AWE: Aviation Weather Data Visualization Envir onment

Lilly Spirkovska�

NASA AmesResearchCenterSureshK. Lodha

�

Univ. of California,SantaCruz

Abstract

The two official sourcesfor aviation weatherreportsbothprovideweatherinformation to a pilot in a textual format. A numberofsystemshaverecentlybecomeavailableto helppilotswith thevisu-alizationtaskby providing muchof thedatagraphically. However,two types of aviation weatherdataare still not being presentedgraphically. Theseare airport-specificcurrent weatherreports(known asmeteorologicalobservations,or METARs) andforecastweatherreports(known asterminalareaforecasts,or TAFs). Oursystem,Aviation WeatherEnvironment(AWE), presentsintuitivegraphicaldisplaysfor both METARs andTAFs, aswell aswindsaloft forecasts.Westartwith acomputer-generatedtextualaviationweatherbriefing. We map this briefing onto a cartographicgridspecificto the pilot’s areaof interest. The pilot is able to obtainaviation-specificweatherfor theentireareaor for hisspecificroute.Theroute,altitude,trueairspeed,andproposeddeparturetime caneachbe modified in AWE. Integral visual display of thesethreeelementsof weatherreportsmakesAWE a usefulplanningtool, aswell asaweatherbriefingtool.

1 Intr oduction

Weatheris one of the major causesof aviation accidentseventhoughpilots are requiredto receive an official weatherbriefingprior to flight. Theseofficial weatherbriefingsaretextualor verbaland the pilot is responsiblefor mentallyvisualizing the providedinformation. Pilots often turn to unofficial sourcesfor weather,suchastelevision news weatherreports,the WeatherChannel[3],or a variety of weatherweb sites[12,7, 16, 11, 17], becausetheyoffer a graphicalpresentationof much of the sameinformation.Thesegraphicalweatherdisplaysallow the pilot to quickly builda bettermentalmodelof thebig pictureof theweather. However,the unofficial sourcesoften provide only a generalview of whatthe weatherwill be like. The informationprovided (for example,40% chanceof rain) is suitablefor non-specializedtasks(suchasattendingaparade)butnotfor tasksthatrequireadeeperknowledgeof conditions(for example,answeringthequestionWill thecloudsbelow enoughto requireflight underinstrumentflight rules,or canI fly undervisualflight rules?).

Aviation specificweatherdatais too detailedfor generalpublicinformationsources.But becausethis graphicalbriefinghasbeenfoundto besohelpful,moreaviation specificweatherinformationsourceshave recentlybeenintroduced[4, 12]. They graphicallypresentmuchof the dataavailablein the official aviation weatherbriefing. Two piecesof the weatherbriefing which are not wellpresentedgraphicallyare currentweatherreportsat selectedair-ports of interestand the forecastweatherfor a subsetof thoseairports. Thesepiecesarepresentedeitheronly textually or usingvery simplecolor-codedsymbolswhich presentnothingmorethanwhetherthe conditionsimply visual flight rules, marginal visualflight rules, or instrumentflight rules. AWE fills this gap byproviding veryeasyto understandgraphicsfor bothairport-specific

�E-mail: spirkov@wolfie.arc.nasa.gov�E-mail: lodha@cse.ucsc.edu

currentweatherobservations and forecasts. This information isvery importantfor selectinga route,selectinga destinationairport,planningfor alternatedestinations,andselectinganalternateroutein caseof equipmentfailure. We also integratevisualizationofwindsaloft informationto helpthepilot selecttheoptimalaltitudeaswell asa goodroute. Winds aloft arealreadydisplayedusingthewell-known directionalarrow with barbsrepresentingthewindspeed. We presenta simpler representationthat is quickly andeasilyinterpreted.

In the next section,we discussprevious work on visualizingofficial aviationweatherandsomerelatedwork onaviationspecificvisualizations.We thendescribein moredetailourofficial weatherdatasourceavailablevia computer, known asDUATs, anddiscusshow AWE helpspilots visualizecurrentandforecastweathercon-ditions extractedfrom DUATs. We concludewith evaluationsbypilots,pointingoutAWE’sadvantagesandcurrentlimitations.

2 Previous Work

Official weatherbriefingscan be obtainedvia telephone,aircraftradio,or infrequently, in personfrom aFlight ServiceStation(FSS)specialist1[8, 9], or via computerfrom the DUATs (Direct UserAccessTerminal) system.[4]Face-to-facebriefingswith an FSSspecialisthave theadvantageof accessto graphicaldisplaysof thedata. This advantageis outweighedby the limited availability ofFSSfacilities.

DUATs recentlyintroducedweathergraphicsto help pilots vi-sualize the ”big picture.” They provide charts similar to thoseavailablethroughFSS,includingsurfaceanalysisandsurfacefore-castchartsthatshow thecurrentandforecastlocationof high/lowpressuresystemsandwarm/coldfronts, andareasof precipitationor low-visibility conditions; infrared satellite charts; and chartsdepictinginstrumentflight rules(IFR2) conditions,marginalvisualflight rules (MVFR3) conditions, or visual flight rules (VFR4)conditions. An examplechart is shown in Figure1. The chartsarevery effective in providing a broad(nation-wide)overview ofthe weather, but they do not provide information about specificlocations,suchas airportsalong the pilot’s route. In particular,DUATs doesnot provide graphicalencodingsof threeof themostimportantelementsof a weatherbriefing: airport-specificcurrentweatherobservations(meteorologicalobservations,or METARs),terminalareaforecasts(TAFs),andwindsaloft forecasts.

AnotherrecentlyintroducedWorld Wide Web site for aviationspecific weathergraphicsis provided by the National WeatherService(NWS)[12]. Unlike the DUATs site, the NWS site isexperimentalandunofficial. However, it providesa greatervarietyof graphics,and allows pilots to zoom in to get more specificinformationaboutan areaof interest. In additionto the standardchartsprovided by DUATs, NWS provideschartsthat graphicallyencodeMETARs and TAFs. The encodingis very simplified,

1FSSspecialistsareFederalAviationAdministration(FAA) employees.2IFR = visibility � 3 milesand/orceiling � 1000feet.3MVFR = (3 miles � visibility ��� 5 miles)and/or(1000feet � ceiling

��� 3000feet).4VFR = visibility � 5 milesandceiling � 3000feet.

Figure1: An exampleof graphicsavailablethroughDUATs. Thissurfaceanalysischartshowslow pressuresystems(”L”), coldfronts(the blue line acrosssouthernCalifornia) and warm fronts (thered line from Colorado,throughKansasandOklahoma),areasofprecipitation(suchastherain in NorthernCaliforniaandthunder-stormsin easternKansasandeasternOklahoma).

