procedural aspects and problems special military...

Day Two June 5 - 9, 2000 117Technical Session Nº2

DAY TWO

PROCEDURAL ASPECTSAND PROBLEMS

SPECIAL MILITARY CONSIDERATIONS

NEW TECHNICAL DEVELOPMENTS.FLIGHT INSPECTION SYSTEMS

STATIC FLIGHT INSPECTION DISPLAY

WEDNESDAY - JUNE 7, 2000


Lieutenant Colonel Dieter KrachBundeswehr Air Traffic Services Office; Section I3Technical Planning of ATC Systems & FlightInspectionP.O. Box 93 02 0860457 FrankfurtGermany

FLIGHT INSPECTION OPPORTUNITIES IN A MILITARY MARKETPotential for Improved/New Flight Inspection Methods

ABSTRACT

The flight inspection procedures for militarycommunication, navigation and surveillance- (CNS)systems differ from country to country. In somestates, soldiers inspect their own military systemswith military aircraft. In other states, military systemsare inspected by the same civil service providersresponsible for the civil systems and some stateshave a combination of both. In Germany, the militaryCNS systems of the Bundeswehr are inspected byFlight Inspection International (FII), a civil serviceprovider. The work of FII is supported byBundeswehr personnel. The purpose of thefollowing paper is to show the challenges andeconomic possibilities provided by the militarymarket.

The paper starts with a brief description of thoseCNS systems of the Bundeswehr that are specificto the military and those that are identical to civilsystems. This is followed by a presentation aboutthe number of CNS systems that need to beinspected, the periodic flight inspection intervals andthe number of flight inspections performed as wellas the costs incurred by these inspections. Ourcurrent flight inspection procedures and possibilitiesfor their optimization are then discussed on the basisof the flight inspection of precision approach radarunits (PAR). This is followed by an overview ofNATO’s Precision Approach and Landing System(PALS). Selected technical data about the CNSsystems used by the military is provided in theannex.

BACKGROUND

The military situation shall be presented on the basisof the military CNS systems in the Federal Republicof Germany. Admittedly, it is difficult to draw generalconclusions about the military field because ofdifferent national regulations, but some universallyvalid statements about military flight inspection cancertainly be made on the basis of the situation inGermany.

On principle, flight inspection is not only necessaryfor civil CNS systems but also for military ones(ICAO Annex 10). While the flight inspection of civilATC systems focuses primarily on ILS and VOR/DME, a multitude of systems ranging from outdatedanalogue to state-of-the art digital technology is stillin existence in military aviation. Normally, thesesystems must be inspected at specified intervals(depending on the type of equipment, these intervalsrange from 3 to 9 months in Germany). At present,the Bundeswehr is in a period of transition. In themedium term, at least part of the military ATCequipment will probably be replaced. Military ATCServices in Germany are currently performed withthe following CNS systems, which have been inservice for up to 30 years.

CNS SYSTEMS SPECIFIC TO MILITARY

Aerodrome Surveillance Radar (ASR)

Primary radar (ASR-910 by Raytheon; in service


since 1979) serves to cover the area of responsibilityof local military air traffic control (≤ 60 NM aroundmilitary aerodromes). The 28 facilities in Germanyare not interconnected but stand-alone units. In themedium term, the ASR-910 will be replaced by newand interconnected equipment. The technical dataof the ASR-910 are provided in the annex.

Secondary Surveillance Radar (SSR)/Identification Friend or Foe (IFF)

The SSR/IFF by Siemens (1990-D1) was developedin the 1970s. It contains digitalized circuits and isinstalled together with the primary ASR 910 (SSR/IFF antenna mounted on top of the primary antennaand SSR/IFF rack inside ASR shelter). The militaryside plans to replace the SSR ground interrogatorsby Mode-S ground interrogators with IFF capability.See annex for technical data.

