AWE: Aviation Weather Data Visualization

Lilly Spirkovska�

NASA AmesResearchCenterSureshK. Lodha

�

Universityof California,SantaCruz

Abstract

The two official sourcesfor aviation weatherreportsboth requirethe pilot to mentallyvisualizethe provided information. In con-trast,our system,Aviation WeatherEnvironment(AWE) presentsaviation specificweatheravailableto pilots in aneasyto visualizeform. We start with a computer-generatedtextual briefing for aspecificarea.Wemapthisbriefingontoagrid specificto thepilot’sroutethatincludesonly informationrelevantto hisflight asdefinedby route,altitude,trueairspeed,andproposeddeparturetime. Bymodifyingvariousparameters,thepilot canuseAWE asaplanningtool aswell asaweatherbriefingtool.

1 Intr oduction

TheNationalWeatherService(NWS)andtheFederalAviationAd-ministration(FAA) gatheranddisseminatea greatdealof weatherinformation helpful to pilots. Weatherobservations both at thesurface and aloft, real-time radar information, satellite observa-tions, radiosondeballoonsand forecastspreparedby meteorolo-gists are packagedand disseminatedto pilots at least once perhour. Pilotshave two primarysourcesfor official weatherreports:Flight ServiceStation(FSS)specialists1 and the DUATs (DirectUserAccessTerminal)2 computersystem.FSSspecialistscanbereachedvia telephone,aircraft radio, or infrequently, in person.In any case,the briefing is verbalandthe pilot is responsibleformentallyvisualizingthe provided information. DUATS computerbriefingsaretextual andalsorequirethepilot to mentallyvisualizethe ”big picture.” Pilots often supplementtheseofficial briefingswith graphicsavailable from the WeatherChannelor unofficialweatherweb sites. Becausethis supplementalinformationis notgearedtowardaviationapplications,however, it is oftendifficult toextractnecessaryinformationeasily.

Weatheris oneof themajorcausesof aviation accidents.Con-tinued flight into worseningconditions(with the optimistic hopefor improvement)is one of the leadingcausesof loss of controlfor generalaviationflights. Improvementsin technology(primarilydata link) promiseto bring much neededinformation directly tothe in-flight pilot [1]. However, data link proponentsare stillconsideringproviding muchof theinformationin a textual format.With thedutiesrequiredby single-pilotoperations,this informationwill needto bepresentedin acognitively easyto decipherformatifit is to provideoptimalhelp.

Oursystem,theAviationWeatherEnvironment,AWE, proposesonesolutionto this problem. In its ultimateconfiguration,it willprovideanintelligentinterfaceto weatherdatafor thein-flight pilot.The pilot will be able to quickly determinecurrentand forecastconditionsalonghis plannedroute,gethelp determiningalternateroutes or alternatedestinations,and get automaticwarningsofworseningconditions.Eitherthepilot or anintelligentagentactingon his behalfcanexplore”what-if” scenariosto determineoptimal

�Email: spirkov@wolfie.arc.nasa.gov�Email: lodha@cse.ucsc.edu

1FSSspecialistsareFAA employees.2DUATsis offeredby privatecompaniesundercontractto theFAA.

plans. Data link technologieswill be exploited to get currentweatherfrom groundfacilitiesaswell asotherairborneaircraft.

Becausethis technologyis still underdevelopment,our initialsystemprovidesthepilot with acognitively easyto decipherformatfor DUATsbriefings.Westartwith aDUATsbriefingfor aspecificarea,for example,a 95 nauticalmile (nm) radiusfrom the PaloAlto airport, KPAO. We map this briefing onto a grid specifictothepilot’s routethatincludesonly informationrelevantto hisflightasdefinedby route,altitude,trueairspeed,andproposeddeparturetime. The pilot is ableto visualizecurrentareaweather, forecastareaweather, or routespecificweather. For routespecificweather,rather than displaying current data available for his destination,we use forecastsavailable for his proposedtime of arrival. Bymodifying variousparameters,the pilot can also useAWE as aplanningtool.

