Volcanic Hazards and Aviation Safety: Lessons of the Past ...

FLIGHT SAFETY FOUNDATION • FLIGHT SAFETY DIGEST • MAY 1993 1

Volcanic Hazards and Aviation Safety:Lessons of the Past Decade

Avoiding the ash-laden cloud from a volcano isthe only way to guarantee that an aircraft is not damagedby the cloud’s dangerous particles, which can destroy an

aircraft engine and threaten flight safety.Nature remains the ultimate force.

Thomas J. CasadevallProject Chief, Volcanic Hazards and Aviation Safety

U.S. Geological Survey

Modern jet airplanes and their engines are de-signed to operate in environments that are freefrom dust and corrosive gases.

Explosive volcanic eruptions, such as the 1991eruptions of Mount Pinatubo Volcano in thePhilippines, inject large amounts of very smallrock fragments, known as volcanic ash, andcorrosive gases into the upper troposphere andlower stratosphere. Unfortunately, this is alsothe normal cruising altitude for jet airplane traffic.

Such explosive eruptions have occurred some-where on earth about 10 times per year duringthe past decade.6 Many of these explosive volca-noes occur around the Pacific “ring of fire” andhave a direct impact on air routes around thePacific basin. [The ring of fire refers to the chainof volcanoes located northward from Panamaalong the western coast of the United States,westward across the Aleutian Islands, south-ward along the various island chains borderingthe Asian coast, through the islands in Malaysiaand then eastward back into the Pacific Ocean.]

In the past 12 years, more than 60 modern jetairplanes, mostly jumbo jets, have been dam-

aged by drifting clouds of volcanic ash that havecontaminated air routes and airport facilities.Seven of these encounters are known to havecaused in-flight loss of engine power to jumbojets carrying a total of more than 2,000 passen-gers. The repair and replacement costs associ-ated with airplane-ash cloud encounters are alsohigh. The repair of the Boeing 747-400 damagedby an ash cloud from Redoubt Volcano, Alaska,U.S., in December 1989 was estimated to cost inexcess of US$80 million.12 Compounding the prob-lem is the fact that volcanic ash clouds are notdetectable by the present generation of radarinstrumentation aboard aircraft. Complete avoid-ance of volcanic ash clouds is the only proce-dure that guarantees flight safety.

Ash Cloud EncountersIn Early 1980s Spurred Study

Of Safety Issues

The threat of volcanic hazards to aviation safetyfirst received public attention when severalcommercial jet aircraft were damaged afterflying through volcanic ash clouds from the

FLIGHT SAFETY FOUNDATION • FLIGHT SAFETY DIGEST • MAY 19932

May 1980 eruptions of Mount St. Helens inWashington, U.S. Interest in the aviation safetyissue grew rapidly in the early 1980s afterseveral jumbo jets encountered ash clouds thathad traveled several hundred miles from theirsources. Eruptions of Galunggung Volcano inIndonesia in 1982, Redoubt Volcano in Alaska,U.S., in 1989 and 1990, and Mount PinatuboVolcano in 1991 caused significant damage toaircraft, including engine failures, and severelydisrupted regional air operations. Ash cloudsfrom eruptions in Colombia, Italy, Japan, theUnited States and Zaire have also damagedaircraft.

Ash Clouds Vary inType and Severity

Active volcanoes emit several types of plumesand clouds. Quiescent plumes consist of wa-ter vapor and gases with few or no rock par-ticles. They seldom rise above 20,000 feet (6,060meters) and usually disperse within tens ofmiles of the volcano. Quiescent plumes arenot a significant threat to aviation safety.

Eruption columns are the violent,cauliflower-shaped pillars of ashand gas generated above a volca-nic vent during an explosive erup-tion. Within tens of minutes somecolumns can rise to altitudes of40,000 feet (12,121 meters) to100,000 feet (30,303 meters). Theytypically contain blocks of volca-nic rock up to several inches indiameter, plus dense concentra-tions of ash and gas. Eruption columns sel-dom last for more than a few hours and onlyaffect an area within a few miles of the volca-nic vent, so they pose a relatively small threatto aviation safety. However, because eruptioncolumns contain large blocks of rock, they mustbe avoided by aircraft.

Drifting ash clouds consist of finely brokenrock fragments and gas that are carried awayby winds from a violent eruption column. Largevolcanic eruptions produce clouds that enterthe stratosphere and may be carried by the

jetstream for thousands of miles. Althoughthese ash clouds can circle the globe in a mat-ter of weeks, they usually deposit most oftheir ash within a few hours to a few days.Drifting ash clouds pose the greatest threat toaircraft.

Mitigating the ash hazard is complex becauseash clouds are difficult to detect by conven-tional weather radar or visually from an air-plane. Ash clouds are very difficult to detect atnight, and they may be obscured by weatherclouds. Ash clouds must be tracked by relyingon volcanological observers on the ground, pi-lot reports (PIREPS), satellite observations andmeteorological forecasts of ash-cloud movements.Immediate communication from ground observ-ers and meteorologists to aircraft dispatchersand controllers, and to pilots, is essential.

Three Eruptions AffectedAircraft Operations Significantly

Three eruptions of the past decade have greatlyhelped to focus attention on the problem ofvolcanic hazards and aviation safety. Each of

these eruptions included multipleencounters between aircraft anddrifting volcanic ash clouds.