TACtical Air Navigation (TACAN)

The navigation information provided by TACANcorresponds to that of the VOR with DME. Asopposed to the VOR/DME, TACAN also transmitsthe directional information in the DME frequencyband. The bearing information is determined in theaircraft by a phase comparison. In the Bundeswehr,TACAN facilities are used for en-route navigationand for non-precision approaches (NPAs). Today’sTACAN facilities were installed in the Bundeswehrfrom 1991 to 94. See annex for technical data.

Precision Approach Radar (PAR)

By means of PAR, the approach controller can assistthe pilot during final approach (20 NM or 10 NMfrom touchdown). Deviations of aircraft from theglide path and the centre line are displayed to theapproach controller, who can then pass theinformation on to the pilot by means of UHF/VHFradiotelephony. The PAR systems in Germany willprobably be used until 2010. See annex for technicaldata.

At present, PAR is still the standard system forprecision approaches in NATO member states. The

installation of microwave landing systems (MLS) inItaly’s TORNADO wings is currently in progress. TheUK plans the replacement of ILS/PAR by MLS andILS.

IDENTICAL CIVIL/MILITARY CNS SYSTEMS

Instrument Landing System (ILS)

At seven military aerodromes, the Bundeswehroperates ILS facilities identical to civil systems. Thereplacement of the SEL 3000 facilities, which havebeen in service now for more than 20 years, isimminent. See annex for technical data.

UHF Direction Finder

In the Bundeswehr, the UHF direction finder is usedabove all by approach and aerodrome control unitsfor supporting the rapid identification of aircraft.During ASR flight inspections, the UHF directionfinders are also checked. At present, plans for thereplacement of these systems, which are more than30 years old, do not exist.

Non-Directional Beacon (NDB)

In the Bundeswehr, NDB facilities identical to thecivil systems are used above all for the transporthelicopters of the Army and the Navy. TheBundeswehr plans to utilize the available NDBsystems until 2013.

VOLUME OF FLIGHT INSPECTION

Number of ATC facilities to be inspected

83 military CNS systems are to be inspected atregular intervals. The total number of all the militaryCNS systems of the German armed forces thatrequire flight inspection is 123.

Facility NumberASR/SSR 28TACAN (stationary) 19


TACAN (mobile) 4PAR-80 28ILS 7UHF DF 19NDB 17

Flight inspection intervals

What follows is an overview of the flight inspectionintervals currently in force. For practical purposes,these intervals must not be exceeded by more than25%. If the intervals have been exceeded by morethan 25%, the approach minima are to be changedto those of the approach procedure giving the nextlowest minima (e.g. from precision approach toNPA).

Annex Flight inspection intervalASR/SSR 9 monthsTACAN 9 monthsPAR-80 4 monthsILS 3 monthsUHF DF on requestNDB on request

Flight inspections

For the flight inspection of German military CNSsystems in 1999, approximately 170 inspections and900 flying hours were required.

These figures comprise initial, special and routineinspections by calibration aircraft with activecalibration equipment (ILS, TACAN and NDB, ifrequired) and calibration aircraft without specialcalibration equipment (target representation forASR, PAR and UHF-DF, if required).

In 1999, the cost incurred by the flight inspection ofmilitary CNS systems in Germany wasapproximately DM 6 million (including cost for theBundeswehr’s own flight inspection personnel).

SPECIAL MILITARY CONSIDERATIONS

Today’s flight inspections of PAR 80 systems

To ensure the Cat-I capability of Germany’s militaryaerodromes, 28 Precision-Approach-Radar-80systems (PAR 80) are used in addition to 7 ILSfacilities. A flight inspection of these PAR-80 systemsis currently performed every 4 months. Deviationsof ±0.2 degrees from the nominal value (azimuthand elevation) are admissible.

