AAD D V V ANCESANCES ININ VOCANIC ASH AVOIDANCEAVOIDANCE ANDAND RECOVERYRECOVERY A commercial airplane encounter with volcanic ash can threaten safety of fligh t because of res u l t i n g conditions that range from wind- shield pitting to loss of thrust in all engines. Developments in technology and communication networks have significantly decreased the probability of such an encounter in the last several ye a r s . Despite these dev e l o p me nt s , however, a 737-700 recently flew through a volcanic ash cloud. Updated information about advancements made in ensuring A E R O 19 safe operations and minimizing S A F E T Y

THOMAS J. CASADEVALL, PH.D. damage to the airplane during DEPUTY DIRECTO R U.S. GEOLOGICAL SURVEY a volcanic ash encounter is now THOMAS M. MURRAY SAFETY ENGINEERING ANALY S T AIRPLANE PERFORMANCE available to flight crews. AND PROPULSION BOEING COMMERCIAL AIRPLANES GROUP Mt. Redoubt, United States, 1989. n the past 30 years, mo re than 90 jet-powered comme rc ia l ai r p l a n es have enco u nt e r ed clouds of volcanic ash and suffered On a flig ht from Ams t e rdam to Anc ho ra g e, Alaska, a new 747-400 damage as a result. The increased availability of satellites and (only three months old with approxi- I the technology to transform satellite data into useful informa- mately 900 hr total flying time) ti on for operators have red uced the number of volcanic ash enco u nt e r s . encountered an ash cloud from the Ho w e v e r, further coord i na t ion and coopera t ion, inc l ud i ng linking erupting Mt. Redoubt near Anchorage. o p e rators and their dispatchers to the network of government volcano All four engines ingested ash and observers, is required throughout the industry. Boeing has always flamed out. The crew successfully advocated that flight crews avoid volcanic ash clouds or exit them restarted the engi n es and landed safely immediately if an encounter occurs. The company also recommends at Anchorage. specific procedures for flight crews to follow if they cannot avoid an All four engines were replaced and encounter. many airplane systems also had to be repaired or replaced. For example, the Flight crews will be better prepared to avoid volcanic ash clouds and airplane environmental control system take the appropriate actions during an encounter if they understand was replaced (see below), the fuel the following information: tanks were cleaned, and the hydraulic 1. Results of past events involving volcanic ash. systems were repaired. Several other airplanes encountered ash from this 2. Resources available to help avoid ash encounters. eruption, but most damage was minor 3. Specific flight crew actions required in response to encounters. because operators had been notified of the eruption. Some operators, such RESULTS OF PAST EVENTS INVOLVING VOLCANIC ASH as Alaska Airlines , conti n ued schedu l e d 1 flights once they developed processes Sig n i f ic a n t ash enco u n ters from the past incl u de those involving such well-know n to safely identify where ash might be volcanoes as Mt. Pinatubo, Mt. Redoubt, and Mt. St. Helens. The airplanes that encountered. Although information encountered volcanic ash during these events and in the other events listed was available about the Mt. Redoubt chronologically experienced varying degrees of damage. eruption, the channels for sharing this information were not well developed at the time (see “Alaska Airlines Mt. St. Helens, United States, 1980. four engines were restarted. The air- Procedures for Operating in Volcanic A 727 and a DC-8 enco u nt e r ed separat e plane, on a flight from Kuala Lumpur, Ash Conditions” on p. 25). ash clouds during this major eruption. Malaysia, to Perth, Australia, diverted Both airplanes experienced damage to to Jakarta and landed safely despite Mt. Pinatubo, Philippines, 1991. their windshields and to several sys- major engine damage. This airplane More than 20 volcanic ash encounters tems, but both landed safely despite subsequently had all four engines occurred after the Mt. Pinatubo erup- the windshield damage. replaced befo re re t u r n i ng to servic e. tion, which was the largest volcanic A few days after the initial enco u nt e r s , eruption of the past 50 years. The Galunggung volcano, Indonesia, 1982. another 747 flew into the ash cloud ability to predict where ash was to be Several 747s encountered ash from an d suffered sign i f ic a n t engi n e dama g e. found was challenging because of the this eruption. One airplane lost thrust This airplane also diverted to Jakarta enormous extent of the ash cloud. from all four engines and descended and subsequently performed a success- Commercial flights and various military from 36,000 ft to 12,500 ft before all ful two-engine landing. operations were affected; one U.S.

