soaring forecasts: digging for data at nws web sites...2 figure 2: local nws forecast office...
TRANSCRIPT
1
December 2003 National Weather Service Volume 2 Number 3
Mission Statement
To enhance aviation safety byincreasing the pilotrsquos knowledge ofweather systems and processes andNational Weather Service productsand services
Managing Editor Michael GrafContributing Editor Craig SandersEditor MelodyMagnusnoaagov
Soaring Forecasts DiggingFor Data at NWS Web Sitesby Dan Shoemaker NWS Fort Worth TX
Figure 1 Mark Vaughn shows the exhilaration of hang gliding Obtaininggood weather data before each flight will only add to the experience
In this Issue
Soaring ForecastsDigging For Dataat NWS Web SitesSurface Analysis 1
Volcanic AshSignificant AviationHazard 5
Mark Vaughn photograhycopy
2003 Marksphotography
aolcomThe National Weather Service (NWS)
serves a broad base of aviation users thatinclude soaring pilots The main sourcesof information are TAFs from WeatherForecast Offices ldquoWFOsrdquo numerousproducts from the Aviation Weather Cen-ter ldquoAWCrdquo and the computer generatedguidance from the National Centers forEnvironmental Prediction ldquoNCEPrdquo
Specific NWS Forecast for soaring aremainly throughout the southwestern por-tion of the US But but wersquoll discussweather products and information thatassist making soaring forecast for otherlocations as savvy resourceful soaring pi-lots hangliders and paragliders enjoy im-mensely the thrill of letting the atmo-
sphere alone work to keep their refuge fromthe everyday world aloft
The soaring community is extensiveOne estimate puts the number around20000 pilots flying sailplanes hang glidersand paragliders As a group these pilots havehad to hone good meteorological sense tomaximize their soaring experience Itrsquos worthnoting that sailplanes have soared past thetropopause and hang gliders and paraglidershave reached altitudes above 18000 ft Hanggliders and paragliders routinely makeunpowered cross country trips of more than100 miles The current hang glider crosscountry record is over 400 miles All by tap-ping the resources of the free air without apowered assist after release
2
Figure 2 Local NWS forecast office locations Click on the dot to bring up thehome page for each office
Figure 3 New graphical digital forecasts are being developed by the NWS tosupplement text products
Soaring pilots get their lift from twomain sources terrain and instability Ridgeand wave soaring is done in the regiondownstream from mountains or otherprominent terrain Thermal soaring usesinstability in the free open atmosphere
Ridge or wave lift relies on wind risingover an obstruction such as a mountainand rising over it In a stable atmospherethese mountain waves can provide lift thatgoes above the tropopause as evidenced inSteve Fossettrsquos recent record attempts
Thermal soaring relies on air parcelsreleased by the sunrsquos heating of the groundThese parcels rise through the unstablelower layers and provide localized lift Thisform of soaring usually occurs below cloudbase VFR rules apply
These two mechanisms can be com-bined to prolong the flight A pilot can soaralong a ridge while waiting for thermals todevelop and provide extra lift for a cross-country flight
Thermal soaring in the US requiresknowledge of two different regions Dryareas in the west can provide thermal liftabove 18000 feet MSL Thermals tend tooffer higher vertical velocities and highercloud bases Terrain facing the sun will heatup and develop thermals during the morn-ing which supplements the lift providingby air flow toward and up the nearby slopes
East of the Mississippi River cloudbases are lower because of the higherdewpoints Most often the unstable con-ditions are found below the base of cumu-lus clouds which often is around 6000 feetMSL in the warm season
Getting into the air requires poweredassistance An aircraft will tow and release asailplane or paraglidger about 2000 feetabove ground level Ground towing with avehicle will work to get a glider between1500 and 2000 feet before releasing it
Before departure tow pilots need toknow the vertical wind profile to select run-ways and direction of flight Ground towsneed to select roads running in a directionfacing the wind A second concern for towand sailplane pilots is instability Will theair be soarable Does that air temperaturedecrease with height to provide instabilityor is a temperature inversion present whichwill suppress vertical motion Will thun-derstorms be a factor What is the bound-ary layer wind speed and direction Strongboundary layer winds can disrupt the de-sired vertical column of unstable air anddestroy thermal lift Winds may be toostrong to land safely Will there be cloudcover that will slow down surface heatingand thermal development To make flight
East-facing slopes develop thermal lift firstand west-facing slopes offer better soaringin the afternoon Soaring pilots must al-ways adjust their techniques to take advan-tage of these changing conditions
3
Figure 4 MOS tables give specifics on temperature dew point wind andother parameters useful for soaring
and precipitation type For a sample go tohttpwwwnwsnoaa govforecastsgraphical (Figure 3)
Model Output Statistics (MOS) aretables of numerical data containing specif-ics every three to six hours from the atmo-spheric models You can find these tablesat httpwwwnwsnoaagovmdlsynopproductsshtml (Figure 4) NWSruns a number of atmospheric modelsdaily Like aircraft that might look the samebut perform differently the atmosphericmodels the Eta and GFS each offer simi-lar but slightly different solutions to anevolving weather situation The Eta is arespected short term model The GFS is agood choice for longer range planning Theclickable tabs under each section on theMOS page takes to you pages where youcan select site-specific tables of data Yourown investigation of these tables will helpyou find the products most useful to you
A map is worth a thousand wordsespecially a day before a flight NCEP mod-els produce surface and upper air mapsshowing weather systems and the windsaloft Go to httpwwwnws noaagov
decisions pilots use all the information theycan get and they want it in usable form
Without specific soaring forecasts formany regions the Web has become a popu-lar source for weather dataPilots have to do theirhomework and search forthe data they need Soar-ing requires careful plan-ning days in advance
For outlooks morethan a day or two outNWS has the text-basedzone forecasts out toseven days These give aquick indication of skycondition temperaturewind and chances of pre-cipitation Your localNWS home page has aclickable ldquoLocal Forecastsrdquooption on the left handside To find your localoffice click on the map athttpwwwwrhnoaagovwrhqnwspagehtml (Figure 2)
NWS is developing anew graphical tool calledthe National Digital Fore-cast Database (NDFD)This may be the mainmethod by which NWSdelivers future products
But for now itrsquos experimental Like the zoneforecasts NDFD maps offer seven days ofgraphical data for sky cover winds tempera-ture humidity probability of precipitation
Figure 5 Upper air charts give good visual assessment of winds aloft that soaring pilots will face
4
and select ldquonumerical modelsrdquo to view theEta and GFS The RUC another short-term model on this page offers maps outto 12 hours based on with real time data
The maps show wind direction andspeed Air flow parallel to the lines andwind flags on the map show the directionwind is blowing The number of barbs orflags indicate speed Each barb is about 10knots and each flag represents 50 knots Atleast two model runs are made each day atNCEP 0000 UTC and 1200 UTC A tableis used to select maps
The numbers represent the hours af-ter the model run was made ie 018 fromthe 0000 UTC model run table is valid for1800 UTC the next day The same 018 choicemade for the 1200 UTC run would be validat about midnight on that night The validtime of each map is given at the bottomof each chart in UTC time Always checkthis valid time when studying the maps
Soaring pilots also study the vertical
structure of the air using soundings whichshow whether the air is unstable or if a tem-perature inversion is present You can findsoundings as shown in Figure 5 athttpwww-frdfslnoaagovmabsoundingsjava Once there enter hoursand site then click java for picture or ASCIIfor text Forecast soundings give a more in-depth look at the lower layers and a firstguess as to thermal activity as well as windsthat would influence decisions on what sideof a terrain feature to fly Also provided isthe stability indices such as the lifted indexldquoLIrdquo for the time of flight For more infor-mation on the Stability indices such as liftedindex review the May-June 2002 and July2003 isues of The Front