Figure 2: A METAR display available through the NationalWeatherServicewebsite. Eachcircle representsaMETAR report.Thecolor-codingprovidessomeinformationoncurrentconditions,suchas visual flight rules in effect (greencircles) or instrumentflight rules in effect (red circle). A circle must be selectedwiththemouseto extractmoreinformation.

however, anddoesnot provide muchinformationbeyondwhetherthe weatheris IFR, MVFR, or VFR. Figure 2 shows a METARdisplayprovidedby theNWS site. To get informationbeyond thecolorcodes,theusermustselectthecirclefor theairportof interest.Theobservationdatais thendisplayedtextually in thevicinity of theairport, similar to the TAF displayin Figure4. Their handlingofTAFsis alsoelementary. As Figure3 shows,theNWSTAF displayshows only which airportshave terminalforecastsavailable. Theuserneedsto selectindividual TAF squaresto get the associateddata.As shown in Figure4, thedataavailablefor thatairportis thenpresentedwithout any filtering basedon departuretime or anotherselectedtime.

Thoughelementary, theDUATs andtheNWS graphicssystems(as well as the many othersimilar but non-aviation weatherwebsites [3, 7, 16]) are useful as a supplementto official pre-flightbriefings. They provide well-designedgraphicsfor much of theavailabledata.However, neithersitefully utilizesthepilot’s visualpatternmatchingskills but still reliesa greatdealon his cognitiveskills in interpreting METARs and TAFs. We focus on whatthey neglect. AWE presentsan intuitive, graphicalpresentationof theseelementsand provides an environment that allows thepilot to quickly determinecurrentandforecastconditionsalonghisplannedroute,determinealternateroutesor alternatedestinations,andeven explore his optionswith quick ”what-if” scenarios.The

Figure3: A TAF displayavailable throughthe NationalWeatherServicewebsite.Eachairportthathasa terminalforecastavailableis representedby asquare.

Figure4: TheTAF squarescanbeselectedwith themouseto obtainthe full text associatedwith a NWS TAF display. The TAF is notspecificto the pilot’s time of arrival at that airport. Rather, all ofthe informationavailableis shown. Theappropriateforecastmustbeextractedanddecipheredby thepilot.

easyinteractionimprovesthe pilot’s understandingof currentandforecastconditionsduringthepre-flightbriefing.

3 Related Work

BeforedescribingAWE andits datasource,wediscusstwo relatedapplicationsof visualizationin the aviation area. First, we beginwith the exploratory work of Pruyn and Greenberg[10]. One ofthe moredifficult proceduresis flying an instrumentapproachinIFR conditions. The pilot must refer to a specialapproachchartdetailinghis desiredheadingandaltitudeat differentpositionsinthe airspacesurroundingthe airport. Simultaneously, he mustflythe airplane,settingpower andpitch appropriatelyfor the desiredeffect. Pruyn and Greenberg appliedvisualizationtechniquestohelpthepilot moreeasilyvisualizetheapproach.Pilotsfoundfly-ing simulatedapproacheswith theseenhancedgraphicsto beeasierthanusingonly thestandardapproachchart.Thoughtheiremphasisis not on visualizingweatherdata,they do considershowing thepilot asimulatedwind sock(showing thewind directionandspeed,similarto thewind sockat theairport)to givehim extrapreparationtimefor whenhebreaksout of thecloudsandis readyto land.

Anotherapplicationof visualizationtechniquesin aviation is thework by Azuma and his colleagues[1]. One of the latestdevel-opmentsfundedby the FAA is for alternative control strategiesof aircraft operatingunderinstrumentflight rules(suchasairlineflights). This programis known as Free Flight and will allowpilots to determinetheir routeof flight with minimal coordinationwith FAA air traffic controllers. Eachpilot will bearmoreof the

responsibilityfor conflictresolutionwith otherflights,leavingFAAair traffic controllerswith moreopportunityto dostrategic planningrather than just immediatecontrol. Azuma’s researchfocuseson providing pilots graphicaldisplaysthat show them whetheranearbyflight’s pathwill converge with their own andon makingpossibleconflictsvisually obvious. FreeFlight is independentofweather, but they do sharean enablingtechnologyknown asdatalink. We discussdatalink in moredetailbelow. First we describeAWE andits datasource.

4 Data Source: DUATs

AWE beginswith anofficial weatherbriefingasavailablefrom theDUATs computersystem. DUATs, Direct User AccessTerminalsystem,is offeredby privatecompaniesundercontractto theFAA.It is availableto all pilots, from studentpilot onward. We usedtheGTE DUAT system. It obtainsits datafrom the FAA, which inturnobtainssomeof its datafrom theNationalWeatherService.ADUATsareabriefingprovides:

� AreaForecastincludingpositionof fronts,pressuresystems,wind conditions,cloudlayers,weather(suchasrain), andanoutlook statingwhetherconditionswill be IFR, MVFR, andVFR.

� SevereWeatherWarnings

� SIGMETs5 andConvectiveSIGMETs6

� AIRMETs7 for turbulence,mountainobscuration,widespreadIFR conditions,andicing conditionsandfreezinglevels.

� SurfaceObservations(METARs8) of currentconditions,in-cluding ceilings, visibility, wind, barometricpressure,tem-peratureanddew pointsfor certainairports.

� Pilot Reports

� RadarSummariesthat textually provide information aboutechos,echomovement,andechointensity.

� TerminalForecasts(TAFs9), includingceiling, visibility, andwind forecastsfor certainairports.

� Winds Aloft Forecastsfor relevant sitesat altitudesof 3000feetto 39000feet,by 3000foot increments.

� NOTAMs, or Noticesto Airmen, which provide informationon suchthingsasairportclosures,unlightedobstructions,outof serviceequipmentsuchasrunway lights,etc.

As we mentionedpreviously, DUATS graphics,NWS graph-ics, andweathergraphicsavailableto the generalpublic, suchasthoseshown on television newscastsor the WeatherChannel,doa reasonablejob of displayingmuchof the informationpilots finduseful. Specifically, low/high pressuresystems,cold/warmfronts,sequencesof satellite imagesshowing clouds and cloud move-ment,andsequencesof radarimagesshowing areasof precipitationare displayedin an easyto understandformat. Someof thesesourcesalsoprovide graphicsfor forecastsfor wide-spreadareasof thunderstorms,high wind speeds,or fog. Thus, visualizationof mostof thetextual DUATs briefingis alreadyavailable. Ratherthanduplicatingthis work, we focuson two elementsthatarenot

5SignificantMeteorologicalConditions6Example:thunderstorms7Airman’s MeteorologicalInformation8METAR is anacronym for MeteorologicalObservation.9TAF is anacronym for TerminalAreaForecast.

availablegraphically:thelatestweatherreportsfor selectedairports(METARs) andthe forecastreportsfor theseairports(TAFs). Al-thoughNWS displayswinds aloft reportsin an easyto interpretmanner, we explore a simplerdisplayapproachbut provide addi-tional functionality to help the pilot plan his flight. An exampleof eachof theseelements(slightly modified for easeof parsing)is shown in Figure 5, Figure 6, and Figure 7. The integratedvisualdisplayof thesethreeelementsallowsapilot to morequicklyrecognizeand understandthe currentand forecastweatherin anareaof interestandquickly determinehis routeof flight includingaltitude.