2 Previous Work

Before the consolidationof Flight ServiceStations,pilots wereable to physically visit with an FSSspecialist. Specialistshaveaccessto chartsthat graphicallydisplaycurrentconditionsandalimited set of forecasts[4]. Theseinclude the following charts:surface analysischart, weatherdepiction chart, radar summarychart,significantweatherprognosischart,windsandtemperaturesaloft chart,compositemoisturechart,severeweatheroutlookchart,constantpressureanalysischart,andtropopausedatachart.A greatdealof informationis availableto a pilot [3]; somuchin fact thatmostpilotsdo not know how to readmostof thesecharts,nor howto interpretwhat thedatais telling them. Hencetheneedfor FSSspecialists.

A numberof websiteshaverecentlybeencreatedwhichattemptto provide informationsimilar to that provided by the FSSchartsdescribedabove [6, 2, 5]. They typically displayweatherfor theentire U.S., but do not allow the pilot to zoom into a region ofinterest,suchas alonghis route. Also, as in the FSScharts,theinformation is distributed throughmultiple charts. Integrationoftheinformationis still performedby thepilot.

DUATs compressesmuch of this data and packagesit verydifferently in an attemptto make it easierto understandfor thepilots.However, it isbasedonold teletypetechnologyandis crypticto read.A textualDUATsareabriefingprovides:

� AreaForecastincludingpositionof fronts,pressuresystems,wind conditions,cloudlayers,weather(suchasrain), andanoutlookstatingwhetherconditionswill be IFR, MVFR, andVFR 3.

� SevereWeatherWarnings

� SIGMETs4 andConvective SIGMETs5

3IFR = InstrumentFlight Rules: visibility ��� 3 miles and/orceiling��� 1000feet;MVFR = Marginal VFR: visibility ��� 5 milesandceiling��� 3000feet; andVFR = Visual Flight Rules: visibility � 5 miles andceiling � 3000feet.

4SignificantMeteorologicalConditions5Example:thunderstorms

� AIRMETs6 for turbulence,mountainobscuration,widespreadIFR conditions,andicing conditionsandfreezinglevels.

� SurfaceObservations(METARs7) of currentconditions,in-cluding ceilings, visibility, wind, barometricpressure,tem-peratureanddew pointsfor certainairports.

� Pilot Reports

� RadarSummariesthat textually provide information aboutechos,echomovement,andechointensity.

� TerminalForecasts(TAFs8), includingceiling, visibility, andwind forecastsfor certainairports.

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

3 AWE Appr oach

AWE presentsanew methodof interactingwith aviationweather. Itcanbeusedeitherasabriefingtool or asaplanningtool. Webeginwith anareabriefingfromtheFAA-approvedDUATsaviationbrief-ing service.We thenpresenta subsetof theprovided informationgraphically. The subsetis selectedto augmentcurrenttechniquesfor visualizingvariousinformation. Theuseof satelliteimagestodisplay clouds, radarechosto display precipitation,and contourlines to display temperaturesare well known andquite effective.The displayof winds asarrows is alsocurrentlyusedeffectively.We concentrateon displayingaviation specificweatherthat is notcurrentlydisplayedeffectively. In particular, AWE displayscurrentweatherobservations,known asMETARs, andweatherforecasts,known asTAFs. Althoughthedisplayof wind directionandspeedhasbeenexploredpreviously, AWE alsodisplayswindsaloft databecausewe find it integrateswell with METARs andTAFs andisveryusefulto thepilot for planningpurposes.

AWE provides the pilot optionsto displayarea-wideor route-specificwindsaloft, currentMETAR observations,andTAF fore-casts. AWE usesstandardvisualizationtechniquessuchascolorcoded icons to presentthe information in an easy to decipherdisplayformat.

AWE allowstheuserto specifyhisflight includingroute,desiredaltitude,trueairspeed,andproposeddeparturetime;selectwhetherhe wants to seecurrentweatheror forecastweather;and selectwhethertheareaof interestis just therouteor area-wide.Theuseris ableto modify any of therouteparametersandseetheeffect onweatherhemightencounter.

Additional underlyingcapabilityis requiredto visualizea DU-ATs briefing. This includesproviding AWE information aboutairports9, parsingthe briefing, andtranslatingit into a computer-understandableversion. We discusseachof theseissuesin thefollowing sections.

