program in each microprocessor :1 ' .
44 of the edge light as4emblies 201n. The sensor 50 ;,` function has two output variables: prelim detect 70 and ~ confirmed detect 72. The idea here is to have one output ;~ trigger whenever the sensor 50 detects movement. The other ;~1 25 output does not trigger unless the local sensor and the ~ii 22 :
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, sensor on the edge light across the runway both ~pot movement. Only when the detection is confirmed will the signal be fed back to the central computer system 12. This techni~ue of confirmation helps to reduce fal~e alarms in order to implement this technique the ad~acent sensor 50 has ;~ a~ input variable called ad~_prelim detect 78 that is used ~ to receive the other sensors prelim dstect output 70. Other .~
input variables are upstream detect 74 and downstream detect , 76 which are used when chaining ad~acent sensors together.
'i 10 Also needed is a detector sensiti~ity 80 input that is used ~' by the central computer system 12 to control the d~tection ~ ability of the sensor 50.
i~ The incandescent light 40 requires two network ` variables, one input and the other an output variable. The input variable light le~el 84 would be used to control the ~ light~s brigh~ness. The range would be OFF or 0% all the ;~ way to FULL ON or 100%. This range from 0~ to 100% would be ; made in 0.5~ steps. Since the edge light assembly 20~n also , contains the photocell 46, an o~tput variable light failure 84 is created to signal that the lamp did not obtain the desired brightness.
The strobe light 48 requires three input variables.
The stxobe-mode 86 variable is used to select either the OFF, SEQUENTIAL, or ALTERNATE flash modes. Since the two flash modes require a distinct pat~ern to be created, two ~`.J
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-, input vari,~bles active_delay 88 and fla~h delay 90 are used I to time align the strobe flashes. By setting these individual delay factors and then addressing the Neuron~
chips as a group, allows the creation of a field strobe pattern with 1,ust one command.
, ., -1 ~eferring now to FIG. 7, a block diagr,~m of an ~ interconnection of ne~work variables for a plurality of edge $~ light ass~smblies 201n located on both sides of a runway is i shown, each of the edge light as~s~,~mblies 20~n comprising a ., 10 microprocessor 44. Each Ne,uron~ program in the :/ microprocessor 44 is designed with certain network input and '1l output variable3. The user~writes the code for the Neuron ~ chips in the microprocei~or 4~, a3suming that the input3 are, `.'! su~,plied and that the outputs are used. To create an actual i .~
network the user ha~ to ~wire up~ the network by ~ interconnecting the indiYidual nodes with a software ;`1 linker. The resulting di~stributed process is best shown in -~1 schematic form, and a portion of the network interconnect ~ 1 .:`, matrix is shown in Figure 7. The prelim_detect 70 output of ~, 20 a sensor nod,e 44~ i5 connected to ~he ad~, Primary detect 92 input of the sensor node 44, across the taxiway. T~i3 is ;~:
`~ used as a means to verify actual detections and eliminate false reports. The communic~tions link between these two ~, !
`~ node~ 441 and 44~ is part of the distributed processing.
The two nodes communicate ,among themselves without involving :` 24 ~ :~

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the central computer system 12. If in the automatic mode or if instructed by the controller, the system will al50 alert ;~) the pilots via audio and visual indicatlons.
~ Re~erring again to FIG. 1 and FIG. 4, the central `1, 5 computer system 12 tracks the movement of vehicles as they pass from the sensor 50 to sensor 50 in each edge light assembly 201n. Using a varia~ion of a radar automatic track algorithm, the sy~tem can track position, velocity and heading of all aircraft or vehicles based upon the sensor 50 readings. New vehicles are entered into the system either 1 upon leaving a boarding gate or landing. Unknown vehicles are also tracked automaticaIly. Since taxiway and runway lights are normally acro~s from each other on the pavement (as shown in FIB. 4 and FIG. 7), the microprocessor 44 in each edge lights assembly 201n i~ programmed to combine their sensor 50 inputs and agree before reporting a contact.
A further refinement is to have the microprocessor 44 check with the edge light assemblies 20~n on either side of them to see if their sensors 50 had detected the vehicle. This allows a vehicle to be handed off from sensor electronic ~;i3l unit 43 ~o sensor elec~ronic unit 43 of each edge light~i assembly 20~n as it travels down the taxiway. This alsoas~ures that ~ehicle position reports remain consistent.
~l Vehicle velocity may also be calculated by using the `~ 25 ~~ .