Windsaloft: Thewindsaloft reportbeginswith theairportiden-tifier (i.e. KSFO)andthengivesthedirectionthewind is comingfrom (in tensof degrees),the wind speed,andthe temperatureateachof theprespecifiedaltitudes.As anexample,theKSFO(SanFrancisco,CA) airport winds aloft report ”KSFO 1112 1010020908-04...” statesthat the wind at 3000 feet (the first elementfollowing the airport identifier) is comingfrom 110 degreesat 12knots,andthe temperatureis not specified.Similarly, thewind at6000feet(thesecondelement)is from 100degreesat 10knotsandthetemperatureis 2 degreesCelsius.

METAR:TheMETAR reportalsobeginswith theairportidenti-fier. Wewill deciphertheKSQL (SanCarlos,CA) airportMETARasanexample:”KSQL 181646Z18014KT8SMFEW012SCT050BKN080 11/08 A3022.” ”181646Z” specifiesthe time of obser-vation in the format of day and UTC time, popularly referredtoas Zulu time. Thus, ”181646Z” representsan observation timeof 16:46 Zulu on the 18th of the month. ”18014KT” gives thesurfacewinds at the airport andspecifiesthat the wind is comingfrom 180 degreesat 14 knots. Note that unlike the winds aloftreport,thewind directionis specifiedhereasa threedigit number.The visibility is ”8SM” (statutemiles). Thereareno restrictionsto visibility. Comparethis with the METAR for ”KSAC” (shownin Figure6) where”FG,” or fog, is restrictingvisibility. Thecloudlayersarespecifiednext. SanCarloshasa few cloudsat 1200feet,scatteredcloudsat 5000feet,andbrokencloudsat 8000feet. Thetemperatureis 11 degreesCelsiusandthe dew point is 8 degrees.Finally, thebarometricpressureis 30.22inHg (inchesof Mercury).

TAF: Interpreting the TAF report is similar to the METARreport. As an example, we will translatepart of the KSJC(SanJose,CA) airport TAF: ”KSJC 181730Z18181800003KTP6SMSCT200BECMG 222332017KTP6SMFEW050SCT200FM090018020KT3SMBR BKN020OVC080” Thereporttime ison the 18th of the monthat 17:30Zulu. The forecastis valid forthe 18th from 18:00Zto the 19th at 18:00Z.The weatherwill be3 knot winds from 0 degrees,visibility 6 statutemiles or greater,with scatteredcloudsat 20000feet. Between22:00Zand23:00Zit will become(”BECMG”) wind from 320 degreesat 17 knots,plus 6 sm visibility, with a few cloudsat 5000feet andscatteredcloudsat 20000feet. Finally, from 09:00Z (the following day),the wind will be from 180 degreesat 20 knots, the visibility willbe 3 statutemiles with mist (”BR”), with broken cloudsat 2000feetandovercastcloudsat 8000feet. Note that theFAA providesa standardinterpretationof the cloud cover amount:FEW means1/8 of the sky or lessis obscuredby clouds,SCT meansbetween1/8 and3/8 of the sky hasclouds,BKN means4/8 to 7/8 of thesky, andOVC meanstheentire(8/8)sky hasclouds.TheFAA alsoprovidesa list of standardcontractionsfor visibility obscurations.Our examplesarenot for comprehensive coverage,but ratherforgeneralunderstanding.Hence,only a few optionsarediscussed.

5 AWE Appr oach

The Aviation WeatherEnvironment,AWE, provides an environ-ment for the pilot to interactwith and obtain the informationheneedsto effectively plan a flight. AWE is written using C++,

OpenGL,andXformsandrunsonanSGIworkstation.For in-flightuse(asdiscussedlater), it waseasilyportedto a Sony SuperslimProNotebook

computerrunningMandrake Linux. Theinput to the

AWEprototypeisaDUATsbriefingfor aspecificarea,for example,a 95 nauticalmile (nm) radiusfrom the Palo Alto airport,KPAO.We mapthis briefingontoa grid specificto thepilot’s routeor hisareaof interestandonly includeinformationrelevant to his flight.For instance,for route-specificweather, ratherthandisplayingcur-rentdataavailablefor hisdestination,weuseforecastsavailableforhisproposedtimeof arrival (automaticallycomputedfrom hisrouteandchosendeparturetime). Weusevisualizationtechniques[2, 14,15] suchascolorcodediconsto presenttheinformationin themostcognitively easyto decipherformat.

Much underlyingcapability is requiredto visualizea DUATsbriefing. This includesproviding AWE information about air-ports10, parsingthe briefing, and translatingit into a computer-understandableversion.Theuser’s interactionwith AWE requiresa differentsetof capabilities.AWE allows the userto specifyhisflight includingroute,desiredaltitude,trueairspeed,andproposeddeparturetime; selectwhetherhe wantsto seecurrentweatherorforecastweather;and selectwhetherthe areaof interestis justairportsalongtherouteor all airportsin thearea.Theuseris abletomodify any of therouteparametersandseetheeffectonweatherhemight encounter. We discusseachof theseissuesin the followingsections.

5.1 AWE Foundation

Theunderlyingcapability, or AWE’sfoundation,consistsof object-orientedprogrammingclassesthat deal with information aboutairports,METAR, TAF, andwindsaloft. It alsoincludessupportingclassesthat know how to dealwith latitudeandlongitudecoordi-natesandcanfind distancesbetweenlat/long locations.Four datafiles are usedby AWE. Airport identifiersas well as the latitudeand longitude coordinatesof the airport are specifiedin a userreadabledatafile, andthe DUATs briefing is translatedinto threeseparatefiles: one containingcurrent METARs, one containingTAF forecasts,andonecontainingwindsaloft forecasts.

The winds aloft forecastis transferreddirectly with little mod-ification. The classthat dealswith winds aloft containsmethodsfor retrieving the obvious elements. We also provide a methodfor forecastingthe winds aloft at an arbitrary lat/long location.DUATs only provides winds aloft for certain locationsand forcertainaltitudes. Thuswe mustdo two interpolationsto computethe appropriatewind. We begin by determiningthe winds aloftfor the pilot specifiedaltitudeat the two closestreportingstationsusinglinear interpolationof thealtitudesspecifiedby DUATs. Wethen usedistance-basedinterpolation,with a slight modification,to determinethewindsat thespecifiedlatitude/longitudelocation.Becausethe windsaloft for a locationneara reportingstationarelikely to be affectedmuchmoreby conditionsat that stationthana moredistantone, if the arbitrary location is within 30 nm of astation,our forecastis basedentirely on the local stationwinds.Figure5 showsasamplewindsaloft file.11

Sinceour emphasisis on exploring how bestto representinfor-mationandhow to bestallow the userto interactwith a weatherenvironmentsystem,ratherthanrigorouslyparsingDUATs output,the METARs and TAFs are modified from their original format,as shown in Figure 6 and Figure 7. For instance,we alwaysassociatean obstructionto visibility. If none was given in theDUATs briefing,we insert”NO.” Also, we deletetheinput format

10Locationsof navigation aids, like VORs (VHF OmniRange),wouldalsobeusefulandcaneasilybeaddedto AWE.