3.1 AWE Foundation

AWE is written usingC++, OpenGL,andXforms andrunson anSGI workstation.Theunderlyingcapability, or AWE’s foundation,consistsof object-orientedprogrammingclassesthatdealwith in-formationaboutairports,METAR, TAF, andwinds aloft. It alsoincludessupportingclassesthatknow how to dealwith latitudeand

6Airman’s MeteorologicalInformation7METAR is anacronym for MeteorologicalObservation.8TAF is anacronym for TerminalAreaForecast.9Locationsof navigation aids, like VORs (VHF OmniRange),would

alsobeusefulandcaneasilybeaddedto AWE.

longitudecoordinatesandcanfind distancesbetweenlat/longloca-tions. Four datafiles areusedby AWE. Airport identifiersaswellasthelatitudeandlongitudecoordinatesof theairportarespecifiedin a userreadabledatafile, and the DUATs briefing is translatedinto three separatefiles: one containingcurrent METARs, onecontainingTAF forecasts,andonecontainingwindsaloft forecasts.

Thewindsaloft forecastis transferreddirectly with little modi-fication.Theclassthatdealswith windsaloft containsmethodsforretrieving theobviouselements.Wealsoprovideameansof findingthefreezinglevel (definedasthelevel atwhichthetemperatureis 0degreesCelsius).Finally, we provide a methodfor forecastingthewindsaloft at anarbitrarylat/longlocation. DUATs only provideswindsaloft for certainlocationsandfor certainaltitudes. We usedistance-basedinterpolationto determinethewindsat thespecifiedlat/longlocation.

Becauseour emphasisis on visualizationandnot parsing,theMETARs andTAFs aresomewhat simplified. Additional parsingcapability will be neededto deal with more of the informationDUATs provides. The major simplificationwe implementedwasfor cloud layers. DUATs briefings provide multiple layers ofclouds,when applicable;we restrict the cloud layersto a singlerepresentative layer, chosenbasedon a priority level. Broken”BKN” or overcast”OVC” layersare given the highestpriority,and thus the lowest layer of that type is chosenas the represen-tative. Scattered”SCT” layersare given the next priority level,followedby ”FEW”, andfinally none,or ”CLR” (for clear).Thus,the representative is the worst the pilot can expect to encounter.Both METARs andTAFs implementa similar cloudlayerscheme.Anothermuchlesslimiting simplificationis deletinginput formatcommentsassociatedwith METARs.

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,suchasfindingthe closestairport to an arbitrary lat/long position; getting theMETAR/TAF for an airport with reporting capability; getting arepresentative METAR/TAF for non-reportingairports;finding theclosestandsecondclosestwinds aloft forecasts;or keepingtrackof theuser’s chosenroute.Eachof thesemethodsis usedby otherfoundationclassesto helpprovidewhattheuserwants.

3.2 Graphical Interface and Displa y

The graphicsportion of AWE relieson the foundationclassestocomputewhatinformationto display. Wewill now discusshow wedisplay it. We begin by texturing the backgroundAWE windowwith our local areaof the SanFranciscoSectionalAeronauticalchartto give pilots a familiar environmentwith which to interact.Thechartshowsthelocationof airports,navigationaids,controlledandspecial(suchasrestricted)airspaces,obstructions,naturalter-rain features(suchaswaterandhills, depictedusingcolor codedaltitudes),andcongestedareas(suchascities,depictedin yellow).

Defining the Flight

Thepilot specifieshis routeof flight by selecting(with themouse)a sequenceof airports.10 The useris able to extendhis routebyaddinganairport to theend,modify his routeby deletingairportsoff the end until the modification point is reached(eventuallybacktrackingto thebeginningif desired),or specifyinganew route.As airportsareaddedor deleted,the interfaceis updatedto reflectthe currentspecifiedroute. The backgroundscreenwith a routeselectedby thepilot is shown in Figure2.

10As statedearlier, AWE doesnot currently recognizenavigation aidssuchasVORs.

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

Selecting Information Overla ys

A full versionof AWE would provide optionsto overlay all theinformation a pilot may want to view. This includes satelliteimages,temperaturecontours,etc. Becausemuchof that dataisalreadyeffectively visualizedby othersources,wesimplifiedAWEto restricthis optionsto a limited setof combinations.His optionsarelimited to:

� Displayfocus:areawideweathervs. routespecificweather;

� Typeof weather:currentweatherobservations(METAR) vs.forecastweather(TAF), and/orwindsaloft;

� Displayoptions:show closestavailableweatherand/orshowtextualor iconicview.