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, ' `~ dictance between sensors, the sensor pattern and the time between detec~ions.
Referring to FIG. 5 and FIG. 8, the display 30 is a color monitor which provides a graphical display of the airport, a portion of which is shown in FIG. 8. This is ~i accomplished by storing a map of the airport in the redundant compu~ers 26 and 28 in a digital format. The display 30 shows the location of airplane~ or vehicles as ,3j they are de~ected by ~he sensors 50 mounted in the edge `i, 10 light assemblies 201n along each taxiway and runway or other , . ~
i airport surface area~. All aircraft or vehicles on the airport surface are displayed as icons/ with the shape of the icons being determined by the vehicle type. Vehicle ~, position is shown b~ the location of the icon on the screen.
Vehicle direction is shown by either ~he orientation of the icon or by an arrow emanating from the icon. Vehicle status ~ is conveyed by the color of the icon. The future path of ``d the vehicle as provided by the ground clearance command ;' entered via the controllsrs microphone 35 is shown as a colored line on the display 30. The sta~us of all field ~! lights including each edge light 201n in each edg~ light circuit 181n i~ shown via color on the display 30.
Use of ob~ect orientated software provides the basis for building a model of an airport. The automatic i ` :
inheritance feature allows a data structure to be defined . ~.

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once for each object and then replicated automatically for each instance of that ob~ect. Automatic flow down assures that elements of the data base are not corrupted due to . typing errors. It also assures that the code is regular and structured. Rule based ob~ect orLented programming makes it difficult to create unintelligible ~spaghetti code. N Ob~ect oriented programming allows the runways, taxiways, aircraft and sensors, to be decoded directly as ob~ect~. ~ach of these ob~ects contains attributes. Some of these attributes are fixed like runway 22R or flight UA347, and some are ~, variable like vehicle status and position.
In conventional programming we describe the attributes of an ob~ect in data struc~ure~ and then describe the behaviors of the ob~ect as procedures that operate on those data structures. Object oriented programming shifts the emphasis and focuses first on the data structure and only secondarily on the procedures. More importantly, ob~ect oriented programming allows us to analyze and design programs in a natural manner. We can think in terms of runways and aircraft instead of focusing on either the behavior or ~he data structures of the runways and aircraft.
Table 1 shows a list of objects with corresponding attributes. Each physical ob~ect that is important to the runway incursion proble~ is modeled. The basic airplane or vehicle tracking algorithm is shown in Table 2 in a ProgrEm r~, .;~ .

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Design Language (PDL). The algorithm which handles sensor fusion, incursion avoidance and safety a~erts is shown in a ! 1 .
`i single program even though it is implemented as distrlbuted ' system using ~oth the central compu~er Rystem 12 and the ;~! 5 sensor microprocessors 44.
" ~rABr~ 1 C~LnUCS ATTRIBU~ D~sr$LcprTc~
! Son~or ~ocatlon X ~ Y coordin~tes of ~on~or I Circuit AC wlrlng oircult naru ~ numbor ', 1 0 Uniquo addro~u ~ot ~ddreau ror this ~en~or ~nd lt~ ~nte ~i L~mp_intonsitr 0~ to 100~ ln 0 5~ ~tsp~
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S~robo_st~tu- Blin~ r~te~off i Strokc-dal~y ~ro~ start slgn~
Sonsor st~tus Dctect/no datact Son~or_typo IR, lo-~r, ~ro~cimity, otc ;1 Runw~y Nnmo 22R~ 27, 33L, otc ~oc~tion Y ~ Y coordln~tes of atnrt of center line -~ Length In i'e-t ~;1 Wldth ~n reot Directlon ~n degre~s from north Status Not ~ctivo, ~ctlvn takeoff, ~ctlve lnndlng, ~l~r~
~i Son~ora ~V) ~iat of llght~/3enaor~ ~long thlg runw~y ~`
Intersectlon~ t~V~ Llst oS intora-ctlon~
~, Vehlclos Ll~t o~ vohlclos on the runw~y T ~ lw~y Namo Namo of t~clwlly ~ocatlon X ~ Y coordln~tes of st rt of center llno ~ongth In foot Wldth ~n foet Dlroctlon In dogroos from north Stiltus Not ~ctlve, Actlvo~ ~lBnn `~ Sonsor~ ~V~ t of lntarsootlons `~ Bold Loc~tlon~ Ilst of holding loc~tlon~