In 1982, two Boeing 747-200 pas-senger jets encountered ash at nightf rom separa te e rupt ions o fGalunggung Volcano in Java, In-donesia.11 In each case, pilots ob-served St. Elmo’s fire, noted theacrid smell of sulfur gas, observed

fine dust quickly filling the cabin and experi-enced moderate turbulence while in the ashcloud.14 In both cases, volcanic ash entered thejets’ engines and caused surging, flameout andimmediate thrust loss of all four engines. Af-ter powerless descents of nearly 25,000 feet,the pilots of both aircraft eventually restartedall engines and landed safely at Jakarta. Bothaircraft suffered extensive damage to enginesand exterior surfaces.

The December 1989 to April 1990 eruptionperiod of Redoubt Volcano widely affected

Drifting ashclouds pose the

greatest threat toaircraft.


commercial and military airplane operationsnear Anchorage.4 These affects included re-routing and cancellation of flight operationsfor some time, which significantly affectedthe Anchorage economy.

From December through February, ash cloudsfrom Redoubt damaged five commercial jetliners. The most serious incident occurred onDecember 15, 1989, when a new Boeing747-400 encountered a drifting ash cloud whiledescending to land at Anchorage. On enteringthe cloud at 25,000 feet (7,576 meters), about150 miles (242 kilometers) northeast ofRedoubt, the pilot tried to fly out ofthe ash cloud and had climbed nearly3,000 feet (909 meters) before all fourengines failed. The aircraft descended13,000 feet (3,939 meters) without powerbefore the engines were restarted andflight resumed to Anchorage. No pas-sengers were injured, but the aircraft’sengines, avionics and exterior were dam-aged extensively. Repair costs were es-timated to exceed $80 million.12

Other damaging encounters betweenjet aircraft and ash clouds from Redoubtwere reported on December 15 and 16,1989, and February 21, 1990. Fortunately,these aircraft did not experience en-gine failures. Following the eruptionsand encounters on December 15 and16, Anchorage International Airport re-mained open. Most air carriers, how-ever, canceled operations for up to severaldays, and some international carrierscanceled or curtailed operations through January1990. These curtailments reduced revenues atAnchorage International Airport by approxi-mately $2.6 million.3

The June 15, 1991, eruption of Mount Pinatubowas the largest of the past 60 years.7 The erup-tion produced a huge ash cloud that movedrapidly to the west over the South China Sea,Borneo and Indochina Peninsula (Figure 1),disrupting aircraft operations over a broad areaof the Philippines and Southeast Asia. Fiveairports in the Philippines, including ManilaInternational Airport and military airfields atBasa, Clark, Sangley and Cubi Point, were dam-

aged by ashfall, which occurred during amajor typhoon and covered airfields at Basa,Clark and Cubi Point with up to six inches ofash. The wet ash and constant ground shakingon June 15 led to the collapse of numerousaircraft hangars and maintenance facilities atseveral airfields. Manila International Airportwas closed from June 15 to 19 and did notresume normal operations until July 4. Clarkand Basa remain closed.

At least 20 commercial jet airplanes were dam-aged by volcanic ash. Most damage was be-

cause of in-flight encounters with ash cloudsfrom Pinatubo. These in-flight encounters in-volved 10 Boeing 747s, five DC-10s, one L-1011, and one Boeing 737. Because of ash in-gestion, a total of 10 engines, including fourengines on a single Boeing 747, were badlydamaged and had to be replaced. Several otherairplanes were damaged on the ground by ashloading and improper removal of ash fromcockpit windows.

Unlike encounters at Galunggung and Redoubt,which caused multiple engine failures andoccurred within 150 miles (242 kilometers) ofthe erupting volcano, the majority of Pinatubo

Figure 1

0609

12

15

1821

00

0306

09

130E120110100

10

20N

Heavy Lines = 3-hour Intervals

Development of the Pinatubo Ash Cloud,June 15-16, 1991

Source: Tanaka and Hamada, 199113


encounters were at distances of more than600 miles (967 kilometers) from Pinatubo. Onlytwo encounters occurred during landing ap-proaches to Manila. All other encounters wereto the west in the Singapore, Ho Chi Minh andHong Kong Flight Information Regions. Thislarge number of encounters reflected a majorbreakdown in the ways that information aboutthe ash-cloud hazard was communicated. Inthe Philippines, volcanologists of the PinatuboVolcano Observatory were aware of the erup-tions at the time they occurred. With access toreal-time satellite information, meteorologistsand volcanologists in the United States werealso aware of the volcano’s activity, includingthe speed and direction of the ash cloud’s move-ment. The key problem was one of timely com-munication of this information to the properagencies in the aviation community.

Aircraft Damage Can beImmediate and Long-term

A range of damage may occur to an airplanethat has flown through a volcanic ash cloud(Figure 2). Effects may be apparent immedi-ately or they may take longer to manifest them-selves. Immediate effects are easy to identify

and, in some cases, easily repaired. Medium-term and long-term effects are considerably moredifficult to identify and are primarily related tothe gaseous components in the volcanic cloud,especially the acid gas sulfur dioxide.

When a modern jet aircraft, traveling at highspeed, encounters a drifting cloud of sand-sizerock fragments, a wide variety of damage willoccur and the consequences are usually evi-dent immediately. Volcanic ash is typically com-posed of a mixture of sharp, angular fragmentsof rapidly quenched volcanic glass, as well asmineral and rock fragments that range in sizefrom fine powder to fragments up to an eighthof an inch in diameter. Fragments typically in-clude the minerals feldspar, quartz and pyrox-ene. The ash is hard and can easily scratch andabrade glass, plastic and metals. Any forward-facing surface of the airplane, such as win-dows, landing light covers, leading edges ofthe wings and the fuselage, will be damaged(Figure 2). Because of its small size, ash alsocan enter very small openings in the aircraftexterior, including the air supplies for flightinstruments such as the pitot static system.