To check the accuracy of the runway centreline andglide path representation, calibration aircraft(Learjets) are used for target display. The calibrationaircraft is vectored by a military approach controllerand kept in the graticule of a theodolite by anobserver on the runway (near touchdown). Thenominal value (including tolerances) and the flightpath tracked by the theodolite observer arerepresented on a paper strip. According to theinformation provided by the military approachcontroller, the theodolite observer marks on thepaper strip the distance from touchdown and thepoints at which the calibration aircraft is exactly onthe extended runway centreline and/or the glide pathof the PAR-80 indicator. The flight inspection issupervised and controlled by an external militaryflight inspection officer in the approach control room.

This type of flight inspection requires good weatherconditions (necessary oblique visibility ≥ 5NM) andconsiderable manpower (costly). Besides, itdepends on the persons performing the inspection(human factor).

It is conceivable that1. the pilot’s corrections are inadequate, resulting

in insufficient on-glide-path, on-centrelineinformation,

2. the approach controller may not be able tovector the calibration aircraft exactly in themiddle of the cursor,

3. the on-glide-path, on-centreline markings aremade too late/early by the theodolite observer,

4. the calibration aircraft is not kept exactly in thegraticule by the theodolite observer.


In the final analysis, the results of today’s flightinspections do not only depend on the technicalcondition of the PAR-80 but also on the ability ofthe persons performing the inspection (approachcontroller, theodolite observer, pilot and flightinspection officer).

POTENTIAL FOR IMPROVED / NEWFLIGHT INSPECTION METHODS

LASER tracker

As opposed to the theodolite, the laser tracker canbe installed beside the runway. By using an aircraftwith a flight inspection system and a laser trackeron the ground, the runway would no longer beblocked during the inspection (off-set capability) andweather minima could be lower (necessary opticaloblique visibility ≥ 3 NM)

Trials have shown that the more significantadvantage (calibration flights in poorer weatherconditions) is not really decisive as pilots needorientation with ground features (buildings/landmarks) in order to stay on the final approachpath to an acceptable degree of accuracy.

PAR-80 flight inspection in the future?(Direct link between computers)

The military precision approach radar used inGermany has been modified several times in thecourse of the years. The original Gilfillan AN/FPN-33 was upgraded to the AN/FPN-36 and, ultimately,to today’s PAR 80. In the process, some of theelectronic circuits of the PAR-80 were digitalized.Supplying the analogue display units with spareparts is becoming increasingly difficult, which is whythe radar display shall be represented on a computermonitor. The required interface between the radarunit and the computer monitor could also be usedfor flight inspection purposes (analogue-to-digitalconversion of signals).

By means of today’s flight inspection systems usingDGPS technology, the position of a calibration

aircraft can be represented to an accuracy of onedecimeter. It is therefore conceivable that thedigitalized target signal of the calibration aircraftobtained via an interface from the PAR is fed into acomputer where it can be compared directly withthe position that is being down linked by thecalibration aircraft. From our current perspective,this would provide the following advantages:1. The performance of flight inspections would be

largely independent of weather conditions. Theonly minima that would be significant wouldbe those of the aerodrome approach minima.

2. The result of the flight inspection would nolonger depend on the persons performing theinspection.

3. The procurement of suitable recording deviceswould make the result of the flight inspectiontransparent to everybody.

THE PRECISION APPROACH ANDLANDING SYSTEM (PALS) OF NATO

NATO transport, liaison and combat aircraft mustbe able to land under Cat-I conditions at all NATOairbases within NATO territory. NATO’s Approachand Landing Systems Working Group (ALS WG)has been tasked to draw up a StandardizationAgreement (STANAG) for the Precision Approachand Landing System (PALS).

Since NATO member states have not been able toagree on a uniform system for final approach controlat military aerodromes and the new system shouldalso have growth potential for DGPS, differentground components may be introduced by theindividual states. The Precision Approach andLanding System (PALS) comprises:1. an Instrument Landing System (ILS)2. a Microwave Landing System (MLS) and3. a GNSS-based Landing System (GLS)Consequently, the equipment to be installed in NATOaircraft must be capable of interacting with all threesystems (multi-mode receiver) to enable precisionapproaches to aerodromes equipped with one ofthe above ground components.