Engine damage from ash ingestion Environmental control system damage Electrical panel damage

A E R O 20 1 VAAC REGIONS FIGURE

RESOURCES AVAILABLE TO Act i v i t i es on Vol c a n i c Ash” on page 26. 2 HELP AVOID ASH ENCOUNTERS One of the outcomes of this initial Although some information about vol- meeting is the availability of today’s canic eruptions has been available for Volcanic Ash Advisory Centers (VAAC). many years, the aviation industry and The VAACs provide an important link volcanological community began a amo n g volcano observatorie s, me t e o r- jo i n t effort to find ways to avoid future o l o g ical age nc ie s, air tra f f ic contro l e nc o u nters after the Mt. Redo u b t c e nt e r s, and opera t o r s. A total of Space shuttle image of volcanic eruption er u p t i on. At an inte r na t io n al conferenc e n i ne VAACs observe and report on a operator grounded its airplanes in in Seattle, Washington, in July 1991, pa r t ic u l a r reg io n of th e world (fig. 1). Manila for several days. aviation industry members, meteorolo- One product of the VAACs is the gists, and volcano scientists gathered Vo l c a n ic Ash Advisory Stateme nt Mt. Popocatepetl, Mexico, 1997. to determine what volcano event (VAAS). Below is an example of a VAAS This volcano affected several flights in information the aviation industry for a recent event in 1999. 1997 and 1998. Although damage was needed, how this information could be minor in most cases, one flight crew di s t r i b u t e d , and who or which agenc ie s ex p e r ie nced sig n i f ic a ntly re duced should distribute it. The v i s ibility for landing and had to look International Civil Aviation through the flight deck side windows Organization (ICAO) had laid to taxi after landing. In addition, the much of the foundation for airport in Mexico City was closed for the volcanic ash issue through up to 24 hr on several occasion s dur i n g its Volcanic Ash Warnings subsequent intermittent eruptions. Study Group; see “ICAO

A E R O 21 to access the site if it is overloaded dur i n g a crisis, the AVO daily telephon e recording at 907-786-7477 provides br i ef updated infor ma t io n fo ra i r ca r r ie r s . Finally, many operators maintain per- sonal relationships with ind i v i duals in th e volcano observatories that monitor volcanoes within a particular flight domain. For instance, Alaska Airlines maintains contact with key individuals at the AVO because a sig n i f ic a nt p o rtion of Alaska’s flight domain could be affected by Alaskan volcanoes. Man y other web sites prov i de infor m a- t ion and links to other sources of v o l c a no info r ma t io n (see “Vo l c a n ic Ash Resources” on p. 27). A wealth of printed information, such as the B u l l e t i n of the G l o b a l Vo l c a n i s m N e t w o r k through the Smithsonian National Museum of Natural History in Washington, D.C., is also available. How e v e r , the infor ma t i on about curren t vo l c a n i c activity in the s e pr i n ted source s is often two to three mont h s old. Geostationary operational environmental satellite detection and tracking of volcanic ash cloud from an eruption of Bezymianny volcano, Russia, that began at 7:00 a.m. on Feb. 24, 1999. The red triangle indicates the volcano location. Highest ash concentra- tions are indicated in orange and yellow. The blue areas on 0000Z and 0800Z are noise and do not indicate ash. The cloud was tracked at 15-min increments for 1,500 km until it dispersed beyond the limits of detection.