~I Vahlclo- ~V) Li~t of vehlclo~ on tho runw~y , .
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Ihter6ection Na~ I~ter-~ctlon N~m~
LocAtion Int~rs~Ctiqn o2 two c~nter lines StAtU- V~ic_At/Occupiod Sensor~i ~MV) Ll-t o~ sun-o~ cr~tln~ lnt~rssction ~ord~r l 5 Air~r~t Airlino Unit-d '~¦ Mod-l 727-200 ~all-nu~b~r N3274Z
i ~mpty w-ight 9 5 tone ~ Fraight w~ight 2.3 ~on~
"1 0 Fuel woight 3 2 tons Top ~&d 59a ~ph ~,~ Vl Lpood 100 ~ph VZ_ p-~d 140 m~h Accel~ration 0.23 g' 9 t 15 Doce~l~r_tion 0.34 9~L
~l ~V - Hulti-vAriDblo or ~rrAiy .~ Table 2 while (forev~rl if ~edge light ahows a detsctLon) ¦ ¦ if ~adjacent light also ~how~ a detection senaor fu~ion) ¦ ¦ ¦ /* CONFI N D DETECTION */
.,, ¦ ¦ ¦ $~ ~prev$oua bIock showed a det~ction~ :
¦ ¦ ¦ ¦ /* ACC$PT ~ANDOFF ~/
¦ Ujpdate aircraft position asid apead 1 1 1 el~e ~AY BE i~N aNI~A~ OR SE~V~ OE TRUC~ ~/
¦ ¦ ¦ ¦ Al2rt operator to pos~ible lnaurslon ~ /* MAY BE AN AIRCRAFT ENTERING T~B SYSTE~i */
`:i I I I I Start a n~w track .~ 30 ¦ I else ¦ ¦ ¦ Regyeat ~tatua from adjac~nt light if ~Adjacant llght i~ OX) . 29 ., ;~ , .
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¦ /* NON CONFIRM~D D~TECTION ~/
eilEie ¦ ¦ ¦ ¦ Flag adjacent light for repair ¦ ¦ endif 1 ¦ endif ` ¦ eindif ¦ lf ~Edge light loEie~i a detaction ANr ~tatuEi i,s OR) ¦ ¦ lf ~N~xt block ~ihowed a detection) * PROPER HANDOFF */
1 1 el~e ~-~. ¦ ¦ ¦ if ~vehicle Eipeed > ~ takeoff) ¦ ¦ .¦ ¦ Handoff to departurei control el~ie ¦ ¦ ¦ ¦ /* MISSING ~ANDO~F ~/ -¦ ¦ ¦ ¦ AlQrt operator to po3~iibla incur~iion . I I I endif ¦ ¦ endif l ¦ endL~
-i ¦ /* CHECR FOR POSSTBLE COLLTSIONS */
¦ for ~all tracked aLrcraft) Plot future po~ition lf ~position conflict) Alert operator to po~ible incursion ¦ ¦ endif ~5 ¦ endif ~:
Update di~play ~-~
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Referring again to YIG. 1 and FIG. 2, the control of taxiway lighting intensity is usually done by placing all the lights on ~he same serie~ circuit and then regulating ,~
,' the current in that circuit. In the present embodLment the i 5 intensity of the lamp 40 is controlled by 3ending a message ~ with the light intensity value to the microprocessor 44 ;~ located within the light as~embly 201n. The message allows ~or intensity set~ings in the range of 0 to 100~ in 0.5%
steps. The use of photocell 46 to che~k the light output ' 10 allows a return message to be sent if the bulb does not ; respond, This in turn generates a maintenance report on the ~'~ light. The strobe light 48 provide~ an additional optional i :
~,~ capability under progri~m control of the microproces~or 44.
Each of the microprocessors 44 in the edge li~ht assemblies 20 is ~ndividually addressable. This mean~ eYery lamp on the field is controlled individually by the central computer ~ system 12.
;~ The system 10 can be progrEmmed to provide an Active ~ Runway Indicator by using the strobe lights 48 în tho~e edge ,~ 20 light assemblies 20,~ located on the runway 64 to continue ~ the approach light ~rabbit~ strobe pattern all the way down ;, the runway. This lighting pattern could be turned-on as a ~ plane is cleared for landing and then turned-off after the .
aircraft has touched down. A pilot approaching the runway ,,1 ~ 25 along an intersecting taxiway would be alerted in a clear ,~
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, ~ 1 ; and unambiguous way that the runway was active and should not be crossed.
If an incursion was detected the main computers 26, 28 could switch the runway strobe lights 48 from the ~rabbit~
patterr. to a pattern that alternatively flashes either side of the runway in a wig-wag fashion. A switch to this pattern would ~e interpreted by the pilot of an arriving aircraft as a wave off and a signal to go around. The abrupt switch in the pattern of the strobes would be instantaneously pi~ked up by the air crew in time for them to initiate an aborted landing procedure.
During Category III weather condition~ both runway and taxiway visibility are very low. Currently radio based landing ~y~tem~ are used to get the aircra~t from final . . .
approach to the runway. Once on the runway it is not always ob~iou3 which taxiways are to be used to reach the airport terminal. In system 10 the main computers 26,28 can control ~ the taxiway lamps 40 as the means for guiding aircraft on ;~ the ground during CAT III conditions. Sincs the intensity 1 20 of the taxiway lamps 40 can be controlled remotely, the `~1 lamp~ ~u~t in front of an aircraft could be intensified or 1 . ~
flashed as a means of guiding it to the terminal.
Alternati~ely, a short sequence of the "rabbit" pattern may be programmed into the taxiway strobes ~ust in ront of the aircraft. At intersections, either the unwanted paths ~-"
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may have their lamp3 turned off or the entrance to the ~;~ proper section of taxiway m;~y flach directing ths pilot to head in that direction. of course in a smart system only those lights directly in front of a plane would be controlled, all other lamps on the field would remain in ~ their normal mode.
;I Referring now to FIG. 9, a block diagram is shown of the data flow within the system lO (as shown in FIG. 1 and FIG. 5). The software modules are ~hown that are used to ;`'~ lO process the data within the computers 2~, 28 of the central ~ . computer ~ystem 12. The ~racking of aircraft and other ,.~
vehicles on the airport operates under the control of a sensor fusion software module 101 which re~ides in the -computers 26, 28. ~he sensor fusion softwar~ module lO1 ~ 15 receives data from the plurality of sensor~ 50, a sensor 50 r'~ being located in each edge light asse~bly 201n which reports the heat level detected, and this software module lOl combine this information through the use of rule based artificial intelligence to create a complete picture of all ,,~a, 20 ground traf~ic at the airport on a display 30 of the central computer sy~tem 12.
The tracking algorithm starts a track upon the first I
xeport of a sensor 50 detecting a heat level that is above the ambient background level of radiation. This detection is then verified by checking the heat level reported by the ;;
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sensor ~irectly across the pavemant from the first reporting sensor. This secondary reading is used to confirm the vehicle detected and to eliminate false alarms. After a vehicle has been confirmed the sensors ad~acent to the first reporting sensor are quer1ed for changei in their detected heat level. AS soon a~ one of the ad~acent i3ensors detects a rise in heat level a direction vector for the vehicle can ! ' be established. Thi~ proceRs continues as the vehicle ii~ -handed off from sensor to sensor in a bucket brigade fa~hion a~ shown in FIG. 7. Vehicle speed can be roughly dztermined by calculating the time between vehicle detection by ad~acent ~ensors. Thiii information is combined with information from a ~ystem data ba~e on the lccation of each sensor to calculate the velocity of the target. Due to hot ' 15 exhauit or ~et bla~t, the sensox~ behind the vehicle may not -~
-, return to a background level immediately. ~ecause of the e `~ condition, the algorithm only u~es the first four sen~ors (two on either side of the taxiway) to calculate the vehicles position. The vehicle is alway-~ assumed to be on 0 the centerline of the pavement and between the first four reporting sen~or~.
Vehicle identification can be added to the track either manually or automatically by an automated source that can identify a vehicle by it~ position. An example would be ' 25 prior knowledge of the next aircraft to land on a particular , " , . . . .