On the morning of a flight I look atMETARs TAFs satellite and radar imagesFor that the Aviation Digital Data Servicepage is THE place to go httpaddsaviationweathernoaagov Also checkshort-term soundings at the FSL site
Finally some WFOs mainly in thesouthwest issue soaring forecasts Checkhttpwwwwrhnoaagovrenoaviationindexshtml and click on ldquoRenosoaring forecastrdquo for an explanation of theforecast and terms To find your local WFOgo to httpweathergov and select yourlocal area At the bottom of the WFO siteis a ldquocontact usrdquo link where you can ask theWFO about initiating a soaring program
No single product or Website pro-vides all the data a soaring pilot need mightneed but the collective data will help makethe best decision Each flight and the prepa-ration time for it builds on this experienceand gives the soaring pilot the very keensense needed for an extended flight
Dan Shoemaker is a NWS forecaster atFort Worth and has been a soaring pilot for 20years Dan started flying hang gliders in theearly 1980s Hersquos flown ultralights and sailplanesHe even soared over Guam several years ago
Figure 6 Upper air soundings offer a wealth of information about the stability of the air and wind directions at many levels
5
by Dan Gregoria Forecaster NWS San Juan Puerto Rico
Volcanic AshSignificant Aviation Hazard
Figure 2 Damage to this jet turbine resulted from ingesting volcanic ashThe ash melted and formed an acidic glass-like coating on the engine
Figure 1 Looking as though a nuclear bomb exploded the Alaskarsquos RedoubtVolcano erupts
Volcanoes are awesome displays ofpower that throw gritty ash miles into theatmosphere
Volcanic ash suspended in the atmo-sphere presents a significant hazard to theaviation community Even in thin concen-trations ash poses a subtle threat to aircraftengines See Figure 1
Several agencies work together to alertpilots to this hazard The Anchorage Volca-nic Ash Advisory Center (VAAC) is one ofnine units in a worldwide monitoring net-work and is also a part of the Alaska Avia-tion Weather Unit Another VAAC in Wash-ington DC covers the remainder of thecontinental US the Caribbean and thenorthern portion of South America
The Aviation Weather Center in Kan-sas City MO provides SIGMETs for volca-nic ash in the continental US based on Vol-canic Ash Advisories from the VAACs Cen-ter Weather Service Units (CWSUs) FlightService Stations (FSSs) and the local WeatherForecast Office (WFO) near an active vol-cano all play their part in this awareness ac-tivity
Why all the fuss about volcanic ashThe term ash sounds pretty innocent but
this isnrsquot even close to the kind of ash youmight find in your fireplace or campfireVolcanic ash is a destructive substance com-
posed of fine pulverized rock and a num-ber of gases converted into droplets ofsulphuric acid and hydrochloric acid
This composition can significantlydamage an aircraft engine The ash may meltin the hot sections of the engine and fuseinto a thin coating on components fartherback creating the potential for completeengine failure Although piston-poweredaircraft are less likely to lose power whenencountering volcanic ash no aircraft isimmune to its danger See Figure 2
There have been several major aircraftencounters with volcanic ash In June 1982a British Airways 747 lost power in all fourengines and suffered severe damage whenit ingested ash from Mt Galunggung inIndonesia After losing power the planefell to 12000 feet before the crew was ableto restart the engines The plane made anemergency landing in Jakarta
Another major incident occurred nearAnchorage AK in 1989 when a wide-bodypassenger jet encountered a volcanic ashcloud All four engines failed putting theplane in a free fall from 25000 feet to 13000feet before the pilots were finally able torestart the engines The mountain tops inthe area where this plane descended reach
6
Figure 3 Tectonic plates are interlocking sections of the earth where seismic activity and volcanos are found
Figure 4 Satellites can track volcanic ash This view is from Alaska Note that it looks likesmoke from a forest fire or thin cirrus clouds but this hazard is far more dangerous thaneither one of those
nearly 11000 feet making thisincident an extremely close call
So where are pilots mostlikely to encounter volcanic ashVolcanoes concentrate aroundthe periphery of the earthrsquos tec-tonic plates interlocking sec-tions of continental land-masses Plate movement hasresulted in slowly drifting con-tinents and changes in the shapeand size of both ocean basinsand continents Where two ormore plates meet earthquakesand volcanoes are likelyFigure 3 depicts these interlock-ing plates
The highest density of ac-tive volcanoes extending fromeastern Asia to Alaska is knownas ldquoThe Ring of Firerdquo for goodreasons It is important for pi-lots to realize that ash can travelhundreds and even thousandsof miles from an active siteDuring one major eruption ofthe Redoubt Volcano in Alaskathe ash traveled all the way into
7
FVXX21 KWBC 190127VOLCANIC ASH ADVISORYISSUED 2003NOV190130Z VAAC WASHINGTON
VOLCANO COLIMA 1401-04LOCATION N1931W10337 AREA MEXICO
SUMMIT ELEVATION 13451 FT (4100 M)
ADVISORY NUMBER 200359
INFORMATION SOURCE GOES-12 IMAGERY MEXICO CITY MWOG F SMODEL WINDS FORECAST PILOT REPORT
ERUPTION DETAILS EXHALATION ABOUT 190000Z
OBS ASH DATETIME 190045
OBS ASH CLOUD SFCFL180 5 NM WIDE LINE EXTENDING BE-T W E E NN1931W10337 N1941W10327 ASH IS MOVING NE 5-10 KNOTS
FCST ASH CLOUD +6H SEE SIGMETS
REMARKS THE MEXICO CITY METEOROLOGICAL WATCH OFFICEREPORTED A POSSIBLE ASH PLUME FROM A PILOT REPORT THEYRECEIVED A VERY SUBTLE EXHALATION CAN BE SEEN ON THEL A S TVISIBLE IMAGES AND SUBSEQUENT MULTI-SPECTRAL IMAGERYSHOWEDA SMALL AREA OF ENHANCEMENT THAT WOULD CORRESPOND WITHW I N DINFORMATION AND OTHER REPORTS APPROXIMATED THE HEIGHTTO BEABOUT FL180NEXT ADVISORY WILL BE ISSUED BY 2003NOV190730Z
NNNNrdquoAttached Graphic Map Depicting Ash Onlyrdquo
A SIGMET for Volcanic Ash in Puerto Rico a short timeago looked like this
SIGMET BRAVO 4 VALID 200100200500 KKCI-SAN JUAN FIR VA WI AREA BOUNDED BY 1690N6283W 1753N6365W1727N6412W 1675N6338W VA BLO FL080 MOV NW 10KT BASEDON SAT OBS
Figure 5 Recent example of a Volcanic Ash Advisory
northern parts of the continental UnitedStates Eruptions in remote areas are noguarantee that region you fly in will be freeof ash-related hazards
In July 2001 the Soufriere Hills Vol-cano on the island of Montserrat in theCaribbean erupted and quickly sent ash overthe US Virgin Islands and Puerto RicoThe San Juan PR International Airportwas forced to close due to the volcanic ash
The ash actually covered the groundof Eastern Puerto Rico some 300 milesfrom the volcano itself A volcanic eventsimilar to the one in 2001 occurred in 1996and for the first time was detected by therecently installed Doppler radar at WFOSan Juan
What Can You DoHow can a pilot know when volcanic
ash is present even if no SIGMET is validat the time The Volcanic Ash AdvisoryCenter routinely issues Volcanic Ash Advi-sory Statements whenever ash is present inthe atmosphere These statements providean outline of the location of the volcanicash along with its movement
Volcanic ash is one of the criteria forSIGMETs issued by the Aviation WeatherCenter in addition to the more familiarSIGMETs for severe turbulence and icing
The ash hazard and its movement aredepicted the same way as other hazardsCWSUs along FSS communicate this in-formation to the pilots NWS ForecastOffices such as San Juan include ldquoVArdquo in aTAF when volcanic ash is expected to bepresent at a terminal site
A number of aviation products warn-ing of this hazard are issued for aviationusers Volcanic Ash Advisories use a for-mat all their own They provide locationand dispersion data not found in othertypes of SIGMETs Pilots may find theseproducts useful for monitoring You canfind this information at httpwwwssdnoaagovVAACmessageshtml
Figure 5 shows a recent example ofan advisory This particular product has agraphic to show the location
Volcanoes can be small pinpointsources or huge disasters like Mount St
Helenrsquos Finding these events is made easierwith high-resolution NOAA satellites andtrained scientists who monitor volcanic ashworldwide Some examples of events in2003 are available at NOAArsquos OperationalSignificant Event Imagery Website athttpwwwoseinoaagov
This resource also shows imagery forevents such as severe weather icebergs for-est fires and other hazards
Clearly volcanic ash is a danger to anypilot Monitoring the latest advisories andSIGMETs for volcanic ash will keep youaware and safe when you fly
2
Figure 2 Local NWS forecast office locations Click on the dot to bring up thehome page for each office
Figure 3 New graphical digital forecasts are being developed by the NWS tosupplement text products
Soaring pilots get their lift from twomain sources terrain and instability Ridgeand wave soaring is done in the regiondownstream from mountains or otherprominent terrain Thermal soaring usesinstability in the free open atmosphere