In addi t i on to prov id i n g VAASs direc t l y issued freq u e n tly as condi t io n s change. to the airlines, the VAACs also provide Anyone can request to be placed on information to appropriate meteoro- distribution for the bulletins. The AVO logical organizations that subsequently web site (http://www.avo.alaska.edu/) issue significant meteorological infor- also provides updated information. For mation (SIGMET) and other reports. th ose without Inte r n et access or unab l e The ICAO publication “International Airways Vol c a n o Wa t c h ”( IC AO an n ex II I ) c o nt a i ns further info r ma t ion and c o ntact names and numbers. Detailed information on the VAACs, including contacts for each of the nine centers, is available at http://www.ssd.noaa. gov/VAAC/. O p e rators rely on the VA ACs fo r i n fo r ma t ion, and ma ny opera t o r s ma i ntain direct contact with volcano observatories within their flight domains. For instance, the Alaska Vol c a n o Observatory (AVO) in Ancho ra g e, Re p o rt s can indicate whether the activity with links to Fairbanks, issues a is steam, as shown above, or ash. weekly bulletin by e-mail and fax Right: Geologists from the AVO examine detailing the activity of key volcanoes fr esh pyroclastic flow from Mt. Redoubt, in Alaska. During periods of volcanic Mar. 23, 1990. unrest and eruption, bulletins are

A E R O 22 3 SPECIFIC FLIGHT CREW ACTIONS REQUIRED IN RESPONSE TO ENCOUNTERS Despite ongoing avoidance efforts, operators can still experience volcanic ash encounters. Guidance on the operational issues surrounding volcanic ash is di v i ded into three aspects: avoidanc e , rec o g n i t i on, and proc e du re s . The fol l o w i n g information is general; flight crews should refer to their respective company’s operating manuals for details.