The ingestion of volcanic ash by jet engines maycause serious deterioration of engine performanceor even engine failure (Figure 3). Since 1980, at

COCKPIT, MEC COMPONENTCHECK

¥ L/E AREA EROSION¥ FLAP FIXED FAIRING

PAINT EROSION

¥ WING NAV L T COVEREROSION

¥ ALL PSU R/L T AREA DIRTY¥ ALL STOWAGE BIN UPPER DIRTY

¥ L/E AREA EROSION

¥ ALL ENG FAN BLADE, TURBINE SLEEVE INSIDE¥ ALL ENG 1ST T/NGV COOLING HOLE 70-80% CLOG

¥ LDG L T INNERL T COVER CRAZING

¥ AUX-2 PITOT, P/S PROBE

¥ L-2, R-3 WINDOW¥ CBN WINDOW

MINORSCRATCH

Source: Thomas J. Casadevall

Figure 2Diagram of Boeing 747-400 Aircraft Showing Exterior Damage from Ash Cloud


least seven encounters between jet-powered air-craft and volcanic ash clouds have resulted intemporary engine failures. Two processes dete-riorate engine performance: erosion of movingengine parts, such as compressor and turbineblades, and accumulation of partially melted ashin hot zones in the engine. Erosion of compres-sor blades reduces the compression efficiency ofthe engine but has not been proven to causeengine failure. Ash deposits in the hot sectionsof the engines, including the fuel nozzles, thecombustor and the turbine, reduce the efficiencyof fuel mixing and restrict air passing throughthe engine. This causes surging, flame-out and immediate loss of engine thrust.This loss is the principal cause of enginefailure.

Air that enters the airplane cabin is takenfrom the engine. This air powers gen-erators and pneumatic systems through-out the aircraft and provides breathingair for passengers. The air passes throughan environmental control system andis carried through ducts to appropriateparts of the aircraft.

Ash particles may abrade completelythrough the duct system as well as clogfilter systems designed to remove mois-ture from the air.

Flying an airplane through an ash cloudcauses damage that is immediately evi-dent. More difficult to evaluate is thedamage that occurs by repeated long-term exposure to the clouds of mostlygas and gas-derived particles that remain inthe stratosphere. For large eruptions, such asMexico’s El Chichon in 1982, and Pinatubo in1991, these gases may remain suspended inthe stratosphere for years after the solid rockparticles have settled. The sulfur dioxide inthe clouds absorbs water vapor and is con-verted to droplets of sulfuric acid. When air-craft fly in a stratosphere polluted with volca-nic aerosols, these acid droplets adhere to aircraftskins and windows and may penetratemicrocracks in those surfaces. This is most easilyobserved in acrylic windows where the cloud-ing and crazing of acid-attacked windowsprompts their replacement.8,9,1

Other corrosion damage to plastics and rub-ber used in seals and lubricants and metalcomponents used in the airframe is not aseasily identified. Identifying corrosion dam-age to these components may require long-term programs of inspection and maintenance.Even then, corrosion by volcanic pollution maybe impossible to distinguish from other envi-ronmental pollution such as salt in sea sprayand acid gases in polluted urban atmosphere.

Because engines are typically inspected andrebuilt more frequently than the rest of theairplane, the problems of engine corrosion by

volcanic gas may be more easily identifiedand addressed during regular maintenance.

Nevertheless, the airframe and skin are mostsusceptible to long-term influence from repeatedexposure to volcanic clouds. Scientists and engi-neers have not yet assessed the long-term effectof corrosion by acid components in volcanic clouds.

Aircraft Also FaceOn-ground Ash Hazards

It is easy to appreciate the nature of damagethat occurs during an in-flight encounter with

COMBUSTOR

Jet Engine Cutaway ShowingAreas of Damage by Ash Cloud

Source: Thomas J. Casadevall

Figure 3

-


an ash cloud. However, a host of additionalproblems face an airplane sitting or taxiing onthe ground. For example, ashfall of more thanseveral inches will place a considerable loadon an aircraft, especially if the ash falls wetwith rain. Some aircraft may respond to load-ing by settling back on their tail sections. Ashloading also may cause hangars to collapse,especially if ash falls wet and if ground shak-ing caused by volcanic earthquakes is strongand prolonged, as it was duringthe Pinatubo eruption.

Ash covering airport runways andtaxiways is easily resuspended fordays to weeks by wind and byground movement of aircraft fortakeoffs, landings and taxiing. In-gestion of resuspended ash by jetengines, especially during full-power takeoff, may be just as dam-aging as ash encountered while inflight. When wet, ash becomes slip-pery because of its fine grain size. Slipperyash reduces the coefficient of friction betweentires and the runway surface, thus affectingthe braking and turning performance of air-craft.

Removing ash from an airplane and its en-gines must be done with care. Simply washingfine ash from an airplane’s exterior must beavoided because water added to ash producesa slurry that may penetrate openings in theskin surface. Subsequent removal is costly andmay require disassembling the airplane. A simplethree-step procedure is recommended for re-moving ash from the surface of an airplaneparked on the ground: (1) sweep ash awaywith a broom; (2) vacuum remaining ash withan industrial vacuum; and (3) wash away re-maining fine ash, being careful to wash awayfrom openings in the airplane surface.

Only a few airports have had to deal withvolcanic ashfall. One facility where carriersand managers have experience is KagoshimaAirport in Japan, which receives frequent ashfallfrom nearby Sakurajima Volcano. While thereare some common elements in the cleanup ef-forts at each airport, airport managers andground crews have typically relied on local

solutions for their cleanup efforts. The type ofcleanup effort will usually depend on the amountof ashfall.