Ridge or wave lift relies on wind risingover an obstruction such as a mountainand rising over it In a stable atmospherethese mountain waves can provide lift thatgoes above the tropopause as evidenced inSteve Fossettrsquos recent record attempts
Thermal soaring relies on air parcelsreleased by the sunrsquos heating of the groundThese parcels rise through the unstablelower layers and provide localized lift Thisform of soaring usually occurs below cloudbase VFR rules apply
These two mechanisms can be com-bined to prolong the flight A pilot can soaralong a ridge while waiting for thermals todevelop and provide extra lift for a cross-country flight
Thermal soaring in the US requiresknowledge of two different regions Dryareas in the west can provide thermal liftabove 18000 feet MSL Thermals tend tooffer higher vertical velocities and highercloud bases Terrain facing the sun will heatup and develop thermals during the morn-ing which supplements the lift providingby air flow toward and up the nearby slopes
East of the Mississippi River cloudbases are lower because of the higherdewpoints Most often the unstable con-ditions are found below the base of cumu-lus clouds which often is around 6000 feetMSL in the warm season
Getting into the air requires poweredassistance An aircraft will tow and release asailplane or paraglidger about 2000 feetabove ground level Ground towing with avehicle will work to get a glider between1500 and 2000 feet before releasing it
Before departure tow pilots need toknow the vertical wind profile to select run-ways and direction of flight Ground towsneed to select roads running in a directionfacing the wind A second concern for towand sailplane pilots is instability Will theair be soarable Does that air temperaturedecrease with height to provide instabilityor is a temperature inversion present whichwill suppress vertical motion Will thun-derstorms be a factor What is the bound-ary layer wind speed and direction Strongboundary layer winds can disrupt the de-sired vertical column of unstable air anddestroy thermal lift Winds may be toostrong to land safely Will there be cloudcover that will slow down surface heatingand thermal development To make flight
East-facing slopes develop thermal lift firstand west-facing slopes offer better soaringin the afternoon Soaring pilots must al-ways adjust their techniques to take advan-tage of these changing conditions
3
Figure 4 MOS tables give specifics on temperature dew point wind andother parameters useful for soaring
and precipitation type For a sample go tohttpwwwnwsnoaa govforecastsgraphical (Figure 3)
Model Output Statistics (MOS) aretables of numerical data containing specif-ics every three to six hours from the atmo-spheric models You can find these tablesat httpwwwnwsnoaagovmdlsynopproductsshtml (Figure 4) NWSruns a number of atmospheric modelsdaily Like aircraft that might look the samebut perform differently the atmosphericmodels the Eta and GFS each offer simi-lar but slightly different solutions to anevolving weather situation The Eta is arespected short term model The GFS is agood choice for longer range planning Theclickable tabs under each section on theMOS page takes to you pages where youcan select site-specific tables of data Yourown investigation of these tables will helpyou find the products most useful to you
A map is worth a thousand wordsespecially a day before a flight NCEP mod-els produce surface and upper air mapsshowing weather systems and the windsaloft Go to httpwwwnws noaagov
decisions pilots use all the information theycan get and they want it in usable form
Without specific soaring forecasts formany regions the Web has become a popu-lar source for weather dataPilots have to do theirhomework and search forthe data they need Soar-ing requires careful plan-ning days in advance
For outlooks morethan a day or two outNWS has the text-basedzone forecasts out toseven days These give aquick indication of skycondition temperaturewind and chances of pre-cipitation Your localNWS home page has aclickable ldquoLocal Forecastsrdquooption on the left handside To find your localoffice click on the map athttpwwwwrhnoaagovwrhqnwspagehtml (Figure 2)
NWS is developing anew graphical tool calledthe National Digital Fore-cast Database (NDFD)This may be the mainmethod by which NWSdelivers future products
But for now itrsquos experimental Like the zoneforecasts NDFD maps offer seven days ofgraphical data for sky cover winds tempera-ture humidity probability of precipitation
Figure 5 Upper air charts give good visual assessment of winds aloft that soaring pilots will face
4
and select ldquonumerical modelsrdquo to view theEta and GFS The RUC another short-term model on this page offers maps outto 12 hours based on with real time data
The maps show wind direction andspeed Air flow parallel to the lines andwind flags on the map show the directionwind is blowing The number of barbs orflags indicate speed Each barb is about 10knots and each flag represents 50 knots Atleast two model runs are made each day atNCEP 0000 UTC and 1200 UTC A tableis used to select maps
The numbers represent the hours af-ter the model run was made ie 018 fromthe 0000 UTC model run table is valid for1800 UTC the next day The same 018 choicemade for the 1200 UTC run would be validat about midnight on that night The validtime of each map is given at the bottomof each chart in UTC time Always checkthis valid time when studying the maps
Soaring pilots also study the vertical
structure of the air using soundings whichshow whether the air is unstable or if a tem-perature inversion is present You can findsoundings as shown in Figure 5 athttpwww-frdfslnoaagovmabsoundingsjava Once there enter hoursand site then click java for picture or ASCIIfor text Forecast soundings give a more in-depth look at the lower layers and a firstguess as to thermal activity as well as windsthat would influence decisions on what sideof a terrain feature to fly Also provided isthe stability indices such as the lifted indexldquoLIrdquo for the time of flight For more infor-mation on the Stability indices such as liftedindex review the May-June 2002 and July2003 isues of The Front
On the morning of a flight I look atMETARs TAFs satellite and radar imagesFor that the Aviation Digital Data Servicepage is THE place to go httpaddsaviationweathernoaagov Also checkshort-term soundings at the FSL site
Finally some WFOs mainly in thesouthwest issue soaring forecasts Checkhttpwwwwrhnoaagovrenoaviationindexshtml and click on ldquoRenosoaring forecastrdquo for an explanation of theforecast and terms To find your local WFOgo to httpweathergov and select yourlocal area At the bottom of the WFO siteis a ldquocontact usrdquo link where you can ask theWFO about initiating a soaring program
No single product or Website pro-vides all the data a soaring pilot need mightneed but the collective data will help makethe best decision Each flight and the prepa-ration time for it builds on this experienceand gives the soaring pilot the very keensense needed for an extended flight
Dan Shoemaker is a NWS forecaster atFort Worth and has been a soaring pilot for 20years Dan started flying hang gliders in theearly 1980s Hersquos flown ultralights and sailplanesHe even soared over Guam several years ago
Figure 6 Upper air soundings offer a wealth of information about the stability of the air and wind directions at many levels
5
by Dan Gregoria Forecaster NWS San Juan Puerto Rico
Volcanic AshSignificant Aviation Hazard
Figure 2 Damage to this jet turbine resulted from ingesting volcanic ashThe ash melted and formed an acidic glass-like coating on the engine
Figure 1 Looking as though a nuclear bomb exploded the Alaskarsquos RedoubtVolcano erupts
Volcanoes are awesome displays ofpower that throw gritty ash miles into theatmosphere
Volcanic ash suspended in the atmo-sphere presents a significant hazard to theaviation community Even in thin concen-trations ash poses a subtle threat to aircraftengines See Figure 1
Several agencies work together to alertpilots to this hazard The Anchorage Volca-nic Ash Advisory Center (VAAC) is one ofnine units in a worldwide monitoring net-work and is also a part of the Alaska Avia-tion Weather Unit Another VAAC in Wash-ington DC covers the remainder of thecontinental US the Caribbean and thenorthern portion of South America
The Aviation Weather Center in Kan-sas City MO provides SIGMETs for volca-nic ash in the continental US based on Vol-canic Ash Advisories from the VAACs Cen-ter Weather Service Units (CWSUs) FlightService Stations (FSSs) and the local WeatherForecast Office (WFO) near an active vol-cano all play their part in this awareness ac-tivity
Why all the fuss about volcanic ashThe term ash sounds pretty innocent but