2 ~
., runway. Track~ are ended when a vehicle leaves the detection system. This can occur in one of two ways. The first way is that the vehicle leaves the area covered by the sensors 50. This is determined by a vehicle track moving in the direction of a gateway sensor and then a lack of ~' detection after the gateway sensor has lost contact. A~', second way to leave the detection sys~em is for a track to be lost in the middle of a ~ensor array. This can occur when an aircraft departs or a vehicle runs onto the grass.
Takeoff scanarios can be determined by calculating the speed ,j of the vehicle ~ust before detection wai~ lost. If the~,i vehicle speed was increasing and above rotation speed then J the aircraft is assumed to have taken off. If not then the vehicle i~ assumed to have gone on to the grass and an alarm l 15 is sounded.
Referring to FIG. 5 and FIG. 9, the ground clearance routing function is performed by the speech recognition unit 33 along with the ground clearance compliance verifier software module 103 running on the computers 26, 28. This software module 103 comprises a vehicle identification routine, clearance path routing, clearance checking routine and a path checking routine.
The vehicle identification routine i~ used to receive the airline name and flight nu~ber (i.e. ~Delta 374~) from the speech recognition unit 33 and it highlights the icon of ' ~ 35 "' . ,- ~ ` ' ~ ` - : :
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that aircraft on the graphic display of the airport on display 30.
The clearance pa~h routine takes the remainder of the controller~s phrase (i.e. nouter taxiway to echo, hold short of runway 15 Left~) and provides a graphical display of the clearance on the display 30 ~howing the airport.
The clearance checking routine checks the clearance path for possible conflict with other clearances and vehicles. If a conflict is found the portion of the path that would cause an incursion is highlighted in a blinking red and an audible indication is given to the controller via speaker 32.
~ The path checking routine checks ~he actual path of the 3 vehicle as detected by th~ sensors 50 after the clearance path has been entered into the computers 26, 28 and it ~1 -~ monitor~ the actual path for any deviation. If this routine detects that a vehicle has strayed from the as~igned cour~e, the vehicle icon on the graphic display of the airport ~ flashes and an audible indicator is giYen to the controller -j 20 via speaker 32 and optionally the vehicle operator ~ia radio 37.
The airport vehicle incursion avoidance system 10 operates under the control of safety logic routines which reside in the collision detection software module 104 l~ 25 running on computers 26, 28. The safety logic routines `s 36 `i A, ,: i , . ~, , 2 ~
~ receive data from the sensor fusion software module 101 via .~
the tracker software module 102 location program and 1 interpret this information ~hrough the use of rule based . .~
3 . artificial intelligence to predict possible colli~ions or ru~way incursions. This information is then used by ~he central computer system 12 to alert tower controllers, 3 aircraft pilots and truck opera~or~ to the posaibility of a runway incursion. The tower controllers are alerted by the di~play 30 along with a computer synthesized voice message via speaker 32. Ground traffic is alerted by a combination of ~raffic lights, flashing light~, stop bars and other alert li~hts 34, 1amp8 40 and 48, and computer generated voice ~ommand~ broadcast via radio 36.
Knowledge ba~ed problem~ are also called fuzzy problems and their solution~ depend upon both program logic and an interface engine that can dynamically create a decision tree, selecting which heuristics are most appropriate for the specific case being considered. ~ule based systems broaden the scope of possible applications. They allow designers to incorporate ~udgement and experience, and to take a con~istent solution approach acros~ an enti~e problem ~ set.
`~ The progrEmming of the rule based incursion detections software is very straight forward. The rules are wIitten in English allowing the experts, in this case the tower ., ~ .
~ 37 .-- .