Once the STANAGs 4533 and 4565 has come intoforce, the individual states will plan the re-equipmentof their military aircraft in accordance with theirfinancial resources and the age and the plannedremaining useful life of the aircraft.

CONCLUSIONS

Until the complete replacement of today’s generationof old military technical ATS facilities, which areequipped for the most part with analogue circuitry,continuing the flight inspection of military facilitiesat regular intervals will be indispensable, at leastduring peacetime operations.

Due to the large number of military technical ATSfacilities and today’s relatively short inspectionintervals, improved and/or new flight inspectionmethods will also be interesting from an economicperspective.

REFERENCES

1.- ICAO Annex 10, «AeronauticalTelecommunications Vol I Radio Navigation Aids»2.- NATO Standardisation Agreement (STANAG) No.3374 «FLIGHT INSPECTION OF THE NATO RADIO/RADAR NAVIGATION AND APPROACH AIDS -AetP-1(B)»3.- NATO Standardisation Agreement (STANAG) No.4533 «PRECISION APPROACH AND LANDINGSYSTEM (PALS) STRATEGY»4.- NATO Standardisation Agreement (STANAG) No.4565 « PALS AIRBORNE MULTI MODE RECEIVER»

ANNEX

Selected technical data:

ASRAerodrome Surveillance Radar (ASR-910)Detection and display of aircraftTX-frequency 2,7 - 2,9 GHzTX-peak power > 500 kWTX-average power > 525 WRange 60 NMAntenna speed 13,5 ± 1,5 UpmRX-sensitivity > - 110 dBmRange resolution > 500 ftAngle resolution > 1,55°Manufacturer Raytheon

Company, Boston,MS, USA

SSRSecondary Surveillance Radar (SSR)/ IdentificationFriend or Foe (IFF)SSR/IFF-Interrogator 1990 D1 / D9Identification of aircraft and height informationTX-frequency 1030 MHzTX-peak power 70/400/800/1600 WRX-frequency 1090 MHzRX-sensitivity > - 84 dBmRange 120 NMManufacturer Siemens, Germany

TACAN (fixed)TACtical Air Navigation (TACAN FTA-43)Bearing and distance informationTX-frequency 962 - 1024 MHz

1051 - 1213 MHzTX-peak power 3 kWRX-frequency 1025 - 1150 MHzRX-sensitivity > - 92 dBmRange: 200 NMBearing accuracy ± 1,5° until 130 NM

± 2,5° beyond 130 NMRange accuracy ± 0,12 NM + 0,05%

of distance until 65 NM± 0,17 NM + 0,05%


of distance beyond 65NM

Manufacturer Standard Elektrik LorenzAG, Germany

TACAN (mobil)TACtical Air Navigation (TACAN AN/TRN-26)Bearing and distance informationTX-frequency 962 - 1024 MHz

1051 - 1213 MHzTX-peak power 400 WRX-frequency 1025 - 1150 MHzRX-sensitivity - 90 dBmRange > 35 NMManufacturer Montek, LTV, USA

PARPrecision Approach Radar (PAR-80)Guidance of aircraft for final approachTX-frequency 9,0 - 9,2 GHzTX-peak power 150 - 180 kWRX-sensitivity > - 100 dBmRange 10/20 NMAzimuth scan - 15,5° - + 15,5 °Elevation scan - 1,7° - + 6,7°Manufacturer ITT-Gilfillan, Los Angeles,

CA, USA

ABBREVIATION LIST

ASR Aerodrome Surveillance RadarATC Air Traffic ControlATS Air Traffic ServiceCNS Communication, Navigation and

SurveillanceDGPS Differential Global Positioning SystemFII Flight Inspection InternationalGLS GNSS-based Landing SystemGPS Global Positioning SystemIFF Identification Friend or FoeILS Instrument Landing SystemMLS Microwave Landing SystemsNATO North Atlantic Treaty OrganizationNDB Non-Directional BeaconNPA non-precision approachPALS Precision Approach and Landing SystemPALS Precision Approach and Landing System