this isnrsquot even close to the kind of ash youmight find in your fireplace or campfireVolcanic ash is a destructive substance com-
posed of fine pulverized rock and a num-ber of gases converted into droplets ofsulphuric acid and hydrochloric acid
This composition can significantlydamage an aircraft engine The ash may meltin the hot sections of the engine and fuseinto a thin coating on components fartherback creating the potential for completeengine failure Although piston-poweredaircraft are less likely to lose power whenencountering volcanic ash no aircraft isimmune to its danger See Figure 2
There have been several major aircraftencounters with volcanic ash In June 1982a British Airways 747 lost power in all fourengines and suffered severe damage whenit ingested ash from Mt Galunggung inIndonesia After losing power the planefell to 12000 feet before the crew was ableto restart the engines The plane made anemergency landing in Jakarta
Another major incident occurred nearAnchorage AK in 1989 when a wide-bodypassenger jet encountered a volcanic ashcloud All four engines failed putting theplane in a free fall from 25000 feet to 13000feet before the pilots were finally able torestart the engines The mountain tops inthe area where this plane descended reach
6
Figure 3 Tectonic plates are interlocking sections of the earth where seismic activity and volcanos are found
Figure 4 Satellites can track volcanic ash This view is from Alaska Note that it looks likesmoke from a forest fire or thin cirrus clouds but this hazard is far more dangerous thaneither one of those
nearly 11000 feet making thisincident an extremely close call
So where are pilots mostlikely to encounter volcanic ashVolcanoes concentrate aroundthe periphery of the earthrsquos tec-tonic plates interlocking sec-tions of continental land-masses Plate movement hasresulted in slowly drifting con-tinents and changes in the shapeand size of both ocean basinsand continents Where two ormore plates meet earthquakesand volcanoes are likelyFigure 3 depicts these interlock-ing plates
The highest density of ac-tive volcanoes extending fromeastern Asia to Alaska is knownas ldquoThe Ring of Firerdquo for goodreasons It is important for pi-lots to realize that ash can travelhundreds and even thousandsof miles from an active siteDuring one major eruption ofthe Redoubt Volcano in Alaskathe ash traveled all the way into
7
FVXX21 KWBC 190127VOLCANIC ASH ADVISORYISSUED 2003NOV190130Z VAAC WASHINGTON
VOLCANO COLIMA 1401-04LOCATION N1931W10337 AREA MEXICO
SUMMIT ELEVATION 13451 FT (4100 M)
ADVISORY NUMBER 200359
INFORMATION SOURCE GOES-12 IMAGERY MEXICO CITY MWOG F SMODEL WINDS FORECAST PILOT REPORT
ERUPTION DETAILS EXHALATION ABOUT 190000Z
OBS ASH DATETIME 190045
OBS ASH CLOUD SFCFL180 5 NM WIDE LINE EXTENDING BE-T W E E NN1931W10337 N1941W10327 ASH IS MOVING NE 5-10 KNOTS
FCST ASH CLOUD +6H SEE SIGMETS
REMARKS THE MEXICO CITY METEOROLOGICAL WATCH OFFICEREPORTED A POSSIBLE ASH PLUME FROM A PILOT REPORT THEYRECEIVED A VERY SUBTLE EXHALATION CAN BE SEEN ON THEL A S TVISIBLE IMAGES AND SUBSEQUENT MULTI-SPECTRAL IMAGERYSHOWEDA SMALL AREA OF ENHANCEMENT THAT WOULD CORRESPOND WITHW I N DINFORMATION AND OTHER REPORTS APPROXIMATED THE HEIGHTTO BEABOUT FL180NEXT ADVISORY WILL BE ISSUED BY 2003NOV190730Z
NNNNrdquoAttached Graphic Map Depicting Ash Onlyrdquo
A SIGMET for Volcanic Ash in Puerto Rico a short timeago looked like this
SIGMET BRAVO 4 VALID 200100200500 KKCI-SAN JUAN FIR VA WI AREA BOUNDED BY 1690N6283W 1753N6365W1727N6412W 1675N6338W VA BLO FL080 MOV NW 10KT BASEDON SAT OBS
Figure 5 Recent example of a Volcanic Ash Advisory
northern parts of the continental UnitedStates Eruptions in remote areas are noguarantee that region you fly in will be freeof ash-related hazards
In July 2001 the Soufriere Hills Vol-cano on the island of Montserrat in theCaribbean erupted and quickly sent ash overthe US Virgin Islands and Puerto RicoThe San Juan PR International Airportwas forced to close due to the volcanic ash
The ash actually covered the groundof Eastern Puerto Rico some 300 milesfrom the volcano itself A volcanic eventsimilar to the one in 2001 occurred in 1996and for the first time was detected by therecently installed Doppler radar at WFOSan Juan
What Can You DoHow can a pilot know when volcanic
ash is present even if no SIGMET is validat the time The Volcanic Ash AdvisoryCenter routinely issues Volcanic Ash Advi-sory Statements whenever ash is present inthe atmosphere These statements providean outline of the location of the volcanicash along with its movement
Volcanic ash is one of the criteria forSIGMETs issued by the Aviation WeatherCenter in addition to the more familiarSIGMETs for severe turbulence and icing
The ash hazard and its movement aredepicted the same way as other hazardsCWSUs along FSS communicate this in-formation to the pilots NWS ForecastOffices such as San Juan include ldquoVArdquo in aTAF when volcanic ash is expected to bepresent at a terminal site
A number of aviation products warn-ing of this hazard are issued for aviationusers Volcanic Ash Advisories use a for-mat all their own They provide locationand dispersion data not found in othertypes of SIGMETs Pilots may find theseproducts useful for monitoring You canfind this information at httpwwwssdnoaagovVAACmessageshtml
Figure 5 shows a recent example ofan advisory This particular product has agraphic to show the location
Volcanoes can be small pinpointsources or huge disasters like Mount St
Helenrsquos Finding these events is made easierwith high-resolution NOAA satellites andtrained scientists who monitor volcanic ashworldwide Some examples of events in2003 are available at NOAArsquos OperationalSignificant Event Imagery Website athttpwwwoseinoaagov
This resource also shows imagery forevents such as severe weather icebergs for-est fires and other hazards
Clearly volcanic ash is a danger to anypilot Monitoring the latest advisories andSIGMETs for volcanic ash will keep youaware and safe when you fly
3
Figure 4 MOS tables give specifics on temperature dew point wind andother parameters useful for soaring
and precipitation type For a sample go tohttpwwwnwsnoaa govforecastsgraphical (Figure 3)
Model Output Statistics (MOS) aretables of numerical data containing specif-ics every three to six hours from the atmo-spheric models You can find these tablesat httpwwwnwsnoaagovmdlsynopproductsshtml (Figure 4) NWSruns a number of atmospheric modelsdaily Like aircraft that might look the samebut perform differently the atmosphericmodels the Eta and GFS each offer simi-lar but slightly different solutions to anevolving weather situation The Eta is arespected short term model The GFS is agood choice for longer range planning Theclickable tabs under each section on theMOS page takes to you pages where youcan select site-specific tables of data Yourown investigation of these tables will helpyou find the products most useful to you
A map is worth a thousand wordsespecially a day before a flight NCEP mod-els produce surface and upper air mapsshowing weather systems and the windsaloft Go to httpwwwnws noaagov
decisions pilots use all the information theycan get and they want it in usable form
Without specific soaring forecasts formany regions the Web has become a popu-lar source for weather dataPilots have to do theirhomework and search forthe data they need Soar-ing requires careful plan-ning days in advance
For outlooks morethan a day or two outNWS has the text-basedzone forecasts out toseven days These give aquick indication of skycondition temperaturewind and chances of pre-cipitation Your localNWS home page has aclickable ldquoLocal Forecastsrdquooption on the left handside To find your localoffice click on the map athttpwwwwrhnoaagovwrhqnwspagehtml (Figure 2)
NWS is developing anew graphical tool calledthe National Digital Fore-cast Database (NDFD)This may be the mainmethod by which NWSdelivers future products
But for now itrsquos experimental Like the zoneforecasts NDFD maps offer seven days ofgraphical data for sky cover winds tempera-ture humidity probability of precipitation
Figure 5 Upper air charts give good visual assessment of winds aloft that soaring pilots will face
4
and select ldquonumerical modelsrdquo to view theEta and GFS The RUC another short-term model on this page offers maps outto 12 hours based on with real time data
The maps show wind direction andspeed Air flow parallel to the lines andwind flags on the map show the directionwind is blowing The number of barbs orflags indicate speed Each barb is about 10knots and each flag represents 50 knots Atleast two model runs are made each day atNCEP 0000 UTC and 1200 UTC A tableis used to select maps