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; personnel and the pilots, to re~iew the ~ystem at an under~tandable level. Another feature of the rule based system is that the rules ~tand alone. ~hey can b~ added, deleted or modified without affecting the rest of the code.
Thi~ is almost impossible ~o do with code that iB created from scratch. ~n example of a rule we might use is:
I~ (Runway StatuR = ActLva) ~ then (stop Bar ~ight~ - ~ED).
;' This is a very simple aIld straight forwaxd rule. It stands alone requiring no extra knowledge except how Runway Statu3 i9 cr~aated. So let's make 60me rule~ affecting .,! .
Runway Status.
If (Departuro ~ APP~OVED) or (7a~ding ~ INMINEN$), then (Runway tatu~ ~ ACTIVE).
For incursio~ detec~ion, another rule is:
¦ If (Runway Status ~ ACTIVE) and (Interg~ction a OCCUPI~D)``i then (Run~ay Incur3ion 3 TRUE).
Next, detect that an inter~ection of a runway and taxiway ~¦ are occupied by the rules:
If ~Intar~ectlon S~n~or~ 8 DETECT), then (Inter~ection - OCCUPI~D).
To predict that an aircraft will run a Hold Position stop, the following rule i~ created:
If (Aircraft Stopping Di~tance ~ Di~tance to ~old? osi~ion), then (Int3rseotion - OCCUPI~D).