(NATO)PAR Precision Approach RadarSSR Secondary Surveillance RadarSTANAG Standardization Agreement (NATO)TACAN TACtical Air NavigationUHF DF UHF Direction Finder


BASTE FrançoisSAGEM (SFIM industries)180 rue de Paris91344 - MASSY CEDEX / France

ABSTRACT

For several years, the main objective in flightinspection was to improve the implementation,availability and accuracy of the trajectographysystem. SFIM industries solved this problem withthe CARNAC 21(*) flight inspection system morethan 4 years ago and, as a result, ASECNA hasasked SFIM industries to develop a new functionalfeature to improve the partnership in flight inspectionwith airport maintenance teams: The real time «on-board to ground» curves transmission.

Real-time transmission to ground of all acquired andcalculated curves and parameters will enable thenavigation aid maintenance to monitor allmeasurement operations carried out by the flightinspection system.

This function does not only considerably improvethe dialogue between the airport maintenance andthe flight inspectors, it also reduces the time requiredby the maintenance team for beacon tuning.

REAL TIME«ON-BOARD TO GROUND» CURVES TRANSMISSION

Furthermore, the ground engineer permanentlyreceives information on the aircraft position, avionicsinstruments, and various representations of therunway during flight inspection depending on thebeacon to check and the selected sub-function.

Lastly, continuous and real-time complete displayof curves and parameters does not call for any actionby the maintenance team and, consequently, notraining is required.

This paper describes the objectives, the concept,and the technical characteristics of this newfunctional feature.

(*)«CARNAC» is an acronym for: Calibration desAides Radio à la Navigation, à l’Atterrissage et auxCommunications. (Calibration of Radio Aids forNavigation, Landing and Communications).

Figure 1: LOCALISER


During the flight inspection of ILS and VOR radionavigation aids, some inspections run with beacontuning require continuous dialogue between theground maintenance team and the flight inspector.As this dialogue between the on-board and theground team is limited to a simple conversation witha VHF transmitter, it becomes more and morenecessary to improve this aspect of flight inspectionboth in terms of quality and quantity to answer themost important leitmotiv of the 21 century: save timewhile increasing the quality of the service.

The « on-board to ground curves transmission »function is dedicated to these objectives.

CARNAC 21 growth capability allows all theacquired on-board data to be continuouslytransmitted in real time during the flight inspection,without affecting any of the current performancesof the system (fully automatic FIS, very precise D-GPS trajectography up to Cat III, results and reportsimmediately available...).

• First of all, data are acquired by the acquisitionunit (FDAU) which has already been used forcommercial flights by more than one hundredairlines.

• A UHF data link transmits these data to theground station.

• The ground computer which uses the samealgorithms as the on board flight inspectionsystem then processes these data in order toplot the same curves appearing on the plane’sscreen onto the ground display in real time.

Figure 2: Concept - real time«on-board to ground» curves transmission

• Furthermore, the flight inspector continuouslycontrols the ground computer so that he candefine and control all the parameters whichcharacterise the curves (type, scale, ...). Thisadditional possibility allows the flight inspectorto optimise the quality of the information inaccordance with the needs and the technicalenvironment of the mission.

• Of course, the aircraft trajectography information(instruments, mapping...) is also available ona second window, should the ground engineerwish to consult it.

• Therefore, this new equipment enables theground engineer to check the effects of thetuning carried out on the beacon, tocontinuously know the aircraft’s position andto considerably improve dialogue with theflight inspector.

Lastly, the set up is so easy (antenna connection,power on, only one function key needed to togglebetween Mapping display and curves) that themaintenance team needs no special training.

During the mission’s set-up phase, the flightinspector selects all the parameters which are usedby the « on-board to ground curves transmission »function. This configuration is defined by selectingin scroll boxes. Of course, all the parameters canbe modified quickly during the flight inspection.