The numbers represent the hours af-ter the model run was made ie 018 fromthe 0000 UTC model run table is valid for1800 UTC the next day The same 018 choicemade for the 1200 UTC run would be validat about midnight on that night The validtime of each map is given at the bottomof each chart in UTC time Always checkthis valid time when studying the maps
Soaring pilots also study the vertical
structure of the air using soundings whichshow whether the air is unstable or if a tem-perature inversion is present You can findsoundings as shown in Figure 5 athttpwww-frdfslnoaagovmabsoundingsjava Once there enter hoursand site then click java for picture or ASCIIfor text Forecast soundings give a more in-depth look at the lower layers and a firstguess as to thermal activity as well as windsthat would influence decisions on what sideof a terrain feature to fly Also provided isthe stability indices such as the lifted indexldquoLIrdquo for the time of flight For more infor-mation on the Stability indices such as liftedindex review the May-June 2002 and July2003 isues of The Front
On the morning of a flight I look atMETARs TAFs satellite and radar imagesFor that the Aviation Digital Data Servicepage is THE place to go httpaddsaviationweathernoaagov Also checkshort-term soundings at the FSL site
Finally some WFOs mainly in thesouthwest issue soaring forecasts Checkhttpwwwwrhnoaagovrenoaviationindexshtml and click on ldquoRenosoaring forecastrdquo for an explanation of theforecast and terms To find your local WFOgo to httpweathergov and select yourlocal area At the bottom of the WFO siteis a ldquocontact usrdquo link where you can ask theWFO about initiating a soaring program
No single product or Website pro-vides all the data a soaring pilot need mightneed but the collective data will help makethe best decision Each flight and the prepa-ration time for it builds on this experienceand gives the soaring pilot the very keensense needed for an extended flight
Dan Shoemaker is a NWS forecaster atFort Worth and has been a soaring pilot for 20years Dan started flying hang gliders in theearly 1980s Hersquos flown ultralights and sailplanesHe even soared over Guam several years ago
Figure 6 Upper air soundings offer a wealth of information about the stability of the air and wind directions at many levels
5
by Dan Gregoria Forecaster NWS San Juan Puerto Rico
Volcanic AshSignificant Aviation Hazard
Figure 2 Damage to this jet turbine resulted from ingesting volcanic ashThe ash melted and formed an acidic glass-like coating on the engine
Figure 1 Looking as though a nuclear bomb exploded the Alaskarsquos RedoubtVolcano erupts
Volcanoes are awesome displays ofpower that throw gritty ash miles into theatmosphere
Volcanic ash suspended in the atmo-sphere presents a significant hazard to theaviation community Even in thin concen-trations ash poses a subtle threat to aircraftengines See Figure 1
Several agencies work together to alertpilots to this hazard The Anchorage Volca-nic Ash Advisory Center (VAAC) is one ofnine units in a worldwide monitoring net-work and is also a part of the Alaska Avia-tion Weather Unit Another VAAC in Wash-ington DC covers the remainder of thecontinental US the Caribbean and thenorthern portion of South America
The Aviation Weather Center in Kan-sas City MO provides SIGMETs for volca-nic ash in the continental US based on Vol-canic Ash Advisories from the VAACs Cen-ter Weather Service Units (CWSUs) FlightService Stations (FSSs) and the local WeatherForecast Office (WFO) near an active vol-cano all play their part in this awareness ac-tivity
Why all the fuss about volcanic ashThe term ash sounds pretty innocent but
this isnrsquot even close to the kind of ash youmight find in your fireplace or campfireVolcanic ash is a destructive substance com-
posed of fine pulverized rock and a num-ber of gases converted into droplets ofsulphuric acid and hydrochloric acid
This composition can significantlydamage an aircraft engine The ash may meltin the hot sections of the engine and fuseinto a thin coating on components fartherback creating the potential for completeengine failure Although piston-poweredaircraft are less likely to lose power whenencountering volcanic ash no aircraft isimmune to its danger See Figure 2
There have been several major aircraftencounters with volcanic ash In June 1982a British Airways 747 lost power in all fourengines and suffered severe damage whenit ingested ash from Mt Galunggung inIndonesia After losing power the planefell to 12000 feet before the crew was ableto restart the engines The plane made anemergency landing in Jakarta
Another major incident occurred nearAnchorage AK in 1989 when a wide-bodypassenger jet encountered a volcanic ashcloud All four engines failed putting theplane in a free fall from 25000 feet to 13000feet before the pilots were finally able torestart the engines The mountain tops inthe area where this plane descended reach
6
Figure 3 Tectonic plates are interlocking sections of the earth where seismic activity and volcanos are found
Figure 4 Satellites can track volcanic ash This view is from Alaska Note that it looks likesmoke from a forest fire or thin cirrus clouds but this hazard is far more dangerous thaneither one of those
nearly 11000 feet making thisincident an extremely close call
So where are pilots mostlikely to encounter volcanic ashVolcanoes concentrate aroundthe periphery of the earthrsquos tec-tonic plates interlocking sec-tions of continental land-masses Plate movement hasresulted in slowly drifting con-tinents and changes in the shapeand size of both ocean basinsand continents Where two ormore plates meet earthquakesand volcanoes are likelyFigure 3 depicts these interlock-ing plates
The highest density of ac-tive volcanoes extending fromeastern Asia to Alaska is knownas ldquoThe Ring of Firerdquo for goodreasons It is important for pi-lots to realize that ash can travelhundreds and even thousandsof miles from an active siteDuring one major eruption ofthe Redoubt Volcano in Alaskathe ash traveled all the way into
7
FVXX21 KWBC 190127VOLCANIC ASH ADVISORYISSUED 2003NOV190130Z VAAC WASHINGTON
VOLCANO COLIMA 1401-04LOCATION N1931W10337 AREA MEXICO
SUMMIT ELEVATION 13451 FT (4100 M)
ADVISORY NUMBER 200359
INFORMATION SOURCE GOES-12 IMAGERY MEXICO CITY MWOG F SMODEL WINDS FORECAST PILOT REPORT
ERUPTION DETAILS EXHALATION ABOUT 190000Z
OBS ASH DATETIME 190045
OBS ASH CLOUD SFCFL180 5 NM WIDE LINE EXTENDING BE-T W E E NN1931W10337 N1941W10327 ASH IS MOVING NE 5-10 KNOTS
FCST ASH CLOUD +6H SEE SIGMETS
REMARKS THE MEXICO CITY METEOROLOGICAL WATCH OFFICEREPORTED A POSSIBLE ASH PLUME FROM A PILOT REPORT THEYRECEIVED A VERY SUBTLE EXHALATION CAN BE SEEN ON THEL A S TVISIBLE IMAGES AND SUBSEQUENT MULTI-SPECTRAL IMAGERYSHOWEDA SMALL AREA OF ENHANCEMENT THAT WOULD CORRESPOND WITHW I N DINFORMATION AND OTHER REPORTS APPROXIMATED THE HEIGHTTO BEABOUT FL180NEXT ADVISORY WILL BE ISSUED BY 2003NOV190730Z
NNNNrdquoAttached Graphic Map Depicting Ash Onlyrdquo
A SIGMET for Volcanic Ash in Puerto Rico a short timeago looked like this
SIGMET BRAVO 4 VALID 200100200500 KKCI-SAN JUAN FIR VA WI AREA BOUNDED BY 1690N6283W 1753N6365W1727N6412W 1675N6338W VA BLO FL080 MOV NW 10KT BASEDON SAT OBS
Figure 5 Recent example of a Volcanic Ash Advisory
northern parts of the continental UnitedStates Eruptions in remote areas are noguarantee that region you fly in will be freeof ash-related hazards
In July 2001 the Soufriere Hills Vol-cano on the island of Montserrat in theCaribbean erupted and quickly sent ash overthe US Virgin Islands and Puerto RicoThe San Juan PR International Airportwas forced to close due to the volcanic ash
The ash actually covered the groundof Eastern Puerto Rico some 300 milesfrom the volcano itself A volcanic eventsimilar to the one in 2001 occurred in 1996and for the first time was detected by therecently installed Doppler radar at WFOSan Juan
What Can You DoHow can a pilot know when volcanic
ash is present even if no SIGMET is validat the time The Volcanic Ash AdvisoryCenter routinely issues Volcanic Ash Advi-sory Statements whenever ash is present inthe atmosphere These statements providean outline of the location of the volcanicash along with its movement
Volcanic ash is one of the criteria forSIGMETs issued by the Aviation WeatherCenter in addition to the more familiarSIGMETs for severe turbulence and icing
The ash hazard and its movement aredepicted the same way as other hazardsCWSUs along FSS communicate this in-formation to the pilots NWS ForecastOffices such as San Juan include ldquoVArdquo in aTAF when volcanic ash is expected to bepresent at a terminal site
A number of aviation products warn-ing of this hazard are issued for aviationusers Volcanic Ash Advisories use a for-mat all their own They provide locationand dispersion data not found in othertypes of SIGMETs Pilots may find theseproducts useful for monitoring You canfind this information at httpwwwssdnoaagovVAACmessageshtml