11For easeof parsing,whenwe translatewinds aloft reportsfor usebyAWE, we arbitrarilychoose0 degreesfor thefirst temperature.

Figure5: Samplewindsaloft file. Theairportidentifieris followedby groupsof three elements: wind direction, wind speed,andtemperature.Thesegroupsof threeareavailablefor prespecifiedaltitudesfrom 3000feetto 39000feet,in 3000foot increments.

Figure6: SampleMETAR file. Eachline representsa METAR fora specificairport,specifiedby theairport identifier (first element).It alsospecifiesthe time of observation, wind directionandwindspeed,visibility, visibility restrictions,cloudlayers(with coverageamountandaltitude),temperature,dew point,andbarometricpres-sure.

commentsandextra notationsassociatedwith METARs andinsertsemi-colonsinto TAFssowecansimplify our parser.

The two final foundationclassesare Awe interfaceand Awe.Awe interfacedealswith interactionswith the user, properlyup-datingthe input forms. The Awe classmaintainsa list of knownairports, and readsand updateswinds aloft, METAR, and TAFreports. It alsoprovidesvarioussearchmethods,suchasfindingtheclosestairportto anarbitrarylatitude/longitudeposition;gettingtheMETAR/TAF for anairportwith reportingcapability;gettingarepresentative METAR/TAF for non-reportingairports;finding theclosestandsecondclosestwinds aloft forecasts;or keepingtrackof theuser’s chosenroute.Eachof thesemethodsis usedby otherfoundationclassesto helpprovidewhattheuserwants.

5.2 Graphical Interface and Displa y

The graphicsportion of AWE relieson the foundationclassestocomputewhatinformationto display. Wewill now discusshowwedisplay it. We begin by texturing the backgroundAWE windowwith our local areaof the SanFranciscoSectionalAeronauticalchart. The chart shows the location of airports,navigation aids,controlledand specialuse airspace,obstructions,natural terrainfeatures(suchas water and hills, depictedusing color codedal-titudes),andcongestedareas(suchascities, depictedin yellow).Althoughit maylook clutteredandcomplex, thechartbackgroundtexture givespilots a familiar environmentwith which to interactand provides them with additional information for making their”go/no-go” decision. For example,a 2000foot ceiling presentsadifferentsituationif the airport is in a flat region versusa narrowvalley surroundedby tall mountains. Overlaying the weatheronthe chartconsolidatesthe weatherandthe terrainsurroundingtheairportallowing thepilot to makeadecisionby lookingonly atonesource.

Figure 7: SampleTAF file. A TAF for an airport extendsfromthe airport identifier to the dot (”.”). EachTAF providesthe timethe forecastwas createdfollowed by the effective times of eachforecastelement. Eachelementspecifiesthe wind direction andspeed,visibility andrestrictionsto visibility, andcloudlayers(withcoverageamountandaltitude).

Defining the Flight

Thepilot specifieshis routeof flight by selecting(with themouse)a sequenceof airports.12 The useris able to extendhis routebyaddinganairport to theend,modify his routeby deletingairportsoff the end until the modification point is reached(eventuallybacktrackingto the beginning if desired),or specifya new route.As airportsareaddedor deleted,the interfaceis updatedto reflectthe currentspecifiedroute. The backgroundscreenwith a routeselectedby thepilot areshown in Figure8.

Usingsliders,thepilot is ableto selecthisflight altitudeandtheaircraft’s trueairspeed.Thepilot is alsogivenaninput window inwhich to specifyhis proposeddeparturetime. Theseselectionsareusedto determinewhatspecificinformationto display, asdiscussedbelow.

Selecting Information Overla ys

AWE providesthepilot with anumberof optionsin selectingwhatinformationto overlay. Theseinclude:

� Display focus: displayareawide weathervs. routespecificweather;

� Type of weather: display current weather observations(METAR) or forecastweather(TAF), and/orwindsaloft;

� Displayformats:displayasymbolicrepresentation,aniconicrepresentation,or a textual representationof eitherMETARsor TAFs.

� Reportlocality: displayonly weatherfor airportswith report-ing capability or also display closestavailable weatherforairportswithout reportingcapability.

Wedescribeeachof theseoptionsbelow.Display Focus: The pilot can chooseto display weatherat

airportseither just alonghis routeof flight, asshown in Figure8

12As statedearlier, AWE doesnot currently recognizenavigation aidssuchasVORs.

or at airports in the entire area known by AWE, as shown inFigure9. Theareawide weatheroptionis especiallyusefulduringthe planningphase.The pilot canview all availableweatherandthenchoosea routeof flight. Conversely, if hehasalreadychosena destination,routespecificweathershows him only informationrelevantto hisflight.

Type of Weather: The pilot can chooseto view either current(METAR) or forecast(TAF) weather, aswell aswindsaloft infor-mation. Most (probablyall) airports that provide TAF forecastsalso provide METAR observations. Therefore,we implementedtheoptionsto displayMETARs or to displayTAFs to bemutuallyexclusive to avoid screenclutter; that is, eitherMETARs or TAFscanbedisplayed,but not bothsimultaneously. Windsaloft, on theotherhand,providecomplementaryinformationto bothsourcesandcanbedisplayedeitheraloneor with a TAF or METAR. METARsandTAFs provide surfacewindsassociatedwith the reportingair-port. Windsaloft reportsprovidewindsat variousaltitudesandareassociatedwith amuchwiderareaaroundtheairport.

DisplayFormats:AWE providesthepilot with threeoptionsonhow to display the METAR and TAF reports: symbolic, iconic,and textual. The symbolicand iconic representationsshow onlypartof the information,but show it graphicallymakinginterpreta-tion quicker. The textual representationshows all the informationprovided by DUATs, eliminating only commentsassociatedwithMETARs as mentionedpreviously. All three optionsprovide adifferentperspective andareusefulin differentsituations.Detailsof therepresentationsarepresentedbelow.

Reportlocality: Not all airportsAWE knowsabouthaveweatherreportingcapabilities.If thepilot is viewing routespecificweather,we provide him with theoptionof choosingto displaythenearestreport(METAR or TAF) for airportsthatfit thiscriteria.To accom-plish this, the pilot choosesthe ”show closestavailableweather”option.