Ashfalls less than 0.25 inch (6.2 millimeters)can usually be handled by thoroughly wash-ing airport surfaces, if adequate water anddrainage capacity is available. For thicker ashfalls,initial washing is discouraged because ash islikely to fill and block drainage lines. Instead,

experience shows that accumulat-ing the ash into mounds largee n o u g h t o r e m o v e w i t hearthmoving equipment is the bestfirst step. This may be followedby washing. If ash is moved to theedges of runways and taxiways, itshould be removed or stabilizedwith quick-growing grass or emul-sified asphalt to avoid resuspensionof ash by aircraft movement orwind. This method was used suc-cessfully at Manila International

Airport and Cubi Point Naval Air Station af-ter the 1991 eruptions of Pinatubo.

Research and Experience HaveYielded Valuable Lessons

At considerable expense during the past de-cade, some important lessons have been learnedabout the threats that volcanic ash poses toaviation safety in the air or on the ground. Anaircraft cannot fly through an ash cloud with-out sustaining some damage. Avoiding an ashcloud is the only way to guarantee that anaircraft is not damaged.

As existing instruments aboard aircraft sim-ply cannot detect or locate an ash cloud, themost important lesson is that immediate com-munication to a pilot about a potential volca-nic threat is essential to successful avoidance.Three essential sources of information aboutvolcanic activity and ash clouds include ob-servations from ground-based observers to alertand verify an eruption; from pilots, throughpilot reports about eruptive activity and ashclouds; and from satellite observations to de-tect and track ash clouds.

Avoiding anash cloud is the

only way toguarantee thatan aircraft isnot damaged.


No single source of information is completelyreliable and feedback between these three sourcesis essential for complete and accurate commu-nication. National and international organiza-tions have initiated efforts to improve commu-nications between volcanologists, meteorologists,air traffic controllers and pilots. Yet, the im-provements cannot substitute for increased pi-lot awareness about what to do when an ashcloud is entered inadvertently.

Aircraft must avoid flying into volcanic ashclouds. Avoiding an ash cloud may be diffi-cult or even impossible for an airplane in flight,especially at night. Although such an encoun-ter will almost surely result in somedamage to the airplane, depend-ing on the ash content of the cloudand the duration of the encounter,the aircrew can minimize the damageby reducing engine power and re-versing course to escape the ashcloud. Such actions require thatpilots be well informed about thenature of ash clouds and that theybe trained in procedures to mini-mize damage.

If the aircraft experiences enginefailure, pilots must be aware thatengine parameters such as tempera-ture and turbine speed for enginestarts at high altitude differ fromnormal starts made on the ground.Analysis of incidents where enginesfailed because of ash ingestion in-dicates that in some cases initialrestart attempts would probablyhave been adequate had pilots beenaware of the characteristics of high-altitude engine restarts.

For aircraft on the ground or en route towarda potentially hazardous ash cloud, communi-cations between controllers, dispatchers andpilots can usually lead to successful avoid-ance. This will typically mean carryingadditional fuel or planning alternate routes toavoid the contaminated airspace.

The United States has 56 volcanoes that haveerupted during the past 200 years. Forty-four

of these volcanoes are located in Alaska,including 30 in the 1,000-mile-long (1,613 kilo-meters) Aleutian Island chain. The U.S. Geo-logical Survey (USGS) is responsible for as-sessing volcanic hazards and monitoring restlessvolcanoes in the United States.15 Only 19 ofthe 56 U.S. volcanoes are monitored by theUSGS from volcano observatories located inHawaii, Washington and Alaska. Presently, onlyone of the 30 historically active Aleutian Is-land volcanoes is monitored. This gap in moni-toring coverage is especially critical in view ofthe large number of commercial and militaryaircraft that use the great circle routes.

While the USGS efforts focus onground-based studies, the U.S.National Oceanic and AtmosphericAdministration (NOAA) and theU.S. Federal Aviation Administra-tion (FAA) monitor and track vol-canic ash clouds in the United Stateswith satellite imagery and pilotreports. In 1989, NOAA and theFAA initiated a joint effort to trackvolcanic ash clouds and to warnpi lo ts v ia not ices to a i rmen(NOTAMs). Based on experiencegained from the 1989 to l990 Re-doubt eruptions and the l991Pinatubo eruption, the NOAA-FAAeffort will also formally link theUSGS into the process of inform-ing pilots about the threat of vol-canic ash clouds.

In cooperation with the Interna-tional Civil Aviation Organization(ICAO) and the Air Line Pilots As-sociation (ALPA), the USGS con-tinues to seek ways to inform andeducate the aviation community

about volcanic hazards and what steps can betaken to mitigate and minimize an ash-air-plane encounter — in the air and on the ground— in ways that promote the safety of air travel.

The growing number of ash encounters dur-ing the past decade has prompted several in-ternational efforts to evaluate and address theproblem of volcanic hazards to aviation safety.In 1982, a Volcanic Ash Warnings group was

If the aircraftexperiences

engine failure,pilots must be

aware thatengine

parameters suchas temperature

and turbine speedfor engine startsat high altitude

differ fromnormal startsmade on the

ground.


organized under leadership of ICAO. Also in1982, the Australian Department of Aviationcreated an Airways Volcano Watch.

A May 1985 encounter between a Boeing747-200 and an ash cloud from Soputan Volcanoin Sulawesi, Indonesia, prompted the Indone-sian and Australian governments to form a liai-son committee to improve communications aboutvolcanic eruptions in the Indonesian region.