Figure 5 shows a recent example ofan advisory This particular product has agraphic to show the location
Volcanoes can be small pinpointsources or huge disasters like Mount St
Helenrsquos Finding these events is made easierwith high-resolution NOAA satellites andtrained scientists who monitor volcanic ashworldwide Some examples of events in2003 are available at NOAArsquos OperationalSignificant Event Imagery Website athttpwwwoseinoaagov
This resource also shows imagery forevents such as severe weather icebergs for-est fires and other hazards
Clearly volcanic ash is a danger to anypilot Monitoring the latest advisories andSIGMETs for volcanic ash will keep youaware and safe when you fly
4
and select ldquonumerical modelsrdquo to view theEta and GFS The RUC another short-term model on this page offers maps outto 12 hours based on with real time data
The maps show wind direction andspeed Air flow parallel to the lines andwind flags on the map show the directionwind is blowing The number of barbs orflags indicate speed Each barb is about 10knots and each flag represents 50 knots Atleast two model runs are made each day atNCEP 0000 UTC and 1200 UTC A tableis used to select maps
The numbers represent the hours af-ter the model run was made ie 018 fromthe 0000 UTC model run table is valid for1800 UTC the next day The same 018 choicemade for the 1200 UTC run would be validat about midnight on that night The validtime of each map is given at the bottomof each chart in UTC time Always checkthis valid time when studying the maps
Soaring pilots also study the vertical
structure of the air using soundings whichshow whether the air is unstable or if a tem-perature inversion is present You can findsoundings as shown in Figure 5 athttpwww-frdfslnoaagovmabsoundingsjava Once there enter hoursand site then click java for picture or ASCIIfor text Forecast soundings give a more in-depth look at the lower layers and a firstguess as to thermal activity as well as windsthat would influence decisions on what sideof a terrain feature to fly Also provided isthe stability indices such as the lifted indexldquoLIrdquo for the time of flight For more infor-mation on the Stability indices such as liftedindex review the May-June 2002 and July2003 isues of The Front
On the morning of a flight I look atMETARs TAFs satellite and radar imagesFor that the Aviation Digital Data Servicepage is THE place to go httpaddsaviationweathernoaagov Also checkshort-term soundings at the FSL site
Finally some WFOs mainly in thesouthwest issue soaring forecasts Checkhttpwwwwrhnoaagovrenoaviationindexshtml and click on ldquoRenosoaring forecastrdquo for an explanation of theforecast and terms To find your local WFOgo to httpweathergov and select yourlocal area At the bottom of the WFO siteis a ldquocontact usrdquo link where you can ask theWFO about initiating a soaring program
No single product or Website pro-vides all the data a soaring pilot need mightneed but the collective data will help makethe best decision Each flight and the prepa-ration time for it builds on this experienceand gives the soaring pilot the very keensense needed for an extended flight
Dan Shoemaker is a NWS forecaster atFort Worth and has been a soaring pilot for 20years Dan started flying hang gliders in theearly 1980s Hersquos flown ultralights and sailplanesHe even soared over Guam several years ago
Figure 6 Upper air soundings offer a wealth of information about the stability of the air and wind directions at many levels
5
by Dan Gregoria Forecaster NWS San Juan Puerto Rico
Volcanic AshSignificant Aviation Hazard
Figure 2 Damage to this jet turbine resulted from ingesting volcanic ashThe ash melted and formed an acidic glass-like coating on the engine
Figure 1 Looking as though a nuclear bomb exploded the Alaskarsquos RedoubtVolcano erupts
Volcanoes are awesome displays ofpower that throw gritty ash miles into theatmosphere
Volcanic ash suspended in the atmo-sphere presents a significant hazard to theaviation community Even in thin concen-trations ash poses a subtle threat to aircraftengines See Figure 1
Several agencies work together to alertpilots to this hazard The Anchorage Volca-nic Ash Advisory Center (VAAC) is one ofnine units in a worldwide monitoring net-work and is also a part of the Alaska Avia-tion Weather Unit Another VAAC in Wash-ington DC covers the remainder of thecontinental US the Caribbean and thenorthern portion of South America
The Aviation Weather Center in Kan-sas City MO provides SIGMETs for volca-nic ash in the continental US based on Vol-canic Ash Advisories from the VAACs Cen-ter Weather Service Units (CWSUs) FlightService Stations (FSSs) and the local WeatherForecast Office (WFO) near an active vol-cano all play their part in this awareness ac-tivity
Why all the fuss about volcanic ashThe term ash sounds pretty innocent but
this isnrsquot even close to the kind of ash youmight find in your fireplace or campfireVolcanic ash is a destructive substance com-
posed of fine pulverized rock and a num-ber of gases converted into droplets ofsulphuric acid and hydrochloric acid
This composition can significantlydamage an aircraft engine The ash may meltin the hot sections of the engine and fuseinto a thin coating on components fartherback creating the potential for completeengine failure Although piston-poweredaircraft are less likely to lose power whenencountering volcanic ash no aircraft isimmune to its danger See Figure 2
There have been several major aircraftencounters with volcanic ash In June 1982a British Airways 747 lost power in all fourengines and suffered severe damage whenit ingested ash from Mt Galunggung inIndonesia After losing power the planefell to 12000 feet before the crew was ableto restart the engines The plane made anemergency landing in Jakarta
Another major incident occurred nearAnchorage AK in 1989 when a wide-bodypassenger jet encountered a volcanic ashcloud All four engines failed putting theplane in a free fall from 25000 feet to 13000feet before the pilots were finally able torestart the engines The mountain tops inthe area where this plane descended reach
6
Figure 3 Tectonic plates are interlocking sections of the earth where seismic activity and volcanos are found
Figure 4 Satellites can track volcanic ash This view is from Alaska Note that it looks likesmoke from a forest fire or thin cirrus clouds but this hazard is far more dangerous thaneither one of those
nearly 11000 feet making thisincident an extremely close call
So where are pilots mostlikely to encounter volcanic ashVolcanoes concentrate aroundthe periphery of the earthrsquos tec-tonic plates interlocking sec-tions of continental land-masses Plate movement hasresulted in slowly drifting con-tinents and changes in the shapeand size of both ocean basinsand continents Where two ormore plates meet earthquakesand volcanoes are likelyFigure 3 depicts these interlock-ing plates
The highest density of ac-tive volcanoes extending fromeastern Asia to Alaska is knownas ldquoThe Ring of Firerdquo for goodreasons It is important for pi-lots to realize that ash can travelhundreds and even thousandsof miles from an active siteDuring one major eruption ofthe Redoubt Volcano in Alaskathe ash traveled all the way into
7
FVXX21 KWBC 190127VOLCANIC ASH ADVISORYISSUED 2003NOV190130Z VAAC WASHINGTON
VOLCANO COLIMA 1401-04LOCATION N1931W10337 AREA MEXICO
SUMMIT ELEVATION 13451 FT (4100 M)
ADVISORY NUMBER 200359
INFORMATION SOURCE GOES-12 IMAGERY MEXICO CITY MWOG F SMODEL WINDS FORECAST PILOT REPORT
ERUPTION DETAILS EXHALATION ABOUT 190000Z
OBS ASH DATETIME 190045
OBS ASH CLOUD SFCFL180 5 NM WIDE LINE EXTENDING BE-T W E E NN1931W10337 N1941W10327 ASH IS MOVING NE 5-10 KNOTS
FCST ASH CLOUD +6H SEE SIGMETS
REMARKS THE MEXICO CITY METEOROLOGICAL WATCH OFFICEREPORTED A POSSIBLE ASH PLUME FROM A PILOT REPORT THEYRECEIVED A VERY SUBTLE EXHALATION CAN BE SEEN ON THEL A S TVISIBLE IMAGES AND SUBSEQUENT MULTI-SPECTRAL IMAGERYSHOWEDA SMALL AREA OF ENHANCEMENT THAT WOULD CORRESPOND WITHW I N DINFORMATION AND OTHER REPORTS APPROXIMATED THE HEIGHTTO BEABOUT FL180NEXT ADVISORY WILL BE ISSUED BY 2003NOV190730Z
NNNNrdquoAttached Graphic Map Depicting Ash Onlyrdquo
A SIGMET for Volcanic Ash in Puerto Rico a short timeago looked like this
SIGMET BRAVO 4 VALID 200100200500 KKCI-SAN JUAN FIR VA WI AREA BOUNDED BY 1690N6283W 1753N6365W1727N6412W 1675N6338W VA BLO FL080 MOV NW 10KT BASEDON SAT OBS
Figure 5 Recent example of a Volcanic Ash Advisory
northern parts of the continental UnitedStates Eruptions in remote areas are noguarantee that region you fly in will be freeof ash-related hazards
In July 2001 the Soufriere Hills Vol-cano on the island of Montserrat in theCaribbean erupted and quickly sent ash overthe US Virgin Islands and Puerto RicoThe San Juan PR International Airportwas forced to close due to the volcanic ash