Time-dependentInformation:Pilotsneedtheforecastweatheratthe time of arrival at eachen-routecheckpoint(airport, in AWE),not the forecastfor the departuretime. To eliminatethe needforthe pilot to specify a full flight plan with expectedarrival times,we calculatearrival times automaticallybasedon the specifiedtrue airspeedanddeparturetime. If the pilot is looking at route-specificTAFs, he will be given the appropriateforecastbasedonthis information.

ChoosinganAppropriateForecast:Determiningtheappropriateforecastis not assimplefor a computerasit is for a person.DU-ATs forecastsarenot specifiedasmutuallyexclusive time ranges.Rather, asillustratedin Figure7, the generalforecast(given first)covers a 24 hour period. Forecastsfor more specific times arethengiven. Even thesespecifictime periodscanoverlap. As inthe KSCK (Stocktonairport) TAF of Figure7, we seethat threeforecastsapplyfor 10:30.First,thegeneralonethatspanstherange18:00 on the 18th of the month to 18:00 on the 19th statesthattheweatherwill be wind 300@6,visibility 6 statutemile (sm)orbetter, sky clear� . Then,the”FM1000”, statesthatfrom 10:00,theweatherwill be wind calm,visibility of 1 smwith mist,sky clear� .Finally, the ”TEMPO 1015” statesthat therewill be a temporaryconditionfrom 10:00to 15:00of weather visibility 1/4 sm withfog, anda vertical visibility of 200 feet� . AWE must determinewhich oneof theseto presentto theuser. AWE choosesto presentthe worst scenario. Thus, in this case,it choosesthe temporaryconditionastherepresentativeweather.

Displa ying Information Overla ys

Wenow turn to thedisplayformats.Winds Aloft Display: Displayingwind information is straight-

forward. We rotatethe wind arrow to show the direction of thewind at that locationanddisplaythe wind speedalongside.This

Figure8: RouteMETARs andwindsaloft shown alongsidea pilot-selectedroute.A pink arrow graphicallydepictsthewind direction.Thenumberalongsidethearrow representsthewind speed.Therouteis specifiedby clicking ontheairportsymbolsandis shown by thedarkblueline. TheMETARsareshown in symbolicform (theverticalrectangle)andtextual form. Thetextual form providesall theelementsavailablein the DUATs METAR. The symbolic form shows the more importantinformationgraphically, employing the pilot’s patternrecognitionabilitiesmorethanhiscognitive abilities.Thetop portionshows thewind directionandspeed(thedirectionis shown by thedirectionof thearrow, while thespeedis shown by thethicknessof thearrow). Thebottomportionis subdividedinto thecloudlayers.Thecloudcoverageamountis color-codedwith lighter colorsequatingwith lesscoverage.Thus,clearsky conditionsareshown aswhite,whereasovercastskyconditionsareshown asvery darkgray. Thelighter colorsposeno problemsevento VFR only pilots. Thedarker colorsmaysignaladverseconditionsthatneedto beexaminedfurther.

is simplerthantheFSSandNWS methodof displayingwindsbyattachingbarbsto the rotatedwind arrow. Eachbarb representseither5 knotsor 10 knots,dependingon its length. Our methodemphasizesthe wind directionover the wind speed.We alsofindit’ s easierto quickly reada number(the wind speed)ratherthancountbarbsandtry to determinewhetherit’ s ashortbarbor a longone.

If the pilot hasrequestedareawide weather, AWE displaysallknown winds aloft forecastsfor central California. If the pilotrequestsrouteweather, ontheotherhand,wedisplaywind informa-tionalongsideeachairportalonghisroute,interpolatedasdescribedaboveandillustratedin Figure8by thepinkarrows. In thiscase,thewindsaloft aregiven only for KSFO(theselectedrouteairport inthemiddleleft sideof thechart)andKSAC (theselectedrouteair-port at thetop of thechart).Thewindsdisplayedfor theothertwoairports(KMOD (middleright sideof chart)andKSNS(bottomofchart))arecomputedby AWE. Displayingwindsaloft graphicallyallows the userto quickly comparehis flight path to the path ofthe wind and determinewhetherto expect a tailwind, headwind,or crosswind. It helpshis situationalawarenessby giving him adirectpictureof expectedconditions.He canthencompensatefora crosswindwithout muchthought,or expectto go slower andusemorefuel for a strongheadwind.Becausewindsaloft arealtitudedependent,the pilot canmodify his selectedaltitudeto determinewherethewindsaremostfavorable.Thedisplayis updatedin realtime to reflecthisselection.

SymbolicMETAR/TAF Display: Determininghow to displayaMETAR or aTAF to make it easilydecipherableyetprovideall thenecessaryinformation is more complicated. The FAA approach,usedwith chartsavailableat Flight ServiceStations,arevery in-formative, yet very cryptic. Their symbols,shown in Figure10,requirealot of memorizationandcanbeeasilyforgottenif notusedregularly. Instead,we couldchooseto follow theWeatherChannelapproachanddisplayonly a small setof symbols.Onedisadvan-tageof this approachis that muchof the available informationisnot represented.

Figure10: FAA weathersymbolsandtheir associatedmeanings.Thesesymbolsareusedon chartsavailableat Flight ServiceSta-tions,andmorerecentlyon DUATs andNWS chartsavailableontheweb.

We choseto provide thepilot with all the informationavailablebut also to give him the option to only view part of it. As men-tionedpreviously, thepilot hastheoptionto askfor all information

Figure 11: Close-up view of a symbolic representationof aMETAR. Thebluerectangleatthetoprepresentsthewind directionandspeed.Thedirectionis shown by thedirectionof thearrow. Inthis casethe wind is comingfrom theSouth. The speedis shownby thethicknessof thearrow’s base.In this case,it’ s fairly windy(in the rangeof 16 knots). The gray part of the rectangleshowsthe cloud layers. Cloud coverageamountsarecolor coded,withlighter colorsrepresentinglesscoverage.Hence,white representsclearconditions,very light gray correspondsto few clouds,lightgray to scatteredclouds,mediumgray to broken clouds,anddarkgrayto overcastcloudcoverage.Thegrayrectangleshows theskyconditionsfrom 0 to 12,000feet. Thecloudaltitudeis representedby thefractionof therectanglecoloredby theassociatedgraycolor.In this case,we seefew or no cloudsup to about6000 feet, ascatteredlayer from 6000 feet, and a broken layer above 8000feet. The upperaltitudeof the cloud coverageis not provided byMETARsandthuscannotbeshown. Thecloudrectangleborderisblack in this casesignifying VFR conditions.It would becoloredyellow for MVFR and red for IFR conditions. Text below thesymbolprovidesvisibility andany restrictionsto visibility (nonein thiscase).