In 1988, ICAO member states adopted amend-ments for an International Airways VolcanoWatch to provide alerts about eruptive activ-ity worldwide. These efforts included devel-opment of a special form for pilots to reportvolcanic events.5

Communicating past experiences and practi-cal solutions to pilots and the airlines is key tosolving the ash-aircraft problem. The effortsof a wide variety of agencies, both public andprivate, led to the First International Sympo-sium on Volcanic Ash and Aviation Safety, heldin Seattle, Washington, U.S., in July 1991.4 Thesymposium sought to encourage improvementsin the detection, tracking and warning of vol-canic ash hazard so that aircraft may avoidash clouds; and to review the effects of volca-nic ash on aircraft so that pilots who encoun-ter ash might respond appropriately. More than200 participants from 23 countries attendedthe symposium.

The manufacturers’ principal trade associa-tion, the Aerospace Industries Associationof America (AIAA), formed a Volcanic AshStudy Committee in February 1991 and pre-sented its recommendations at the interna-tional symposium. In connection with theSeattle symposium, ALPA, the Air TransportAssociation of America (ATA) and the FlightSafety Foundation have actively communi-cated about the volcanic ash problem to theirmembers and constituents, both nationallyand internationally.

Volcanic Ash Threat WillRemain in Coming Years

During the past decade, we have learned somehard lessons about the threat that volcanic ash

presents to the modern jet airplane and itsengines. This threat is not likely to disappearin coming years. The best solution to the prob-lem is to avoid areas contaminated by ash.Avoidance requires the coordinated efforts ofa broad group of technical specialists includ-ing volcanologists, meteorologists, dispatch-ers, pilots and controllers, all working togetherto detect and track volcanic ash clouds andto provide warnings about volcanic hazardsto aviation safety. The goal of these efforts isto avoid an area or airspace that has beencontaminated by volcanic ash and corrosivevolcanic gas.

Changes to the technical design of airplanesand powerplants have been considered andrejected as being too costly or impractical. De-velopment, particularly in Australia, of sen-sors carried on the airplane is in the earlystages and is a future hope to assist pilots toavoid ash clouds, especially for air routes overremote regions where volcanoes are largelyunmonitored.

Because ash clouds often drift over nationalboundaries and between flight informationregions, regional air traffic facilities and carri-ers must be informed about potential volcanicthreats, not just in their local flight region, butin adjacent regions as well. The hazards posedby volcanic clouds have a global scope thatrequires both local and global approaches toensure a successful solution. �

References

1. Bernard, A. and W.I. Rose, Jr., “The Injec-tion of Sulfuric Acid Aerosols in the Strato-sphere by El Chichon Volcano and Its Re-lated Hazards to the International AirTraffic.” Natural Hazards, v. 3, 1990.

2. Blong, R. J., Volcanic Hazards, A Source Book onthe Effects of Eruptions, Academic Press, 1984, p.424.

3. Brantley, S.R. (ed.), “The Eruption of Re-doubt Volcano, Alaska December 14, 1989-August 31, 1990”: U.S. Geological SurveyCircular 1061, 1990. Casadevall, T. J. (ed.),


The First International Symposium on Vol-canic Ash and Aviation Safety, Programsand Abstracts: U.S. Geological Survey Cir-cular 1065, 1991.

4. Casadevall, T.J., in press. “The 1989-1990Eruptions of Redoubt Volcano, Alaska; Im-pacts on Aircraft Operations,” Journal ofVolcanology and Geothermal Research.

5. Fox, T., “Global Airways Volcano WatchIs Steadily Expanding,” ICAO Bulletin,April 1988.

6. McClelland, L., T. Simkin, M. Summers, E.Nielsen, and T.C. Stein, Global Volcanism1975-1985. Prentice-Hall Inc., 1989.

7. PVOT (Pinatubo Volcano Observatory Team),“Lessons from a Major Eruption: Mt.Pinatubo, Philippines,” Eos, v. 72, 1991.

8. Rogers, J.T., “Results of El Chichon: Pre-mature Acrylic Window Crazing.” BoeingAirliner April-June 1984.

9. Rogers, J.T., “Results of El Chichon—PartII.: Premature Acrylic Window Crazing StatusReport.” Boeing Airliner April-June 1985.

10. Rose, W.I., “Interaction of Aircraft and Ex-plosive Eruption Clouds: A Volcanologist’sPerspective.” Aerospace Industries Associa-tion of America Journal, v. 25, 1987.

11. Smith, W. S., “High-altitude Conk Out,”Natural History, v. 92, no. 11, 1983.

12. Steenblik, J.W., “Volcanic Ash: A Rain ofTerra.” Air Line Pilot, June/July 1990.

13. Tanaka, M. and N. Hamada, “The EruptionCloud of Mt. Pinatubo Observed by Geo-stationary Meteorological Satellite.” (abs.)(in Japanese) Programme and Abstracts, Vol-canological Society of Japan, no. 2, 1991.

14. Tootell, Betty, All 4 Engines Have Failed; TheTrue and Triumphant Story of Flight BA 009and the Jakarta Incident, Hutchinson GroupLtd., Auckland, 1992.

15. Wright, T.L. and T.C. Pierson, “Living WithVolcanoes — The U.S. Geological Survey’sVolcano Hazard Program.” U. S. GeologicalSurvey Circular 1073, 1992.