Avoidance. ■ Pressurization. Cabin pressure can Preventing flight into potential ash change, including possible loss of environments requires planning in cabin pressurization. these areas: ■ Static discharges. A phenomenon engine stall margins by increasing ■ Dispatch needs to provide flight similar to St. Elmo’s fire or glow the flow of bleed air. crews with information about vol- can occur. In these instances, 5. If possible, start the auxiliary canic events, such as potentially blue-colored sparks can appear to power unit (APU). The APU can eruptive volcanoes and known ash flow up the outside of the wind- power systems in the event of a s ig ht i ng s, that could affect a shield or a white glow can appear multiple-engine power loss. It can p a rticular route (see sidebar at at the leading edges of the wings also be used to restart engines bottom of p. 26). or at the fron t of the engi n e inlets. through the use of APU bleed air. ■ Dispatch also needs to identify Procedures. 6. If volcanic dust fills the flight alternate routes to help flight The following nine procedures are gen- deck, the crew may need to use crews avoid airspace containing eral recommendations. Each operator’s oxygen. Use flight deck oxygen at volcanic ash. flight operations manuals will include the 100 percent setting. Manual ■ Flight crews should stay upwind of more specific directions. dep l o y me n t of the passenger oxy ge n volcanic ash and dust. 1. Reduce thrust to idle immediately. system is not required because it will deploy automatically if the ■ Flight crews should note that air- By red uci n g t h r u s t ,e ng i ne s may su f - cabin altitude exceeds 14,000 ft. borne weather radar is ineffective fer less buildup of molten debris on for distinguishing ash and small turbi n e blades and hot - s e c t i on com- 7. Turn on the continuous ignition. dust particles. po ne nt s .Idl e th r u s t a l l o w se ng i nes to Confirm that autostart is on, if continue producing electrical power, Recognition. available. In the event that the bleed air for pressurization, and engines flame out or stall, use Indicators that an airplane is pene- hyd rau l i c power for airplane contro l . ap p ro p r i ate proc e du r es to restart the trating volcanic ash are related to eng i ne s . During restart, the engi ne s odo r , haze, changi n g engi n e condi t io n s, 2. Turn the autothrottles off. This may take longer than normal to airspeed, pressurization, and static pre v e n ts the engi n es from incre a s i n g reach idle thrust due to the com- discharges. thrust above idl e . Ash debris in the eng i n e can result in red uced surge bined effects of high altitude and ■ Odor. W hen enc o u nt e r i ng a vol- marg i n s, and limiting the number of vo l c a n i c ash inges t i on. If an engi n e c a n ic ash cloud, flig ht crews usu- thrust adjustments improves the fails to start, try restarting it again ally no t ice a smoky or acrid odo r chances of engine recovery. immediately. Flight crews should that can smell like electric a l remember that the airplane may be s mo ke, burned dust, or sulfur. 3. Exit the ash cloud as quickly as possible. A 180-deg turn out of the out of the airstart envelope if the ■ Haze. Most flight crews, as well as ash cloud using a descending turn encounter occurs during cruise. cabin crew or passengers, see a is the quickest exit strategy. Many 8. Monitor engine exhaust gas haze develop within the airplane. ash clouds extend for hundreds of temperature (EGT). Because of Dust can settle on surfaces. miles, so assuming that the potential engine debris buildup, ■ Changing engine conditions. encounter will end shortly can be the EGT can climb excessively. Surging, torching from the false. Climbing out of the ash could The flight crew should prevent EGT tailpipe, a nd flameouts can occur. result in increased engine debris exceedances. Shut down the engine E ng i ne te m p e ra t u r es can change buildup as the result of increased an d restart it if the EGT is approa c h - un exp e c t e d l y , and a white glow temperatures. The increased engine in g limits similar to a hung start. can appear at the engine inlet. buildup can cause total thrust loss. 9. Fly the airplane by monitoring ■ Airspeed. If volcanic ash fouls the 4. Turn on engine and wing anti-ice a i rspeed and pitch attitude. pitot tube, the indicated airspeed devices and all air-conditioning If necessary, follow the procedure can dec r ease or fluct u ate errat ic a l l y . packs. These actions improve the for flight with unreliable airspeed.

A E R O 23 S U M M A RY Though the number of commercial airplane encounters with volcanic ash clouds has decreased significantly over the past several years, the potential for this type of event still exists. Efforts to advance knowledge about how to avoid and recover from these encounters have resulted in improved capa- bility in these areas. By working with members of the volcanol o g ic a l community, the aviation industry has developed procedures to share information about events with flight crews, dispatchers, volcano scientists, and others. Volcano observatories that provide daily updates through e-mail messages or phone recordings have been established. In addition, a variety of Internet sources provide infor- mation that operators can tailor to their specific flight domains. Fi na l l y , fligh t operat io n s proc e du re s are documented and available to flight crews to help them respond immediately and appropriately to maintain the highest possible level of flight safety.

A E R O 24 ALASKA AIRLINES PROCEDURES FOR OPERATING IN VOLCANIC ASH CONDITIONS

la s k a Airlines has man y active volcanoes within its fligh t dom ain. To prep a r e for an eruption and res u l t - in g enco u n ter with volcanic ash, the airline has developed focused guidel i n es for fligh t operat io n s whe n A er u p t io n s inte r f e r e with its route struct u re s : 1. When in doubt, don’t fly. 2. Use facts and data. 3. Iden tify the location of both the ash and clear area s . 4. Stay focused.