textually attachednext to the airport, askfor only an iconic viewthat provideshim with a ”feel” for the weather, but no specifics,or askfor a symbolicview which provideshim with an overviewof the weatherin a very easyto interpret format. The standarddisplay usesthe symbolic representationas shown in Figure 8.Figure11 shows a close-upview of thesymbolfor KSQL airport.Each symbol is packed with information. The box at the topdisplaysthe surfacewinds. An obvious glyph to usefor aviationapplicationsthat allows the coding of both wind direction andwind speedis a wind sock. Every airport hasoneandpilots areable to interpretthem readily. The direction is displayedby theorientationof the wind sock and the speedis displayedby theamountthe wind sockis straightenedto the 90 degreeorientation(with respectto the pole holding it up). We attemptedto useawind sockto displaywind informationassuggestedby PruynandGreenberg[10] but found the 3D wind sock did not merge wellwith the overheadperspective of our 2D view. Also, one of theadvantagesof displayingthe wind direction is diminishedwhenusingthewind sock:whenusinga wind arrow, thepilot caneasilycomparethewind directionwith theorientationof therunwaysasdisplayedonthesectionalchart(AWE’sbackgroundimage).Thus,crosswindlanding conditionsbecomevisually obvious. The 3Dwind sock requiresmore analysisto extract similar information.Therefore,our surfacewinds display follows a similar model towinds aloft with one modification. Winds aloft all usethe samesize arrow; the wind speedis presentedtextually adjacentto thearrow. In contrast,thewidth of thesurfacewind arrow varieswiththespeedof thewind. Light winds (that is, low wind speeds)arerepresentedby thin arrows, whereasstrongwinds arerepresentedby thick arrows. Comparethewindsat KSNS(22 knots)shown inFigure13andKMOD (3 knots)shown in Figure14.Also noticethewindsat KLVK shown in Figure15.Thewind vectorat KLVK is 0degreesat0 knots,or calm.Calmwindsarerepresentedwith justa

Figure12: Close-upview of a textual representationof a METAR.Thewind directionis shown by thearrow. Thewind directionandwind speedare alsoshown by the text in the upperright corner.In this case,the wind is comingfrom 60 degreesat 3 knots. Thevisibility is 5 mileswith ’BR’ or mist. Cloudlayersaregivenasafew cloudsat 1500feetandscatteredcloudsat 5000feet. Finallythetemperature/ dew point areboth4 degreesandthebarometricpressureis 30.21inHg. Thecoloredrectangle(yellow) representsmarginalVFR (MVFR) conditions.It wouldbecoloredredfor IFRconditionsor grayfor VFR conditions.

dotsincenodirectionis associatedwith them.Finally, theborderofthewind squareis colorcoded.A redbordersignifiesstrongwinds( �� 20 knots),an orange/yellow bordersignifiesmediumwinds( �� 15knots),andno bordersignifieswindsbelow 15knots.

Figure13: Close-upview of theKSNSMETAR symbol.

Figure14: Close-upview of theKMOD METAR symbol.

Thenext elementof theMETAR/TAF symbolis a rectanglethatpresentsthecloudlayers.Therectanglerepresentsthesky from 0 to12,000feet.13 Wethenpseudo-colortherectangleto show thecloudlayers[6, 13]. As suggestedby Bertin[2] andTufte[14], we chosea gray scaleto representthe cloud amountsso pilots do not needto rememberacolor key. Darker colorsrepresentthicker coverage.Hence,whiterepresentsaclearsky. Verylight grayrepresentsafewclouds,adarker light grayrepresentsscatteredclouds,mediumgrayrepresentsbrokenclouds,andfinally, verydark(nearlyblack)grayrepresentsanovercastsky. Ceilings(definedasbrokenor overcastlayers)are thusquickly recognizedby scanningfor darker grays.The borderof the rectangleis alsocolor codedto instantlyshowwhetherthe cloud andvisibility conditionsare IFR (red border),MVFR (orange/yellow border),or VFR (black/noborder).

The final elementof a METAR/TAF symbol is text specifyingthe visibility and obstructionsto visibility. That information ispresentedin black and blendsin morewith the backgroundthan

13We chose12,000feetbecauseautomatedweatherobservationsystems(AWOS)usethesameheightthresholdfor reportingclouds.

Figure15: Close-upview of theKLVK METAR symbol.

therestof thesymbol. In this way, the informationis thereif it isneeded,but it is notoverwhelming.

The METAR/TAF symbolsdo not representthe temperature,dew point,or barometricpressurevalues.Also, thevaluesfor cloudaltitudesare shown only indirectly (by the amountof rectanglefilled). If any of thosevaluesare desired,the symbol can betransformedinto a text box containingall availableinformationasdiscussedin thenext section.

Textual METAR/TAF Display: A textual display of METARinformationis shown in Figure12. To makethetaskof recognizingcrosswindconditionsquicker, we still representthewind directiongraphicallyaswell astextually. Unlikethesymbolicrepresentation,however, we useonly a single width arrow and alsoprovide thedetailstextually.

Thetextual displaysaresupplementedwith color-codedbordersto warn the pilot of possibleadverseconditions. Recall that IFR,InstrumentFlight Rules,apply whenthe visibility is �� 3 milesor theceiling14 is �� 1000feet. Many pilots arepreventedeitherlegally (by not having appropriatecertification)or practically(bynot beingproficient)from landingat airportswith IFR conditions.MVFR conditionsareonly a practical,not a legal,deterrent(manypilots feel lesssafein marginalconditions).AWE displaysairportswith IFR conditionswith a redborder, airportswith MVFR condi-tionswith a yellow border, andthosewith VFR conditionswithoutaborder.

Iconic METAR/TAF Display: Therearefour primary elementsthataffectapilot’s”go/no-go”decision:wind conditions,visibility,cloudaltitude,andtemperature/ dew point spread.Thefirst threeelementsareencodedby our METAR/TAF symbols. The last oftheseelements(temperature/dew point spread)is only availableinMETARs. Although our METAR symboldoesnot encodethem,temperatureanddew point canbe importantin certainconditions.For instance,in the SanFranciscobay area,morningandeveningfog is often a consideration.The temperature/ dew point spreadthen becomesvaluable information. If the airport is currentlyexperiencingfog, thespreadgivesinformationonwhenit mayclear(especiallyif you have the previous hour’s METAR and can seea trend in how the spreadis changing). Similarly, in the heatofthesummer, temperatureis very importantat high altitudeairportssinceit hasa directeffect on aircraftflight characteristics.On theotherhand,low temperatureshave aneffect on startingtheengineandthey cancontribute to possibleice on the airframe. Usually,though, temperaturescan be safely classifiedas non-critical in-formationand are not representedin the iconic format; only thetemperature/ dew pointspreadis represented.