About the Author

Thomas J. Casadevall is the project chief for VolcanicHazards and Aviation Safety at the U.S. GeologicalSurvey (USGS). He coordinates USGS activities withother federal agencies and with nongovernmentalgroups in the area of aviation safety. He has workedwith the USGS Volcano Hazards Program since l978and has been a member of numerous research teamsworking at active volcano sites around the world. Heholds an M.A. in geology and a Ph.D. in geochemistry.


FSF-urged Communication Link AllowedWarning of Volcanic Eruption

FSF and FSF-CIS sponsored the seminar incooperation with the Kamchatka Regional Ad-ministration, Far East Institute of Volcanol-ogy, Aeronautical Meteorological ObservationO ff i c e o f P e t ro p a v l o v s k - K a m c h a t s k i i ,KamchatAvia Airlines, Kamtchatka Joint AviationGroup and Alpha Tours. The 60 seminar par-ticipants, including volcanologists, geologistsand other scientists, and aviation representa-tives from flight operations, air traffic controland meteorology, reached several importantconclusions during the seminar discussions,including the following:

1. The Kamchatka Region produces a widespectrum of volcanic activity, some of whichconstitute hazards to safe aircraft flight;

2. The region’s volcanic observation-stationnetwork appears to be adequate for scien-tific purposes, but additional resources couldimprove its effectiveness in alerting theaviation community of volcanic activity,which would allow for rerouting of flightsto avoid hazards;

3. The region’s scientists are competent andhighly trained; and,

4. The region’s communications network isthe weak link in warning the aviation com-munity of volcanic hazards.

The seminar served its purpose in presentingthe actual state of volcanic activity (especiallyin the CIS) and its relation to aviation safety.The results of the seminar’s discussions, whichwere presented the following week to the In-ternational Civil Aviation Organization’s (ICAO)“Volcanic Ash Hazards” meeting in Bangkok,Thailand, added up-to-date information to theICAO meeting.

FSF and FSF-CIS are considering future meet-ings in Kamchatka that will augment and comple-ment volcano-related activities by ICAO andthe U.S. Federal Aviation Administration (FAA).�

The eruption of the 10,560-feet (3200-meters)high Mt. Shivelutch Volcano on the KamchatkaPeninsula, on April 17, 1993, is only one of themost recent volcanic eruptions that underscoredthe importance of the international seminar“Volcanic Activity and Problems Related toAviation Safety,” conducted Sept. 8-12, 1992,on the Siberian peninsula of Kamchatka in theRussian Far East. [Flight Safety Foundation News,October/November/December 1992, “Volca-nic Hazards to Flight Highlight Russian Con-ference, Signals Further Opening of CIS”].

One important outcome of the seminar wasthat Flight Safety Foundation-Commonwealthof Independent States (CIS) communicated FSF’srecommendation by John H. Enders, FSF vicechairman, to the CIS Minister of Communica-tions that a direct communications link be es-tablished between the Kamchatka Region andthe West. A telephone link to Japan was estab-lished after FSF’s recommendation, but thatlink is still subject to various problems in theRussian telephone system.

The timely warning of the Mt. Shivelutch erup-tion was the first time, for instance, that Japa-nese aviation authorities had received noticedirectly from the authorities in the KamchatkaRegion of a volcanic eruption, a fairly fre-quent geological event in that part of the world.This measurable improvement in communi-cations between CIS-volcanologists and theworldwide aviation community is a direct re-sult of the seminar.

Nevertheless, goodwill, such as that shownby the personnel involved in this timelywarning, cannot be a long-term substitutefor a routine, reliable and timely commu-nications system. More work must be doneto improve the speed and accuracy of in-formation about volcanic eruptions thatmay create hazardous conditions for avia-tion operations across the northern PacificOcean and along newly opened routes acrossSiberia and the Russian Far East.


Aviation Statistics

In 1990, more than 90 percent of the 229 acci-dents involving Canadian aircraft commercialoperations occurred to Level III through LevelVI operators — small commercial operations(Figure 1). Their accident rate is estimated tobe nine per 100,000 hours, compared to 0 and1.2 for Levels I and II (large air carriers), re-spectively.

Without reliable reference data regarding thecurrent operating practices of small commer-cial operations, aviation safety investigatorsare frequently unable to determine whether aproblem discovered during the course of anaccident investigation is specific to that acci-dent or is applicable to all operations of thattype, and warrants broader safety action. There-fore, a national survey was undertaken to ob-tain operational, social, economic and psy-chological information about pilots employedin small commercial operations and to assistin the evaluation of operating prac-tices in the light of the recent Ca-nadian accident record.

Four ThousandPilots Surveyed

Survey questionnaires were sent toprofessional pilots; the target groupwas estimated to be about 4,000individuals. By the end of March1991, 2,023 responses had been re-ceived from pilots employed by largeand small air carriers; 954 of them

Canada Surveys Pilots inSmall Commercial Operations

byTransportation Safety Board of Canada

had worked for small air carriers in the preced-ing 12 months but were unemployed at thetime of the survey. Fixed-wing and rotary-wingpilots’ questionnaire files were processed andcross-tabulated together in a first stage, andthen independently to identify any significantdifferences between the two types of flying.

Pilots Are Young

The pilot population of small air carriers isyoung; 70 percent of the respondents were lessthan 40 years of age and 35 percent less than30 years of age. Only 6 percent were morethan 54 years of age. There was a lower per-centage (16 percent) of rotary-wing pilots lessthan 30 years of age.

Most respondents (96 percent) were male; 54percent were married; and 46 percent were

Charter Speciality Instructional Scheduled Executive

05

1015202530354045

2

975

1412

4

1916

44

15

21

343837 Total Population

Fixed Wing

Rotary Wing

Per

cen

t

Types of Flying

Figure 1

Source: Transportation Safety Board of Canada


e i t h e r s i n g l e , s e p a r a t e d , d i v o rc e d o rwidowed.