The system is installed in the ground shelter of thebeacon to be calibrated by simply connecting thepower supply and the UHF antenna.

Figure 3: General block diagram


The ground engineer starts up the equipment byusing the power on switch, and then uses only asimple key to toggle between the real time curvesplotting and the aircraft path.As the data transmission is in real time, the beacontuning modify instantaneously the curves and theparameters selected by the flight inspector anddisplayed on the ground system.

Thanks to a permanent access possibility to theconfiguration menu of the « on-board to groundcurves transmission » function, the flight inspectorcan modify the parameters and the curves whichare displayed on the ground system in accordanceto the needs of the mission.

The ground engineer who tunes the beacon hasone window which shows:

Either real time curves plotting of the tunedparameters

Or aircraft moving on a map with instruments

This equipment runs automatically, because it iscontrolled by the aircraft flight inspection system.The ground engineer need only select the window:either the one with the curves or the one with themapping and instruments.

Figure 4: Ground operator display


This equipment is used during ILS and VOR flightinspections when ground beacon tuning isnecessary.

After the power has been switched on, the systemstarts automatically at the beginning of the mission.For each new run, the curve plotting starts and stopsautomatically.

In the aircraft, the flight inspector can, at any time,consult his display to see the curves beingtransmitted to the ground system and modify theparameters and scales in real time.

TECHNICAL CHARACTERISTICS

The aircraft flight inspection system sends data tothe ground equipment with a data link.

Figure 5: Ground container

The ground equipment is fitted into a suitablecontainer including:

• A portable computer with an LCD display• A 9600 baud data-link receiver• A UHF antenna.

General specifications

Power requirements: 110/220 V AC 80 W

• Dimensions (Width, height, depth):470 x 260 x 320 mm185'' x 102'' x 126''

• Weight:Container : 10 Kg (22 lbs)Antenna with tripod: 8 Kg (18 lbs)

Environmental characteristics

• Temperature: 0°C/+ 40°C operating(- 20°C/ + 70°C storage)

• Altitude: 20 000 ft operating(40 000 ft storage)

• Humidity: 95 % RH at 40°C

Performances

• VOR / ILS software with two windows:- Curves and parameters- Map with instruments

• 1 Hz data update• Range up to 8 Nm.


Martyn WillsTechnical ManagerFlight Precision LimitedTeesside AirportDarlington DL2 1NJEngland

FLIGHT INSPECTION DATA DOWNLINK.11th IFIS

ABSTRACT

The engineering and commissioning of radionavigational aids such as ILS is a team effortbetween the flight inspector and the groundequipment engineer, a task complicated by thephysical separation of the two participants.

The Flight Inspector has all of the performance dataof the aid available to him in real time; he mustthen communicate this to the ground engineer toenable adjustments to be made to optimise thesystem.

Sponsored by a major customer, FPL has workedwith Aerodata to develop a system to present flightinspection data directly to the ground equipmentengineer in near real time. This allows the groundengineer to see the results of his adjustmentsimmediately, improving both the effectiveness of theengineer, and the quality of the navigation aid. Inaddition, this system helps minimise the flightinspection flying, and consequent delays toscheduled air traffic.

This paper details the development of that system,looks at applications, benefits and possible futureenhancements.

BACKGROUND

Discussions with customers led FPL to investigate thepossibility of providing flight inspection data to ILS

ground engineers in near real time. It was intendedto demonstrate the system at the 11th IFIS, but forcommercial rather than technical reasons, the projecthas been delayed.

CONCEPT

The flight inspector has a multitude of informationavailable to him during the course of the flightinspection. To enable the engineers on the groundto adjust the system for optimum performance, theflight inspector must relay this data. In the case ofabsolute figures i.e. sdm and RF coverage, then RTcommunication is sufficient. For optimisation ofaerial phasing or path structure, it is difficult tocommunicate an onscreen graphic verbally over anRT link. For this reason, FPL proposed to send dataover a telemetry link in near real time, such that theground engineer could observe the graphical plots,enabling him to make adjustments and see the effectsimmediately.