IDENTIFY THE LOCATION OF BOTH WHEN IN DOUBT, DON’T FLY 1 3 THE ASH AND CLEAR AREAS

The fundamental principle by which Alaska Airlines Al a s k a Airlines tr acks the ash by asking a num b e r of operates is knowing where to find the ash after a vol- qu e s t io n s: canic eruption. If unsure of the ash location, it will ■ Where is the ash itself? not allow its flight crews to fly through the eruption ■ area. Though this approach is conservative, Alaska Where is the volcanic source of the ash? Ai r l i n es successfully and safely operated after the 1989 ■ What are the winds doing? Mt. Redoubt eruption and other volcanic eruptions. ■ What information is available from the volcanological community? USE FACTS AND DATA 2 ■ What information do the reports from the pilots, selected contacts, and others contain? Alaska Airlines has selected several information sources, uses Volcanic Ash Advisory Statements from Al a s k a Airlines then prov i des its pilots with infor m a- the Volcanic Ash Advisory Centers, and is in direct ti on on where to fly and the reasons for not flying in communication with the Alaska Volcano Observatory. certain areas. During a major eruption, Alaska Airlines will interview its own pilots as well as other operators’ pilots about 4 STAY FOCUSED their observations on ash location. It has also estab- lished contacts on the ground that it can call for Ed Haeseker, manager of air traffic control for Alaska add i t io n al inte l l i genc e . These indi v i duals incl u de may o r s Airlines, worked during the Mt. Redoubt event with and police officers in vil- Tom Cufley, then chief pilot at Alaska Airlines. They lages and towns near the found that a small team worked better than a large airline’s flight paths. If team, especially if the chief pilot prov i ded infor ma t io n Alaska Airlines receives d i rectly to the flig ht crew in the early days of the i nc o ns i s t e nt info r ma t io n , e v e nt. In add i t ion, a small team can travel mo re it do u b l e - c hecks and con- q u ickly to the site whe re the greatest assistance is ti n ual l y validates what nee d ed and rem ain focused on the key task: ident i f y i n g appears to be correct. where the ash is.

A E R O 25 ICAO ACTIVITIES ON VOLCANIC ASH The International Civil Aviation Organization (ICAO) in i t i ated a volcanic ash effort in 1982 after mul t i p l e volcanic ash encounters by 747 airplanes near Jakarta, Indonesia. The resulting organization, the Volcanic Ash Warnings Study Group, has worked since then to standardize the information provided to flight crews about volcanic eruptions. In addition, ICAO formed the International Airways Volcano Watch (IAVW) in 1987. This effort formalized the international arrangements for monitoring and providing warnings to airplanes about volcanic ash in the atmosphere. ICAO annex III and the World Meteorological Organization (WMO) Technical Regulation C.3.1 introduced a requirement to disseminate information about volcanic ash to airplanes in the form of signifi- cant meteorological information (SIGMET) and notice to airmen (NOTAM). T he first WMO / IC AO workshop on volcanic ash hazards was held in Darwin, Au s t ra l ia, in 1995. Since then, a number of the T. Fox designated Volcanic Ash Advisory Centers (VAAC) have come S e c re t a ry of the ICAO Volcanic Ash into full operation. A second workshop in Toulouse, France, in Wa rnings Study Gro u p 1998 focused primarily on VAA C res p o ns i b i l i t i es and proc e du r es Chief - Meteorology More information about ICAO activities related to v o l c a n ic ash I n t e rnational Civil Av i a t i o n a v o ida nce and enc o u nters is available in the organization’s O rg a n i z a t i o n document titled “Operational Procedures And List Of 999 University Stre e t Operational Contact Points Between Vulcanological Agencies, Meteorological Watch Offices And Area Cont rol Centre s ,” or M o n t real, Quebec H3C 5H7 Canada f rom the address to the rig ht. E-mail: [email protected]

VO LC A NO E R U P T I O N Eruption warnings are issued in the form of color-coded information releases. Over the past 10 years, this method has proved to be effec- WARNING COLOR CODES tive for alerting the aviation community to potential volcanic ash.