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In order to show that rules can be added without affecting the reset of the progriam, assume that after a demonstration of the system 10 to tower controllers, they decided that they wanted a ~Panic Button~ in the tower to ; ~
override the rule ba ed software in case they spot a safety violation on the ground. Be~ides installing the button, the only other change would be to add this extra rule.
If ~Pi3nic: button - PRESSED), then ~Rtmway Incur~ion - TRUE).
It is readily seen that the central rule baæed computer ; program is very straight forward to create, under~tand and J modify. As types of incursions are defined, the sy~tem 10 can be upgraded by adding more rules.
Referring again to PIG. 9, the block diagram shows the data flow between the functional elements within the ~ystem -~
lQ (FIG. 1). Vehicles are detected by the sensor 50 in each of the edge light assemblies 201n. This information is passed over the local operating netw~rk (LON) via edge light wiring 211n to the LON bxidges 221n. The individual message packets are then passed to the redundant computers 26 and 28 over the wide area network (WAN) 14 to the WAN interface 108. ~ter arriving at the redundant computers 26 and 28, tha message packet is checked and verified by a mes~ags parser software module 100. The contents o~ the message are then sent to the sensor fusion xoftware module 101. The ~3 ~
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sensor fu~ion software module 101 is used to keep track of the status of all the sensors 50 on the airport; it filters and verifies the data from the airport and ~tores a representative picture of the sensor array in a memory.
This information is used directly by the display 30 to show which sensors 50 are responding and used by the tr2cker l software module 102. The tracker software module 102 uses :~ the sensor status information to determine which sensor 50 report~ corre~pond to actual vehicles~ In addition, as the sensor reports and status change, the tracker software module 102 identifies movement of the vehicles and produces a target location and direction outpu~. This information is l used by the display 30 i~ order to display the appropriate -j vehicle icon on the screen.
::l 15 The loeation and direction of the vehicle is also used ~ by the collision detection software module 104. Thi~ module .~ checks all of the vehicles on the ground and plots their expected course. If any two targets are on intersecting paths, this software module generates operator alerts by ~ 20 using the display 30, the alert lights 34, the speech J' synthesis unit 29 coupled to the associated speaker 32, and the speech synthesis unit 31 coupled to radio 37 which is :~
coupled to antenna 39.
i Still referring to FIG. 9, another user of target l~ 25 locatio~ and position data is the ground clearance ~