Display Focus: The pilot canchooseto displayweathereitherjust along his route of flight or for the entire area known byAWE. The areawide weatheroption is especiallyuseful duringthe 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 (possiblyall) airports that provide TAF forecastsalso provide METAR observations. Therefore,we implementedtheoptionsto displayMETARs or to displayTAFs to bemutuallyexclusive; that is, eitherMETARs or TAFs canbe displayed,butnot both simultaneously. Winds aloft, on the otherhand,providecomplementaryinformationto both sourcesandcanbe displayedeitheraloneor with aTAF or METAR. METARsandTAFsprovidesurfacewinds associatedwith the reportingairport. Winds aloftprovide windsat variousaltitudesandareassociatedwith a muchwiderareaaroundtheairport.

Display Option: Use closest: Not all airportsAWE knowsabouthave weatherreportingcapabilities. If the pilot is viewing routespecificweather, we provide him with the option of choosingtodisplaythenearestreport(of thesametype)for airportsthatfit thiscriteria. To accomplishthis, the pilot choosesthe ”show closestavailableweather”option.

Display Option: Show Icons: Onedisadvantageof displayingallavailableMETAR orTAF informationis theamountof screenspaceit occupies.This is typically not a major problemfor TAFs sinceonlyafew airportsprovidethatservice.Congestedareaswith manylocal airportsdo not fareaswell with METARs. As an example,theSanFranciscoBay Areahaseightairportsthat issueMETARsin the small areasurroundingthe bay. Thus,if the displayoptionis area-METARs, the advantageof providing all informationmayquickly turn into a problem,with METARs hiding eachother. Inthis situation, the pilot can still extract information provided bythe IFR/MVFR/VFR bordercodingschemediscussedbelow. Hecanquickly determinethe typeof conditionsdominatingthearea.He canalsoselectthe ”route-METAR” displayoption andselectairportsindividually to seetheparticulars.

AWE providesanoptionto attenuatetheclutter. For eitherTAFor METAR displays,thepilot canchooseto displaytheinformationusingcodediconsratherthantext, asshown in Figure3 anddis-cussedbelow. The icon displayprovidesonly enoughinformationto give the pilot a generalideaof the weatherconditions. Detailsareavailableonly whenhedeselectsthe”show icons”option.

Time-dependent Information: 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.

Choosing Appropriate Forecast: Determiningthe appropriateforecastis not assimplefor a computerasit is for a person.DU-ATs forecastsarenot specifiedasmutuallyexclusive time ranges.Rather, the generalforecast(given first) coversa 24 hour period.Forecastsfor morespecifictimesarethengiven.Eventhesespecifictimeperiodscanoverlap.For example,in aTAF file for theKSCK(Stocktonairport),wefind thatthreeforecastsmayapplyfor 10:30.First, thegeneralonethatspanstherange18:00on the18thof themonthto 18:00on the 19th statesthat the weatherwill be wind300@6,plus 6 statutemile (sm) visibility, sky clear� . Then, the”FM1000”, statesthatfrom 10:00,theweatherwill be wind calm,visibility of 1 smwith mist,sky clear� . Finally, the”TEMPO1015”statesthattherewill bea temporaryconditionfrom 10:00to 15:00of weather 1/4 sm visibility with fog, anda vertical visibility of200 feet� . AWE mustdeterminewhich oneof theseto presenttothe user. AWE choosesto presentthe worst scenario. Thus, inthis case,it choosesthe temporaryconditionasthe representativeweather.