Pilots’ Backgrounds Vary

Low-time (less than 2,500 flight hours) fixed-wing pilots were proportionately in larger num-

bers than low-time rotary-wing pilots. At theupper end of the scale, high-time rotary-wingpilots were proportionately more numerousthan their fixed-wing aircraft colleagues (Fig-ure 2).

This overall greater flying experi-ence amongrotary-wing pilots isalso matched by a greater numberof years of experience. It is alsoobserved that, globally, about 40percent of the pilots had less thanfour years of experience and 40percent had more than nine years.The fact that less than 20 percentof thepilots have four to nine yearsof experience suggests that pilotseither continue working past nineyears as pilots for small air carri-ers or quit before having flownfor four years.

In the previous 12 months, 14 per-cent of the respondents hadexperienced an aviation occurrence (accidentor incident). In 81 percent of the cases, therespondent was pilot-in-command.

Rotary-wing PilotsPaid More

Approximately half of the air carriers that em-ployed the respondents hired 10 pilots or fewer.Rotary-wing operators employing 25 pilots ormore were reported in significantly larger pro-

portion (43 percent) than their fixed-wing counterparts (21 percent). Two-thirds of the rotary-wing pilots wereemployed by operators who hadfleets of 11 aircraft or more. Morethan a third of the respondents wereemployed by air carriers that op-erated five aircraft or less.

Rotary-wing pilots (68 percent) hadfull-time work contracts more fre-quently than fixed-wing pilots (56percent). Almost two-thirds (65 per-cent) of the respondents were em-ployed year-round. The mostcommonly reported modes of re-muneration were: fixed annual sal-

ary (29 percent); fixed daily, weekly or monthlysalary (28 percent); basic salary plus premiumfor each hour flown or mile completed (25percent); and hourly salary (20 percent). Theaverage (median) income of the respondentswhen they obtained revenue solely from fly-

ing was between C$15,000 and $29,999. Fifty-five percent of the rotary-wing pilots earnedmore than $40,000; this was true for only 20

Figure 2


Hours Flown (Total)

Per

cen

t

0-25 26-35 36-45 46-55 56-65 66 & over

0

5

10

15

20

25

30

15

46

13

78

21

1416

242525

13

2724

12

2118

Total Population

Fixed-wing

Rotary-wing

Hours

Maximum Hours Flown in a Week

Figure 3


1,000 or less 1,001-2,500 2,501-4,000 4,001 or more

0

10

20

30

40

50

60

70 66

3038

1513138

3025

11

2623

Total Population

Fixed-wing

Rotary-wing


percent of the fixed-wing pilots. Ex-militarypilots generally reported higher income thancivilian-trained pilots.

Regarding flying training on the aircraft theynormally fly, 63 percent of the respondentsfelt it was adequate, but 20 percent believedthere should have been more. Twenty percentsaid that the introduction to company opera-tions was not appropriate. A total of 14 per-cent reported that recurrent training never oc-curred or occurred less than once a year. Only61 percent of the respondents believed thatrecurrent training was enough or more thanrequired; 36 percent felt it was not enough orfar too little.

On average, 50 percent of the pilots reportedflying between zero to four hours daily, 37percent five to seven hours and 8 percent eightto 10 hours (Figure 3). The mean was 4.8 hours.The mean of the average flying hours per weekwas 19.3. In a year, rotary-wing pilots report-edly flew less than their fixed-wing counter-parts; only 14 percent flew more than 600 hours,while 29 percent of their fixed-wing colleaguesflew more than 600 hours. The yearly meanfor the group was 461.6 hours. Concerningdays off and duty days, 45 percent of the re-spondents flew more than six consecutive daysand 28 percent flew more than 12 consecutivedays often or very often.

Globally, 10 percent of the respon-dents reported that they often oralways felt pressure from theiremployer to fly when it was un-safe to do so, and 20 percent feltsuch pressure from clients and pas-sengers (Figure 4). Pressure fromthe employer to fly in illegal con-ditions was reported by 11 percentof the respondents as occurring of-ten or always; the same pressurefrom clients or passengers was feltby 17 percent.

Pressured to Fly

As many as 25 percent of the re-spondents reported not receiving

a copy of the operations manual when theybegan to work for their current employer. Whenasked whether their employer encouraged themto record unserviceabilities on a sheet sepa-rate from the aircraft journey log, 36 percentof the respondents answered that was alwaysthe case, 13 percent almost always and 14 per-cent usually.

For 14 percent of the respondents, there wereseldom or never adequate restraining devicesto satisfactorily restrain cargo or baggage in aforced landing or an emergency procedure; 12percent of the respondents always or almostalways flew with unrestrained cargo. On thesubject of cargo, 42 percent seldom or neverhad adequate weighing facilities available.

On the subject of weather facilities, 11 percentof the respondents usually flew without aweather briefing, and 11 percent always oralmost always flew without a weather brief-ing. Rotary-wing pilots stand out in this re-spect; 20 percent usually flew without a weatherbriefing and 10 percent always or almost al-ways flew without a weather briefing.

More Comments Offered

To obtain further insight, a comment sectionwas added to the questionnaire. This allowedfor the discussion of subjects that may not

Employer Other Pilots Clients/Passengers

0

10

20

30

40

50

60

70

2

18

47

33

02

33

61

1

9

4047

Never

Sometimes

Often

Always

Figure 4


Pressure to Fly in Unsafe Conditions


have been anticipated and for the expressionof a subjective response to convey the inten-sity or nuances of an issue or problem.