TECHNICAL DESCRIPTION

Initial system design is for ILS data, but the designallows for future expansion to incorporate otherradio navigation aids.

Data from the f l ight inspection system isencoded, and transmitted by a simplex UHFtelemetry link.


The ground system consists of a radio-modem,and a laptop PC.

Diagram 1

Overview of the Data Downlink System showingmajor components.

The design considerations made included thefollowing main points:

• The system should be fully portable, and requireno input except power.

• The ground PC should operate a standardMicrosoft Windows operating system.

• The ground system should require little trainingin operation.

• The ground system should require no user actionafter initialisation, but be capable ofcustomisation.

• All hardware should be ‘off the shelf’.

* Hard copies of the screen should be available.

• There should be a facility to save data to diskfor later analysis.

To achieve the above criteria, the following solutionwas researched. The telemetry link is unidirectionalusing UHF radio modems. This does not allow theuse of handshaking but CRC protection is used toflag ‘bad’ data. The data rate is 4800 baud. Thisallows the transmission of 9 parameters at 2Hz,and 2 parameters at 5Hz, which, together with thecontrol data occupy 75% of the availablebandwidth, allowing inclusion of additionalparameters as required.

A header block is transmitted at regular intervalsinterlaced with the data blocks, and is used toconfigure the ground system without operatorintervention.

The ground system acts as a dumb terminal. This ishosted on a laptop PC running MS Windows NT4or 98. Once the program is initialised, it waits toreceive data from the flight inspection aircraft. Oncedata is received, the first header block to be decodedwill set the configuration of the ground system, toinclude software version number, Facility ID, Profile,Time and default graphic display. Data is onlytransmitted during the manoeuvre, and for a shortperiod after, this is automatically detected by theground system.


Diagram 2Data Downlink PC Display

For ILS, the following parameters are transmittedduring manoeuvre:

• Aircraft Range• Aircraft Height• Aircraft Bearing• Localiser Deviation• Localiser RSL• Localiser sdm• Glidepath Deviation• Glidepath RSL• Glidepath sdm

These are transmitted at a rate of 2Hz, additionallythe following parameters are transmitted at a rateof 5Hz;

• Localiser Error (structure)• Glidepath error (structure)

All parameters are displayed in an Alphanumericwindow, with any two parameters being selectablefor display as graphics.At the end of an approach manoeuvre, therecalculated ILS structure is transmitted at anequivalent data rate of 10Hz, together with ICAOtolerance lines.

All of this data is stored to the PC hard disk for lateranalysis. The data will remain on screen until sucha time as the flight inspector initiates anothermanoeuvre.

With this information on the PC screen, the groundsystems engineer is able to see the results ofadjustments immediately, and so better optimise thefacility.

The ground engineer can obtain a hard copyprintout of the screen to any suitable printer, thusenabling him/her to keep a record of theinformation presented for later use or comparison.


The system has thus met the design criteria from thecustomer’s point of view. An additional facilitydesigned from inception is the ability to add amodem and GSM telephone to the ground system.This gives the ability to display the information inreal time on a suitably equipped PC and Modemanywhere in the world. This opens up many excitingpossibilities.

Diagram 3Forwarding of downlink data to remote PC

Future enhancements being considered are:

Addition of MLS functionality.Addition of VOR/DME functionality.Additional parameters.Data Compression.Storage of user defined graphics.

CONCLUSIONS

FPL believes that this is a way forward, utilisingtechnology that is now available to us in order tobenefit both the customer and the end user. Thecustomer benefits by having the necessaryinformation available to him to set up the facility

for optimum performance, and the end user benefitsby receiving a better navigation service.

ACKNOWLEDGEMENTS

System development and graphics courtesy of:

AerodataFLUGMESSTECHNIK GmbHHerman-Blenk-Strasse 36D-38018 Braunschweig.Germany.

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