Displa ying Information Overla ys

Wenow turn to thedisplayformats.Winds Aloft Display: Displayingwind informationis straightfor-

ward. We rotatethewind arrow to show thedirectionof thewindat that locationanddisplaythe wind speedalongside.If the pilothasrequestedareawide weather, AWE displaysall known windsaloft forecastsfor centralCalifornia. If the pilot requestsrouteweather, on theotherhand,wedisplaywind informationalongsideeachairportalonghisroute,interpolatedasdescribedbeforeandil-lustratedin Figure2. Displayingwindsaloft graphicallyallows theuserto quickly comparehis flight pathto thepathof thewind anddeterminewhetherto expecta tailwind, headwind,or crosswind.It helpshis situationalawarenessby giving him a direct pictureof expectedconditions. He canthencompensatefor a crosswindwithoutmuchthought,or expectto goslowerandusemorefuel forastrongheadwind.Becausewindsaloft arealtitudedependent,thepilot canmodify hisselectedaltitudeto determinewherethewindsaremostfavorable.Thedisplayis updatedin realtimeto reflecthisselection.

Textual METAR/TAF Display: Determininghow to display aMETAR or aTAF to make it easilydecipherableyetprovideall thenecessaryinformation is morecomplicated. The FAA approach,usedwith chartsavailableatFlight ServiceStations,arevery infor-mative,yetverycryptic. Theirsymbols,shown in Figure1, requirememorizationand can be easily forgotten if not usedregularly.Instead,we couldchooseto follow theWeatherChannelapproachand display only a small set of symbols. One disadvantageofthis approachis that much of the available information is notrepresented.

Wechoseto provide thepilot with all theinformationavailable.Thepilot hastheoptionto askfor all informationtextually attachednext to the airport or for only an iconic view that provides himwith a ”feel” for theweather, but no specifics.A textual displayofMETAR informationis shown in Figure2. An iconicrepresentationis similar to theTAF iconsshown in Figure3.

Tomakethetaskof recognizingconditionsquicker, werepresentthe wind directiongraphically(similar to the winds aloft display)aswell as textually. The pilot cannow easilycomparethe wind

Figure1: FAA weathersymbols.

directionwith the orientationof the runwaysasdisplayedon thesectional(AWE’s backgroundimage). Thus, crosswindlandingconditionsbecomevisuallyobvious.

Thetextualdisplaysaresupplementedwith color-codedbordersto warn the pilot of possibleadverseconditions. Recall that IFR,InstrumentFlight Rules,apply whenthe visibility is �� 3 milesor theceiling11 is �� 1000feet. Many pilots arepreventedeitherlegally (by not having appropriatecertification)or practically(bynot beingproficient)from landingat airportswith IFR conditions.MVFR conditionsareonly apractical,notalegal,determent(manypilots feel lesssafein marginalconditions).AWE displaysairportswith IFR conditionswith a redborder, airportswith MVFR with ayellow border, andthosewith VFR withoutaborder. Thepilot canthuseasilyseewherethewidespreadareasof low visibility or lowceilingsarelocated.A sample”route-METAR” displayis shown inFigure2.

Iconic METAR/TAF Display: Thereare four primary elementsthat affect a pilot’s ”go / no go” decision: wind conditions,visi-bility, cloud altitude, and temperature/ dew point spread. Windshear, turbulence,andstrongcrosswindsarepossibilitiesunderhighwind conditions. Temperatureand dew point can be importantin certainconditions. For instance,in the SF bay area,morningandevening fog is often a consideration.The temperature/ dewpoint spreadthenbecomesvaluableinformation. If the airport iscurrentlyexperiencingfog, thespreadgivesinformationonwhenitmayclear(especiallyif you have theprevioushour’s METAR andcanseea trendin how the spreadis changing). Similarly, in theheatof thesummer, temperatureis very importantat high altitudeairportssinceit hasadirecteffectonaircrafttakeoff characteristics.And, thoughthe authordoesnot have muchexperiencewith coldweather, very low temperaturesalsohave aneffect, not on takeoffbut on enginestart.They canalsocontributeto possibleice on theairframe. Usually, though,temperaturecanbe safelyclassifiedasnon-criticalinformationandis not representedin theiconicformat.Just as in the definition of IFR, MVFR, and VFR conditions,visibilities andcloudconditionsareprobablyconsideredthe mostimportantelements.