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compliance verifier software module 103. This software module 103 receives the ground clearance command from the controller~s microphone 35 via the speech recognition unit 33. Once the cleared route has been determined, it is S stored in the ground clearance compliance verifier software module 103 and used for comparison to the actual route taken by the vehicle. If the information recei~ed from the tracker software moduls 102 shows that the vehicle has deviated from its assigned courss, this ~oftware module 103 ~ 10 generate~ operator alerts by using the display 30, the alert ;i lights 34, the speech synthesis unit 29 coupled to speaker 32, and the speech synthesis unit 31 coupled to radio 37 which is coupled to antenna 39.
~, The keyboard 27 i connected to a keyboard parser '`d 15 software module lO9o When a command has been ~erified by the keyboard parser software module 109, it i~ used to change display 30 options and to reconfi~ure the sensors and network parameters. ~ network configuration data ba~e 106 `~
`~ is updated with these reconfiguration commandc. This information i~ then turned into LON message packets by the ~ command message generator 107 and sen~ to the edge light ``, assemblies 2O1 D via the WAN interface 108 and the ~ON
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)l bridges 221~.
This conclude~ the description of the preferred embodiment. ~owever, many modifications ~nd alterations .
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will be obvious to one of ordinary skill in the art without departing from the spirit and scope of the inventive concept. Therefore, it is in~ended that the scope of this invention be limited only by the appended claims.

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Claims

1. An airport incursion avoidance system comprising:
a plurality of light circuits on an airport, each of id light circuits comprise a plurality of light assembly ans;
means for providing power to each of said plurality of ?ght circuits and to each of said light assembly means;
means in each of said light assembly means for sensing ground traffic on said airport;
means for processing data received from each of said ?ght assembly means;
means for providing data communication between each of ?id light assembly means and said processing means;
said processing means comprises means for providing a ?aphic display of said airport comprising symbols ?presenting said ground traffic, each of said symbols ?ving direction and velocity data displayed;
said processing means comprises means for predicting an ?currence of an airport incursion in accordance with the ?ta received from said sensing means; and means for alerting an airport controller or aircraft ?lot of said predicted airport incursion.

2. The airport incursion avoidance system as recited ? Claim 1 wherein:

each of said light circuits being located along the edges of a taxiway or a runway on said airport.

3. The airport incursion avoidance system as recited in Claim 1 wherein:
said sensing means comprises infrared detectors.

4. The airport incursion avoidance system as recited in Claim 1 wherein said light assembly means comprises:
light means coupled to said lines of said power providing means for lighting said airport;
said sensing means;
microprocessor means coupled to said light means, said sensing means, and said data communication means for providing processing, communication and control for said light assembly means, said microprocessor controlling a plurality of lighting patterns of said light means on said airport; and said data communication means being coupled to said microprocessor means and said lines of said power providing means.

5. The airport incursion avoidance system as recited in Claim 4 wherein:

said light assembly means further comprises a photocell means coupled to said microprocessor means for detecting the light intensity of said light means.

6. The airport incursion avoidance system as recited in Claim 4 wherein:
said light assembly means further comprises a strobe light coupled to said microprocessor means.

7. The airport incursion avoidance system as recited in Claim 1 wherein:
said processing means comprises redundant computers for fault tolerance operation.

8. The airport incursion avoidance system as recited in Claim 1 wherein:
said symbols representing said ground traffic comprise icons having a shape indicating type of aircraft or vehicle.

9. The airport incursion avoidance system as recited in Claim 1 wherein:
said processing means determines a location of said symbols on said graphic display of said airport in accordance with said data receive from said light assembly means.

10. The airport incursion avoidance system as recited in Claim 1 wherein:
said processing means determines a future path of said ground traffic based on a ground clearance command, said future path being shown on said graphic display.

11. The airport incursion avoidance system as recited in Claim 1 wherein:
said processing means for predicting an occurrence of an airport incursion comprises means for comparing position, direction and velocity of said ground traffic to predetermined separation minimums for said airport.

12. The airport incursion avoidance system as recited in Claim 1 wherein said power providing means comprises:
constant current power means for providing a separate line to each of said plurality of light circuits; and network bridge means coupled to said constant current power means for providing a communication channel to said processing means for each line of said constant current power means.

13. The airport incursion avoidance system as recited in Claim 1 wherein:
said alerting means comprises a speech synthesis umit connected to a speaker.

14. The airport incursion avoidance system as recited in Claim 1 wherein:
said alerting means comprises a speech synthesis unit connected to a radio transmitter.