The ash actually covered the groundof Eastern Puerto Rico some 300 milesfrom the volcano itself A volcanic eventsimilar to the one in 2001 occurred in 1996and for the first time was detected by therecently installed Doppler radar at WFOSan Juan
What Can You DoHow can a pilot know when volcanic
ash is present even if no SIGMET is validat the time The Volcanic Ash AdvisoryCenter routinely issues Volcanic Ash Advi-sory Statements whenever ash is present inthe atmosphere These statements providean outline of the location of the volcanicash along with its movement
Volcanic ash is one of the criteria forSIGMETs issued by the Aviation WeatherCenter in addition to the more familiarSIGMETs for severe turbulence and icing
The ash hazard and its movement aredepicted the same way as other hazardsCWSUs along FSS communicate this in-formation to the pilots NWS ForecastOffices such as San Juan include ldquoVArdquo in aTAF when volcanic ash is expected to bepresent at a terminal site
A number of aviation products warn-ing of this hazard are issued for aviationusers Volcanic Ash Advisories use a for-mat all their own They provide locationand dispersion data not found in othertypes of SIGMETs Pilots may find theseproducts useful for monitoring You canfind this information at httpwwwssdnoaagovVAACmessageshtml
Figure 5 shows a recent example ofan advisory This particular product has agraphic to show the location
Volcanoes can be small pinpointsources or huge disasters like Mount St
Helenrsquos Finding these events is made easierwith high-resolution NOAA satellites andtrained scientists who monitor volcanic ashworldwide Some examples of events in2003 are available at NOAArsquos OperationalSignificant Event Imagery Website athttpwwwoseinoaagov
This resource also shows imagery forevents such as severe weather icebergs for-est fires and other hazards
Clearly volcanic ash is a danger to anypilot Monitoring the latest advisories andSIGMETs for volcanic ash will keep youaware and safe when you fly
5
by Dan Gregoria Forecaster NWS San Juan Puerto Rico
Volcanic AshSignificant Aviation Hazard
Figure 2 Damage to this jet turbine resulted from ingesting volcanic ashThe ash melted and formed an acidic glass-like coating on the engine
Figure 1 Looking as though a nuclear bomb exploded the Alaskarsquos RedoubtVolcano erupts
Volcanoes are awesome displays ofpower that throw gritty ash miles into theatmosphere
Volcanic ash suspended in the atmo-sphere presents a significant hazard to theaviation community Even in thin concen-trations ash poses a subtle threat to aircraftengines See Figure 1
Several agencies work together to alertpilots to this hazard The Anchorage Volca-nic Ash Advisory Center (VAAC) is one ofnine units in a worldwide monitoring net-work and is also a part of the Alaska Avia-tion Weather Unit Another VAAC in Wash-ington DC covers the remainder of thecontinental US the Caribbean and thenorthern portion of South America
The Aviation Weather Center in Kan-sas City MO provides SIGMETs for volca-nic ash in the continental US based on Vol-canic Ash Advisories from the VAACs Cen-ter Weather Service Units (CWSUs) FlightService Stations (FSSs) and the local WeatherForecast Office (WFO) near an active vol-cano all play their part in this awareness ac-tivity
Why all the fuss about volcanic ashThe term ash sounds pretty innocent but
this isnrsquot even close to the kind of ash youmight find in your fireplace or campfireVolcanic ash is a destructive substance com-
posed of fine pulverized rock and a num-ber of gases converted into droplets ofsulphuric acid and hydrochloric acid
This composition can significantlydamage an aircraft engine The ash may meltin the hot sections of the engine and fuseinto a thin coating on components fartherback creating the potential for completeengine failure Although piston-poweredaircraft are less likely to lose power whenencountering volcanic ash no aircraft isimmune to its danger See Figure 2
There have been several major aircraftencounters with volcanic ash In June 1982a British Airways 747 lost power in all fourengines and suffered severe damage whenit ingested ash from Mt Galunggung inIndonesia After losing power the planefell to 12000 feet before the crew was ableto restart the engines The plane made anemergency landing in Jakarta
Another major incident occurred nearAnchorage AK in 1989 when a wide-bodypassenger jet encountered a volcanic ashcloud All four engines failed putting theplane in a free fall from 25000 feet to 13000feet before the pilots were finally able torestart the engines The mountain tops inthe area where this plane descended reach
6
Figure 3 Tectonic plates are interlocking sections of the earth where seismic activity and volcanos are found
Figure 4 Satellites can track volcanic ash This view is from Alaska Note that it looks likesmoke from a forest fire or thin cirrus clouds but this hazard is far more dangerous thaneither one of those
nearly 11000 feet making thisincident an extremely close call
So where are pilots mostlikely to encounter volcanic ashVolcanoes concentrate aroundthe periphery of the earthrsquos tec-tonic plates interlocking sec-tions of continental land-masses Plate movement hasresulted in slowly drifting con-tinents and changes in the shapeand size of both ocean basinsand continents Where two ormore plates meet earthquakesand volcanoes are likelyFigure 3 depicts these interlock-ing plates
The highest density of ac-tive volcanoes extending fromeastern Asia to Alaska is knownas ldquoThe Ring of Firerdquo for goodreasons It is important for pi-lots to realize that ash can travelhundreds and even thousandsof miles from an active siteDuring one major eruption ofthe Redoubt Volcano in Alaskathe ash traveled all the way into
7
FVXX21 KWBC 190127VOLCANIC ASH ADVISORYISSUED 2003NOV190130Z VAAC WASHINGTON
VOLCANO COLIMA 1401-04LOCATION N1931W10337 AREA MEXICO
SUMMIT ELEVATION 13451 FT (4100 M)
ADVISORY NUMBER 200359
INFORMATION SOURCE GOES-12 IMAGERY MEXICO CITY MWOG F SMODEL WINDS FORECAST PILOT REPORT
ERUPTION DETAILS EXHALATION ABOUT 190000Z
OBS ASH DATETIME 190045
OBS ASH CLOUD SFCFL180 5 NM WIDE LINE EXTENDING BE-T W E E NN1931W10337 N1941W10327 ASH IS MOVING NE 5-10 KNOTS
FCST ASH CLOUD +6H SEE SIGMETS
REMARKS THE MEXICO CITY METEOROLOGICAL WATCH OFFICEREPORTED A POSSIBLE ASH PLUME FROM A PILOT REPORT THEYRECEIVED A VERY SUBTLE EXHALATION CAN BE SEEN ON THEL A S TVISIBLE IMAGES AND SUBSEQUENT MULTI-SPECTRAL IMAGERYSHOWEDA SMALL AREA OF ENHANCEMENT THAT WOULD CORRESPOND WITHW I N DINFORMATION AND OTHER REPORTS APPROXIMATED THE HEIGHTTO BEABOUT FL180NEXT ADVISORY WILL BE ISSUED BY 2003NOV190730Z
NNNNrdquoAttached Graphic Map Depicting Ash Onlyrdquo
A SIGMET for Volcanic Ash in Puerto Rico a short timeago looked like this
SIGMET BRAVO 4 VALID 200100200500 KKCI-SAN JUAN FIR VA WI AREA BOUNDED BY 1690N6283W 1753N6365W1727N6412W 1675N6338W VA BLO FL080 MOV NW 10KT BASEDON SAT OBS
Figure 5 Recent example of a Volcanic Ash Advisory
northern parts of the continental UnitedStates Eruptions in remote areas are noguarantee that region you fly in will be freeof ash-related hazards
In July 2001 the Soufriere Hills Vol-cano on the island of Montserrat in theCaribbean erupted and quickly sent ash overthe US Virgin Islands and Puerto RicoThe San Juan PR International Airportwas forced to close due to the volcanic ash
The ash actually covered the groundof Eastern Puerto Rico some 300 milesfrom the volcano itself A volcanic eventsimilar to the one in 2001 occurred in 1996and for the first time was detected by therecently installed Doppler radar at WFOSan Juan
What Can You DoHow can a pilot know when volcanic
ash is present even if no SIGMET is validat the time The Volcanic Ash AdvisoryCenter routinely issues Volcanic Ash Advi-sory Statements whenever ash is present inthe atmosphere These statements providean outline of the location of the volcanicash along with its movement
Volcanic ash is one of the criteria forSIGMETs issued by the Aviation WeatherCenter in addition to the more familiarSIGMETs for severe turbulence and icing
The ash hazard and its movement aredepicted the same way as other hazardsCWSUs along FSS communicate this in-formation to the pilots NWS ForecastOffices such as San Juan include ldquoVArdquo in aTAF when volcanic ash is expected to bepresent at a terminal site
A number of aviation products warn-ing of this hazard are issued for aviationusers Volcanic Ash Advisories use a for-mat all their own They provide locationand dispersion data not found in othertypes of SIGMETs Pilots may find theseproducts useful for monitoring You canfind this information at httpwwwssdnoaagovVAACmessageshtml
Figure 5 shows a recent example ofan advisory This particular product has agraphic to show the location
Volcanoes can be small pinpointsources or huge disasters like Mount St