Our iconsaredesignedto presenta quick overview of all fourprimaryelements.They alsogive a moreabstractsummaryof theweatherthanprovided by the METAR/TAF symbols. The icon isa triangle(modeledafterwarningtriangles)that is subdivided intofour triangles,eachrepresentingoneof theimportantelements.Thewind triangle (at the top) is shown in white if the wind speedislessthan15 knots(kts), yellow if it’ s between15 kts. and20 kts.,andred if it exceeds20 kts. The visibility triangle(lower left) is

14Ceiling is definedasabroken(BKN) or overcast(OVC) layer.

shown in white if thevisibility is greaterthan5 nm, yellow if it isbetween3 and5 nm,andredif it is lessthanor equalto 3 nm. Thecloud� altitudetriangle(lower right) is shown in white if thelowestceiling layeris greaterthan3000feet,yellow if it’ sabove1000andbelow 3000feet,andred if it’ s at or below 1000feet. Finally, thetemperature/ dew pointspreadtriangle(center)is shown in whiteifthespreadis greaterthan4.5degreesCelsius,yellow if it’ sbetween2 and4.5 degrees,andred if it’ s below 2 degrees.BecauseTAFsdo not provide temperatureor dew point forecasts,the TAF iconconsistsof justthreetriangles.The(center)temperature/ dew pointspreadtriangle is always shown in gray. In eachof thesecases,the color codingservesonly to alert the pilot of possibleadverseconditions.Thethresholdswerechosento coincidewith theFAAdefinitionsof IFR andMVFR conditionsfor visibility andceiling.The wind speedsandtemperaturedew point spreadswerechosenbasedonatypicalpilot andweatherprofile. An examplearea-wideTAF displayusingiconsis shown in Figure16.

6 Benefits of AWE

AWE wasevaluatedby one instrument-ratedpilot andtwo VFR-only pilots, in additionto oneof theauthors,who is aninstrument-ratedcommercialpilot. All the pilots found AWE to be a veryusefultool for examiningweatherconditions.

AWE’sbenefitsrevolvearoundproviding only relevantinforma-tion in aneasyto interpretformatthatsupplementsthepilot’s cog-nitive abilitieswith his patternmatchingcapabilities.With AWE’ssymbolic format, detectingareasof good weatherconditionsisreducedto lookingfor regionsof whiteor light graycloudbarsandgrayborders.Similarly, regionsof adverseconditionsaredetectedby looking for darker gray cloud bars or red, yellow, or coralborders.Theiconicformatprovidesaquicksummaryof thecurrentor expectedconditions. In a glance,pilots can quickly deducewhethertheremaybepotentiallyadverseconditions.Finally, usingthe textual display option, a pilot can drill down and get all theavailabledetails.

Oneof theotherusefulaspectsof AWE is its useasa planningtool. Selectinga departuretime that offers the best conditionsyet fits a pilot’s previous commitmentsis greatly simplified byAWE’sautomaticselectionof theappropriateforecastbasedonthedeparturetime. Selectinga routeor determiningpossiblealternateroutesin casesof incorrectforecastsare alsosimplified with theinteractivity provided by the true airspeedand altitude sliders.He can decideto climb to a more favorablealtitude, slow downand exploit tailwinds while saving fuel, or departearlier or laterdependingon the forecast.He canexamineall his optionsalmostinstantaneously. If he is flying for pleasure,he caneven chooseto fly southratherthannorth if the weatheris more favorableinthatdirection. Extractingsimilar informationfrom DUATs (eithertextually or graphically)or from theNWS site,thoughpossible,ismuchmoretimeconsuming.

One of the evaluatorspointed out that in addition to AWE’sfeaturessimplifying theformationof a mentalmodelin thepilot’slocal area,they vastly improve his ability to form mentalmodelsin an unfamiliar area. Pilots know the identifiersfor most, if notall, the airportswithin 100 miles of their homeairport. They canimmediatelypicturewherea given airport is, how far away it is,andwheretheirflight pathwill passin relationto it. If aTAF is notavailable for their destinationairport, they know which airport isclosestandwhichmayprovide usefuldataon expectedconditions.Non-local pilots, on the other hand, have a more difficult timeinterpretinga DUATs areabriefing. They must refer to the chartor otherreferencematerialto determinewhich airportanidentifierrefersto, to visualizewhereairportsarelocated,to determinewhichairport is closestto onewithout a TAF, andto visualizewhat theterrainsurroundingthe airport looks like. All that informationis

directly availableon AWE. They cannow visualizetheweatheraseasilyin adistantareaasthey canin their localarea.

A final observation was that AWE is useful not just for pre-flight briefings but also for in-flight weatherupdates. Becauseoneof the leadingcausesfor loss of control for generalaviationflights is continuedflight into worseningweatherconditions,theprudentpilot getsin-flight weatherupdatesto verify his pre-flightbriefing. The only resourcecurrentlyavailablefor in-flight brief-ings is (aviation) radio contactwith FSSspecialistsandhenceallbriefingsareverbal.Becauseof frequency congestionandrequiredflying tasks,thesebriefingstendto bebrief andprovide only veryspecificinformation.Thepilot is unableto contemplatehisoptionsat length.

TheFederalAviationAdministration(FAA), NationalAeronau-tics andSpaceAdministration(NASA), andaviation industryarecurrentlydevelopingdatalink technologywhichpromisesto bringmuchneededdatadirectly to thein-flight pilot.[5] Thedriving goalfor data link is the FreeFlight programthat will allow pilots todeterminetheir routeof flight with minimalcoordinationwith FAAair traffic controllers.Besidestraffic data[1], datalink canbeusedto transferweatherdata to the pilot or sendweatherdata fromon-boardsensorsto a centrallocation for dissemination(as pilotreports)to otherflights in thegeneralarea.Becauseof bandwidthlimitations, datalink proponentsareconsideringproviding muchof the informationin a textual format. However, with the dutiesrequiredby single-pilotoperations,this datamustbe presentedina cognitively easyto decipherformat if it is to provide optimalhelp. AWE canprovide onesolutionto this problemwith a slightexpansionof thefeaturesetandsomeadditionalhardware.

WeportedAWE to amorepracticalplatform- a laptopcomputer- asdiscussedearlier. We areableto accessthe aircraft’s currentpositionby connectingthelaptopto aGPS(globalpositionsystem)unit. AWE can usethis real-timeposition datato automaticallyscroll the areadisplayedon the chart. Data transferfrom/to theground is madepossiblethroughemerging satellitephonetech-nology. QualcommrecentlydemonstrateddatatransferusingtheGlobalstarnetwork of satellites.The technologyis scheduledforreleasebeforeyear’s end. Thus,by connectinga satellitephonetoournotebookcomputer, wecandownloadtheDUATs text while inflight anywheresatellitedatatransfercoverageis available. Usingthis setup,the pilot canautomaticallydownloadweatherupdates(attimespre-programmedduringpre-flightpreparations)andgetanupdateddisplayof weatherconditionsin his en-routeanddestina-tion areas.BecauseAWE graphicsdisplaytheinformationsoonlysimplevisualpatternmatchingis required,weatherupdateswill notrequiremuchhead-down time15 And becausethewholeprocesscanbeautomated,thepilot canalwayshave thelatestavailableweatherandmodify hisplansaccordingly.