15. An airport incursion avoidance system comprising:
a plurality of light circuits on an airport, each of said light circuits comprises a plurality of light assembly means;
constant current power means for providing a separate line to each of said plurality of light circuits;
network bridge means coupled to said constant current power means for providing a communication channel to said processing means for each of said constant current power means;
infrared detector means in each of said light assembly means for sensing ground traffic on said airport;
means for processing ground traffic data received from each of said light assembly means;
means for providing data communication on lines of said power providing means between each of said light assembly means and said processing means;
said processing means comprises means for providing a graphic display of said airport comprising symbols representing said ground traffic located in accordance with said ground traffic data received from said light assembly means, each of said symbols having direction and velocity data displayed;
said processing means comprises means for predicting an occurrence of an airport incursion in accordance with said ground traffic data received from said sensing means including comparing position, direction aand velocity of said ground traffic data to predetermined separation minimums for said airport; and means for alerting an airport controller or aircraft pilot of said predicted airport incursion.

16. The airport incursion avoidance system as recited in Claim 15 wherein:
each of said light circuits being located along the edges of a taxiway or a runway on said airport.

17. The airport incursion avoidance system as recited in Claim 15 wherein said light assembly means comprises:
light means coupled to said lines of said power providing means for lighting said airport;
said infrared detector sensing means;
microprocessor means coupled to said light means, said sensing means, and said data communication means for providing processing, communication and control for said light assembly means, said microprocessor controlling a plurality of lighting patterns of said light means on said airport; and said data communication means being coupled to said microprocessor means and said lines of said constant current power providing means.

18. The airport incursion avoidance system as recited in Claim 17 wherein:
said light assembly means further comprises a photocell means coupled to said microprocessor means for detecting the light intensity of said light means.

19. The airport incursion avoidance system as recited in Claim 17 wherein:
said light assembly means further comprises a strobe light coupled to said microprocessor means.

20. The airport incursion avoidance system as recited in Claim 15 wherein:
said processing means comprises redundant computers for fault tolerance operation.

21. The airport incursion avoidance system as recited in Claim 15 wherein:
said symbols representing said ground traffic comprise icons having a shape indicating type of aircraft or vehicle.

22. The airport incursion avoidance system as recited in Claim 15 wherein:
said processing means determines a future path of said ground traffic based on a ground clearance command, said future path being shown on said graphic display.

23. The airport incursion avoidance system as recited in Claim 15 wherein:
said alerting means comprises a speech synthesis umit connected to a speaker.

24. The airport incursion avoidance system as recited in Claim 15 wherein:
said alerting means comprises a speech synthesis unit connected to a radio transmitter.

25. A method of providing an airport incursion avoidance system comprising the steps of:
providing a plurality of light circuits on said airport, each of said light circuits comprises a plurality of light assembly means;
providing power to each of said plurality of light circuits;
sensing ground traffic on said airport with means in each of said light assembly means;

processing data received from each of said light assembly means in computer means;
providing a graphic display of said airport comprising symbols representing said ground traffic, each of said symbols having direction and velocity data displayed;
providing data communication between said computer means and each of said light assembly means;
predicting an occurrence of an airport incursion in accordance with the data received from said sensing means;
and alerting an airport controller or aircraft pilot of said predicted airport incursion.

26. The method as recited in Claim 25 wherein said step of sensing said ground traffic on said airport comprises the steps of:
lighting said airport with a light means coupled to said microprocessor means and said power lines;
providing a sensing means;
performing processing, communication and control within said light assembly means with a microprocessor means coupled to said light means, said sensing means and data communication means; and coupling said data communication means between said microprocessor means and said power lines.

27. The method recited in Claim 25 wherein said step of processing data comprises the step of operating redundant computers for fault tolerance.

28. The method as recited in Claim 25 wherein said step of providing power comprises the steps of:
providing a separate line to each of said plurality of light circuits with a constant current power means; and providing a communication channel to said computer means for each line of said constant current power means using a network bridge means.

29. The method as recited in Claim 25 wherein said step of providing a graphic display comprising symbols representing said ground traffic comprises the step of indicating a type of aircraft or vehicle with icons of various shapes.

30. The method as recited in Claim 25 wherein said step of processing said data from each of said light assembly means comprises the step of determining a location of said symbols on said graphic display of said airport in accordance with said data.

31. The method as recited in Claim 25 wherein said step of predicting an occurrence of an airport incursion comprises the step of determining a future path of said ground traffic in accordance with a ground clearance command and showing said future path on said graphic display.