Helenrsquos Finding these events is made easierwith high-resolution NOAA satellites andtrained scientists who monitor volcanic ashworldwide Some examples of events in2003 are available at NOAArsquos OperationalSignificant Event Imagery Website athttpwwwoseinoaagov
This resource also shows imagery forevents such as severe weather icebergs for-est fires and other hazards
Clearly volcanic ash is a danger to anypilot Monitoring the latest advisories andSIGMETs for volcanic ash will keep youaware and safe when you fly
6
Figure 3 Tectonic plates are interlocking sections of the earth where seismic activity and volcanos are found
Figure 4 Satellites can track volcanic ash This view is from Alaska Note that it looks likesmoke from a forest fire or thin cirrus clouds but this hazard is far more dangerous thaneither one of those
nearly 11000 feet making thisincident an extremely close call
So where are pilots mostlikely to encounter volcanic ashVolcanoes concentrate aroundthe periphery of the earthrsquos tec-tonic plates interlocking sec-tions of continental land-masses Plate movement hasresulted in slowly drifting con-tinents and changes in the shapeand size of both ocean basinsand continents Where two ormore plates meet earthquakesand volcanoes are likelyFigure 3 depicts these interlock-ing plates
The highest density of ac-tive volcanoes extending fromeastern Asia to Alaska is knownas ldquoThe Ring of Firerdquo for goodreasons It is important for pi-lots to realize that ash can travelhundreds and even thousandsof miles from an active siteDuring one major eruption ofthe Redoubt Volcano in Alaskathe ash traveled all the way into
7
FVXX21 KWBC 190127VOLCANIC ASH ADVISORYISSUED 2003NOV190130Z VAAC WASHINGTON
VOLCANO COLIMA 1401-04LOCATION N1931W10337 AREA MEXICO
SUMMIT ELEVATION 13451 FT (4100 M)
ADVISORY NUMBER 200359
INFORMATION SOURCE GOES-12 IMAGERY MEXICO CITY MWOG F SMODEL WINDS FORECAST PILOT REPORT
ERUPTION DETAILS EXHALATION ABOUT 190000Z
OBS ASH DATETIME 190045
OBS ASH CLOUD SFCFL180 5 NM WIDE LINE EXTENDING BE-T W E E NN1931W10337 N1941W10327 ASH IS MOVING NE 5-10 KNOTS
FCST ASH CLOUD +6H SEE SIGMETS
REMARKS THE MEXICO CITY METEOROLOGICAL WATCH OFFICEREPORTED A POSSIBLE ASH PLUME FROM A PILOT REPORT THEYRECEIVED A VERY SUBTLE EXHALATION CAN BE SEEN ON THEL A S TVISIBLE IMAGES AND SUBSEQUENT MULTI-SPECTRAL IMAGERYSHOWEDA SMALL AREA OF ENHANCEMENT THAT WOULD CORRESPOND WITHW I N DINFORMATION AND OTHER REPORTS APPROXIMATED THE HEIGHTTO BEABOUT FL180NEXT ADVISORY WILL BE ISSUED BY 2003NOV190730Z
NNNNrdquoAttached Graphic Map Depicting Ash Onlyrdquo
A SIGMET for Volcanic Ash in Puerto Rico a short timeago looked like this
SIGMET BRAVO 4 VALID 200100200500 KKCI-SAN JUAN FIR VA WI AREA BOUNDED BY 1690N6283W 1753N6365W1727N6412W 1675N6338W VA BLO FL080 MOV NW 10KT BASEDON SAT OBS
Figure 5 Recent example of a Volcanic Ash Advisory
northern parts of the continental UnitedStates Eruptions in remote areas are noguarantee that region you fly in will be freeof ash-related hazards
In July 2001 the Soufriere Hills Vol-cano on the island of Montserrat in theCaribbean erupted and quickly sent ash overthe US Virgin Islands and Puerto RicoThe San Juan PR International Airportwas forced to close due to the volcanic ash
The ash actually covered the groundof Eastern Puerto Rico some 300 milesfrom the volcano itself A volcanic eventsimilar to the one in 2001 occurred in 1996and for the first time was detected by therecently installed Doppler radar at WFOSan Juan
What Can You DoHow can a pilot know when volcanic
ash is present even if no SIGMET is validat the time The Volcanic Ash AdvisoryCenter routinely issues Volcanic Ash Advi-sory Statements whenever ash is present inthe atmosphere These statements providean outline of the location of the volcanicash along with its movement
Volcanic ash is one of the criteria forSIGMETs issued by the Aviation WeatherCenter in addition to the more familiarSIGMETs for severe turbulence and icing
The ash hazard and its movement aredepicted the same way as other hazardsCWSUs along FSS communicate this in-formation to the pilots NWS ForecastOffices such as San Juan include ldquoVArdquo in aTAF when volcanic ash is expected to bepresent at a terminal site
A number of aviation products warn-ing of this hazard are issued for aviationusers Volcanic Ash Advisories use a for-mat all their own They provide locationand dispersion data not found in othertypes of SIGMETs Pilots may find theseproducts useful for monitoring You canfind this information at httpwwwssdnoaagovVAACmessageshtml
Figure 5 shows a recent example ofan advisory This particular product has agraphic to show the location
Volcanoes can be small pinpointsources or huge disasters like Mount St
Helenrsquos Finding these events is made easierwith high-resolution NOAA satellites andtrained scientists who monitor volcanic ashworldwide Some examples of events in2003 are available at NOAArsquos OperationalSignificant Event Imagery Website athttpwwwoseinoaagov
This resource also shows imagery forevents such as severe weather icebergs for-est fires and other hazards
Clearly volcanic ash is a danger to anypilot Monitoring the latest advisories andSIGMETs for volcanic ash will keep youaware and safe when you fly
7
FVXX21 KWBC 190127VOLCANIC ASH ADVISORYISSUED 2003NOV190130Z VAAC WASHINGTON
VOLCANO COLIMA 1401-04LOCATION N1931W10337 AREA MEXICO
SUMMIT ELEVATION 13451 FT (4100 M)
ADVISORY NUMBER 200359
INFORMATION SOURCE GOES-12 IMAGERY MEXICO CITY MWOG F SMODEL WINDS FORECAST PILOT REPORT
ERUPTION DETAILS EXHALATION ABOUT 190000Z
OBS ASH DATETIME 190045
OBS ASH CLOUD SFCFL180 5 NM WIDE LINE EXTENDING BE-T W E E NN1931W10337 N1941W10327 ASH IS MOVING NE 5-10 KNOTS
FCST ASH CLOUD +6H SEE SIGMETS
REMARKS THE MEXICO CITY METEOROLOGICAL WATCH OFFICEREPORTED A POSSIBLE ASH PLUME FROM A PILOT REPORT THEYRECEIVED A VERY SUBTLE EXHALATION CAN BE SEEN ON THEL A S TVISIBLE IMAGES AND SUBSEQUENT MULTI-SPECTRAL IMAGERYSHOWEDA SMALL AREA OF ENHANCEMENT THAT WOULD CORRESPOND WITHW I N DINFORMATION AND OTHER REPORTS APPROXIMATED THE HEIGHTTO BEABOUT FL180NEXT ADVISORY WILL BE ISSUED BY 2003NOV190730Z
NNNNrdquoAttached Graphic Map Depicting Ash Onlyrdquo
A SIGMET for Volcanic Ash in Puerto Rico a short timeago looked like this
SIGMET BRAVO 4 VALID 200100200500 KKCI-SAN JUAN FIR VA WI AREA BOUNDED BY 1690N6283W 1753N6365W1727N6412W 1675N6338W VA BLO FL080 MOV NW 10KT BASEDON SAT OBS
Figure 5 Recent example of a Volcanic Ash Advisory
northern parts of the continental UnitedStates Eruptions in remote areas are noguarantee that region you fly in will be freeof ash-related hazards
In July 2001 the Soufriere Hills Vol-cano on the island of Montserrat in theCaribbean erupted and quickly sent ash overthe US Virgin Islands and Puerto RicoThe San Juan PR International Airportwas forced to close due to the volcanic ash
The ash actually covered the groundof Eastern Puerto Rico some 300 milesfrom the volcano itself A volcanic eventsimilar to the one in 2001 occurred in 1996and for the first time was detected by therecently installed Doppler radar at WFOSan Juan
What Can You DoHow can a pilot know when volcanic
ash is present even if no SIGMET is validat the time The Volcanic Ash AdvisoryCenter routinely issues Volcanic Ash Advi-sory Statements whenever ash is present inthe atmosphere These statements providean outline of the location of the volcanicash along with its movement
Volcanic ash is one of the criteria forSIGMETs issued by the Aviation WeatherCenter in addition to the more familiarSIGMETs for severe turbulence and icing
The ash hazard and its movement aredepicted the same way as other hazardsCWSUs along FSS communicate this in-formation to the pilots NWS ForecastOffices such as San Juan include ldquoVArdquo in aTAF when volcanic ash is expected to bepresent at a terminal site
A number of aviation products warn-ing of this hazard are issued for aviationusers Volcanic Ash Advisories use a for-mat all their own They provide locationand dispersion data not found in othertypes of SIGMETs Pilots may find theseproducts useful for monitoring You canfind this information at httpwwwssdnoaagovVAACmessageshtml
Figure 5 shows a recent example ofan advisory This particular product has agraphic to show the location
Volcanoes can be small pinpointsources or huge disasters like Mount St
Helenrsquos Finding these events is made easierwith high-resolution NOAA satellites andtrained scientists who monitor volcanic ashworldwide Some examples of events in2003 are available at NOAArsquos OperationalSignificant Event Imagery Website athttpwwwoseinoaagov
This resource also shows imagery forevents such as severe weather icebergs for-est fires and other hazards
Clearly volcanic ash is a danger to anypilot Monitoring the latest advisories andSIGMETs for volcanic ash will keep youaware and safe when you fly