7 Future AWE Enhancements

Theevaluator-pilots alsopointedout additionalfeaturesthatcouldimprove AWE. First, we have hardwiredcloudbarsto show cloudlevels only from 0 to 12,000feet. The upperlimit waschosentocoincidewith automatedobservationsystemlimits andtheperfor-mancelimitationsof many generalaviation aircraft. Allowing theuserto specifythisupperboundwouldmakeAWEusefulto alargervariety of pilots. Similarly, the definition of adverseconditionshasbeenhardwired. For example,wind speedsin excessof 20knotsareshown with a redborderin thesymbolicor a redtriangleon the iconic display. Cloud altitudeandcoverageamountcolorcodingscoincide with the FAA definitionsof IFR, MVFR, andVFR. Allowing the userto specify theseboundariescould make

15Head-down time is time spentfocusingon instrumentsor datainsidethecockpitratherthanscanningoutsidefor traffic.

Figure9: AreaMETARs. All theMETAR reportsavailablefor thechartedarea.METARs canbeshown in symbolicor textual format,asshown here.They canalsobeshown in iconic format,asdescribedin thetext. Theinterpretationof thesymbolsis exactlyasin thepreviousfigure.

Figure16: Area TAF displayusingicons. Eachof the TAFs availablefor the chartedareaareshown usingthesetriangularicons. Eachsub-trianglerepresentsa differentelementof the TAF. The top triangleportraysthe wind conditions,the left bottomtriangleportraysthevisibility conditions,andtheright bottomtriangleportraysthecloudlayers.Eachsub-triangleis color codedto signify VFR (white),MVFR(yellow), andIFR (red) conditions. The wind triangleusessimilar colorsbut representslight winds,mediumspeedwinds,andexcessivewinds.

AWE evenmoreusefulfor lessexperiencedpilotsor to pilotswhere20knotwindsareroutine.

The� secondareafor additionalfeaturesinvolvesvisualizingtwoadditionalelementsof DUATs briefingsthat are currently beingdisplayedonly textually: pilot reportsandnoticesto airmen.Pilotreports(PIREPs)provide information similar to METAR obser-vations. Ratherthanbeingcollectedby instrumentsor air trafficcontrollers, in-flight observations are collectedand reportedbypilots. Becauseforecastsare not always accurate,PIREPsareusefulin confirmingtheforecastor pointingoutareaswhereit wasnotaccurate.They areespeciallyhelpful for determiningtheextentof icing conditionsandthetopof thecloudlayers.

Noticesto airmen(NOTAMs) provide a variety of informationpotentially helpful to a pilot. Some NOTAMs, such as thosespecifyinginstrumentapproachprocedurechanges,aretextual bynature. Others,however, provide information which could moreeasilybeinterpretedif presentedvisually. Someexamplesof theseareNOTAMs for unlightedobstructionsneartheairport,acrobaticpracticeareas,active parachutejumpingsites,temporarilyprohib-itedareaswheretheU.S.Presidentis scheduledto be,andareasofpossiblyreducedGPSreception.

8 Summar y

AWE presentsa new methodof interactingwith aviation weather.It can be usedeither as a briefing tool or as a planning tool.We begin with an areabriefing from the FAA-approved DUATsaviation briefingservice.We thenpresenta subsetof theprovidedinformationgraphically. Thesubsetis selectedto augmentcurrenttechniquesfor visualizingweatherinformation.Theuseof satelliteimagesto displayclouds,radarechosto displayprecipitation,andcontour lines to display temperaturesare well known and quiteeffective. The display of winds as arrows is also currentlyusedeffectively. Weconcentrateondisplayingaviationspecificweatherthat is not currently displayedeffectively. In particular, AWEdisplayscurrentairportweatherobservations,known asMETARs,andairportweatherforecasts,known asTAFs.Althoughthedisplayof wind direction and speedhasbeenexploredpreviously, AWEalso displayswinds aloft databecausewe find it integrateswellwith METARsandTAFsandis veryusefulto thepilot for planningpurposes.

AWE provides the pilot optionsto displayarea-wideor route-specificwindsaloft, currentMETAR observations,andTAF fore-casts. METARs and TAFs can be displayedeither as symbols,higher-level icons,or asa text box. Text boxespresentthe sameinformationasDUATs(exceptthatwesimplifiedtheDUATsbrief-ing to accommodateour parsingroutinesby discardingcommentsand extra details). Symbolsand icons presenta quick, easilyinterpretableview of weatherconditionsin general,makingadverseconditionsvisuallyeasyto detect.

AWE providesa simplemethodof specifyinga route.By usingthemouseandits threekeys,thepilot canaddacheckpoint,modifytherouteby deletingcheckpointsoff theend(backto thebeginningif sodesired)andreplacingthemwith othercheckpoints,or specifya new routeby clearingthe previously specifiedrouteandaddingcheckpoints.AWE alsoallows the pilot to specifyhis airplane’strueairspeed,selectanaltitude,andselecthis departuretime. Anyof thesecanbemodifiedduringhisAWE session,turningAWE intoausefulplanningtool. METARs,TAFs,and/orwindsaloft dataareupdatedimmediatelyto reflectthenew selections.Thus,thepilotcanchoosea favorablealtitude(e.g.,with moretailwinds),chooseto slow down andsave fuel if thewindswill let him arrive withina time window of his choice,or chooseto departearlieror later tousetheforecastweatherto hisadvantage.Therecreationalpilot canevenuseAWE to decideon a directionfor his pleasureflight. Thedirect visualizationof weathercanespeciallybenefitpilots flying

outsideof their local areaby helpingthemseewherethe airportsidentifiedin theweatherbriefingarelocatedandhow far they arefrom eachother.

Ratherthanjust displayingweatherinformationdirectly, AWEprovides someautomationof functionstypically performedby apilot. Winds aloft for flight path checkpointsare computedbyinterpolatingthewindsat thetwo nearestreportingstations.Theseestimatesare displayedalongsidethe checkpoints. Conditionsspecifiedby METARs and TAFs are automaticallyclassifiedasIFR, MVFR, or VFR anddisplayedso they areeasyto recognize.Finally, thepilot is giventheoptionof usingthenearestairportwitha METAR or TAF as a representative for oneof his checkpointsif the checkpointairport doesnot provide thoseservices. Thecombinationof thesefeaturesmakes AWE a very useful tool forlocalandnon-localpilotsalike.

9 Ackno wledg ement

The authorsgratefully acknowledge the suggestionsfrom fellowpilotsDavid Iverson,CedricWalker, andButlerHine.

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