A L E RT COLOR CODE VOLCANO ACTIVITY STAT U S R e d Volcanic eruption in pro g ress. Ash plume or cloud re p o rted above FL 250. Volcano dangerous, eruption likely, with ash plume or cloud expected to rise above FL 250. O r a n g e Volcanic eruption in pro g ress but ash plume or cloud not reaching nor expected to reach FL 250. Volcano dangerous, eruption likely, but ash plume or cloud not expected to reach FL 250. Yellow Volcano known to be active from time to time and volcanic activity has recently i n c reased significantly, volcano not currently considered dangerous but caution should be exerc i s e d . After an eruption, i.e., change in alert to yellow from red or orange, volcanic activity has decreased significantly, volcano not currently considered dangerous but caution should be exerc i s e d . G re e n Volcanic activity considered to have ceased and volcano re v e rted to its normal state.

T he re s p o nsible volcano l o g ical age ncy in the re g ion whe re the volcano erupts should pro v ide the are a c o ntrol center with (1) the color code for the level of alert indicating the status of activity of the volcano a nd (2) any change from a pre v ious status of activity (e. g . , “Red alert fo l l o w i ng yellow” or “Green alert fo llowing orange”). Source: ICAO—International Airways Volcano Watch.

A E R O 26 VOLCANIC ASH RESOURCES Vol c a n i c ash res o u r ces are available worldwide and in many forms accessible to operators. Volcano observatories are located throughout the world, including the Alaska Volcano Observatory for information about North Pacific volcanoes and the Nordic Volcanological Institute for informa- t ion about volcanic activity that could affect North At l a nt ic ro u t e s. Ma ny of these observatories provide immediate eruption and volcanic ash updates to operators by fax, e-mail, telephone, or teletype. Information is also available on the World Wide Web at the following sites: The Smithsonian National Museum of Natural History Global Vo l c a n i s m P ro g r a m : http://www.volcano.si.edu/gvp/ The U.S. Geological Survey: http://www.usgs.gov/themes/volcano.html The Airline Dispatcher Federation (a detailed paper about volcanic ash written by Leonard J. Salinas of United Airlines, Chicago, Illinois): http://www.dispatcher.org/library/VolcanicAsh.htm The Committee on Earth Observation Satellites Disaster Management S u p p o rt Pro j e c t / Volcanic Hazards Management (an eff o rt by the U.S. National Oceanic and Atmospheric Administration; information on track- ing ash clouds): The Istituto Internazionale di Vulcanologia (a summary of volcanoes in I t a l y ) : http://www.iiv.ct.cnr.it/ The Nordic Volcanological Institute (information about volcanoes in and a round Iceland): http://www.norvol.hi.is/index.html The Volcanological Society of Japan (eruption information, live images of Japanese volcanoes, and other information): http://hakone.eri.u-tokyo.ac.jp/kazan/VSJ1E.html C u rrent Eruptions in Japan (additional current information): http://hakone.eri.u-tokyo.ac.jp/vrc/erup/erup.html Other sources of information include the following: The Boeing Company, A i r l i n e r magazine (“Vulcan’s Blast,” April-June 1990, and “Vulcan Returns: Volcanic Ash Effects on Airplanes Revisited,” October- December 1991) and video (“Vol c a n i c Ash Avo i dan ce: Fligh t Crew Brief i ng ” ) . U.S. Federal Aviation Administration, Aviation Safety Journal reprint (“The Volcano Threat to Aviation Safety”). Casadevall, T. J., ed. 1994. The First International Symposium on Volcanic Ash and Aviation Safety: Proceedings Volume: U.S. Geological Survey Bulletin 2047. Casadevall, T. J., T. B. Thompson, and T. Fox. 1999. World map of volcanoes a nd principal air na v ig a t ion feature s. U.S. G e o l o g ical Survey Map I-2700.

THE PRIMARY SOURCE FOR ANY VOLCANIC ERUPTION AND ASH INFORMATION IS A VOLCANIC ASH ADVISORY CENTER. THE OTHER SOURCES LISTED HERE MAY OFFER MORE DETAILED INFORMATION ON A PARTICULAR ERUPTION. – ED.

A E R O 27