Our iconsaredesignedto presenta quick overview of the fourprimary elements.The icon is a triangle (modeledafter warningtriangles)that is subdivided into four triangles,eachrepresentingoneof theimportantelements.Thewind triangleis shown in whiteif the wind speedis lessthan15 knots,yellow if it’ s between15

11Ceiling is definedasabroken(BKN) or overcast(OVC) layer.

kts. and20 kts.,andredif it exceeds20 kts. Thevisibility triangleis shown in white if the visibility is greaterthan5 nm, yellow ifit’ s is between3 and5 nm, andred if it’ s is lessthanor equalto3 nm. The cloud altitudetriangle is shown in white if the lowestceiling layer is greaterthan 3000 feet, yellow if it’ s above 1000andbelow 3000feet,andred if it’ s at or below 1000feet. Finally,thetemperature/ dew point spreadtriangleis shown in white if thespreadis greaterthan4.5 degreesCelsius,yellow if it’ s between2 and4.5 degrees,andred if it’ s below 2 degrees.BecauseTAFsdo not provide temperatureor dew point forecasts,the TAF iconconsistsof just threetriangles.Thetemperature/ dew point spreadtriangleis alwaysshown in gray. In eachof thesecases,thecolorcodingservesonly to alertthepilot of possibleadverseconditions.The thresholdswerechosento coincidewith the FAA definitionsof IFR andMVFR conditionsfor visibility andceiling. The windspeedsandtemperaturedew point spreadswerechosenbasedon atypicalpilot andweatherprofile.

4 AWE Advantages

We have alreadymentionedseveral advantagesof AWE. A notimmediatelyapparentadvantageis for non-localpilots. Localpilotsknow the identifiers for most, if not all, the airportswithin 100miles. They canimmediatelypicturewheretheairport is, how farit is from their homeairport,andwhattheir flight pathwould looklike. Non-localpilots,on theotherhand,have amoredifficult timeinterpretinga DUATs areabriefing. They must refer to the chartor otherreferencematerialto determinewhich airportanidentifierrefersto, to visualizewhereairportsarelocated,to determinewhichairport is closestto onewithout a TAF, etc. All that informationisdirectly availableon AWE. They cannow visualizetheweatheraseasilyin adistantareaasthey canin their localarea.

Oneof theotherusefulaspectsof AWE is its useasa planningtool. AWE allowsthepilot to specifyhisairplane’s trueairspeed,toselectanaltitude,andto selecta departuretime. Any of thesecanbemodifiedduring theAWE session;METARs, TAFs, andwindsaloft areupdatedimmediatelyto reflectthenew selections.Thus,thepilot canchooseafavorablealtitude(e.g.,with moretailwinds),chooseto slow down andsave fuel if thewindswill let him arrivewithin a time window of his choice,or chooseto departearlierorlaterto usetheforecastto hisadvantage.Therecreationalpilot canevenuseAWE to decideon a directionfor his pleasureflight. Thecombinationof thesefeaturesmakes AWE a very useful tool forlocalandnon-localpilotsalike.

References

[1] ThomasA. Horne.Beaminguptheweather. AOPA Pilot, pages97–102,March2000.

[2] MIT. World Wide Web. cirrus.mit.edu/ gem-pak/forecastmaps.html.

[3] U.S.Departmentof Transportation.Aviation Weather: AC 00-6A. USGovernmentPrintingOffice,Washington,D.C.,1975.

[4] U.S.Departmentof Transportation.Aviation Weather Services:AC 00-45C. US GovernmentPrinting Office, Washington,D.C.,1985.

[5] Aviation Digital Data Service. World Wide Web.adds.awckc.noaa.gov/projects/adds/index.html.

[6] AviationWeather. World WideWeb. aviationweather.com.

Figure2: RouteMETARs andwindsaloft shown alongsidea pilot-selectedroute. The windsaloft directionis shown graphicallyandthewind speedis shown textually. Within theMETAR box,surfacewindsareshown graphicallyaswell astextually. Visibility, cloudaltitude,temperatureanddew point areonly shown textually. The METAR box borderdepictsinstrumentflight conditions(red border),marginalvisualflight conditions(yellow border),or visualconditions(noborder).

Figure3: AreaTAF displayusingtriangularicons.Thecolor in eachof thefour subtrianglesindicateadverse,marginal,or safeconditions.Theuppersubtriangledepictswind conditions;themiddlesubtriangledepictstemperature/dew pointspread;thelowerleft subtriangledepictscloudaltitudes;andthelower right subtriangledepictsvisibility conditions.