The relationship of mutual dependence betweenpilots and air traffic controllers was seen bysome respondents to be marred by lack of ap-preciation for the pilots’ needs and workloads.

The U.S. air traffic control system is perceivedas superior, one that many believe the Cana-dian system should emulate. The Canadianair traffic system is also viewed as anothercasualty of the recession, and safety is per-ceived by some as being compromised by fewerweather facilities, especially in sparsely popu-lated northern regions.

Poor Economic ConditionsFoster Unsafe Conditions

The comments suggest that some pilots are liv-ing near poverty, especially those in the north-ern regions, and those employed in the instruc-tional fields. The potential to exploit this labormarket is a viable option for employers be-cause of the present economic conditions, ofwhat is perceived as a lack of definition of“duty time” and of a love of flying that most ofthese pilots possess. In these times of reces-sion, the abundance of pilots allows for com-

pany operators to be very selective in hiring.According to some respondents, the selectivityis often a function of a tolerant attitude towarddangerous practices and risk taking.

Numerous comments focused on perceivedweaknesses of Transport Canada (TC) inspec-tions because of advance notice. Loose ends atan operation can be tied up, books and logscompleted or created, etc. by the time the in-spectors arrive.

The overall feeling expressed by the respon-dents is that TC’s effects are superficial, andthat there is a meaningless emphasis on papercompliance. The perception is that a legal op-eration can be feigned.

The comments sometimes convey a feeling offrustration on the part of the pilots as shownby the following excerpt from one pilot’s com-ments:

How is a co-pilot with 400 hours supposed to tell achief pilot with 20,000 hours that an aircraft isoverweight, out of center of gravity, with an im-properly tied down cargo, that the aircraft shouldn’tbe flown, when this same chief has done it hun-dreds of times without any problem? (So has thepresident, and all he wants is money from charg-ing a customer for two flights and only flyingone.) If you can answer this, and allow me to keepthe job I love more than anything, I’ll do it. �


Reports

Air Traffic Control: Justifications for Capital In-vestments Need Strengthening: Report to the Chair-man, Subcommittee on Transportation and RelatedAgencies, Committee on Appropriations, House ofRepresentatives. Washington, D.C. General Ac-counting Office (GAO)**, 1993. 27 p.: ill.

Keywords1. United States — Federal Aviation Admin-

istration — Procurement Evaluation.2. Air Traffic Control — United States —

Automation.

Summary: This report examines the U.S. Fed-eral Aviation Administration’s (FAA) processfor developing mission-need statements — state-ments that justify the need for an investmentand state what the purpose of the investmentis, how it will meet the agency’s needs, whatrisks are involved and provide a sound basisfor investment decisions.

As part of its $32 billion capital investmentplan to modernize the air traffic control (ATC)system and enhance the safety and efficiencyof air travel, the FAA reformed its acquisitionprocess in February 1991. Some mission-needstatements were disapproved and others werewithdrawn. The report said many mission-needstatements do not support the need for capitalinvestments. Of the 25 mission-need statementsexamined, 110 deficiencies in the ATC systemwere listed, possibly costing $5 billion to fix.Moreover, nearly 60 percent of the deficien-cies were merely assertions that the projectcould improve capacity or safety and shouldbe acquired. These statements contained noquantitative or qualitative information explainingperformance or maintenance problems or hownew funding would reduce delays or mainte-

Publications Received at FSFJerry Lederer Aviation Safety Library

byEditorial Staff

nance expense. The statements were seldombased upon an analysis of mission performance.

The GAO said FAA officials will have to reori-ent their thinking to first analyzing currentperformance to identify deficiencies and theneed for improved capabilities in its missionareas. The GAO recommends that the Secre-tary of Transportation direct the FAA to ap-prove only those mission-need statements thatare well supported with analytical evidenceof current and projected needs and emphasizemission analysis as the starting point for ac-quisitions.

The report includes an appendix of the FAA’snational airspace system service mission areasand examples of mission analysis processes.

Airspace System: Emerging Technologies May Of-fer Alternatives to the Instrument Landing Sys-tem: Report to the Chairman, Subcommittee onTransportation and Related Agencies, Committeeon Appropriations, House of Representatives. Wash-ington, D.C. General Accounting Office (GAO)**,1992. 39 p.: ill.

Keywords1. Instrument Landing Systems.2. Landing Aids (Aeronautics).3. Microwave Landing Systems.4. Airplanes — Landing — Technological

Innovations.

Summary: As part of its capital investmentplan to modernize the national airspace sys-tem, the U.S. Federal Aviation Administrationproposes to replace the current ground-basedprecision landing system, the instrument landingsystem (ILS), with the new microwave land-


ing system (MLS). Since the MLS decision wasmade, other alternatives for a precision land-ing system have emerged. The GAO was askedto review these alternatives, describe the ca-pabilities and costs of these precision landingsystems and identify some of the potential con-sequences of FAA’s approach to developingthese systems.

One alternative to the current system and theMLS system is an ILS enhanced with acomputer-based flight management system(FMS) on board the aircraft. Another is basedupon the U.S. satellite navigation system, theGlobal Positioning System (GPS), used in militaryapplications and that would need to be en-hanced for use in civil aviation. Each of thesesystems or mixture of systems have their ben-efits and drawbacks.

According to the report, some users have al-ready installed avionics for the ILS/FMS com-bination and the satellite-based system to supportaircraft operations, including navigation. Theywould prefer to use this equipment for preci-sion landings, rather than make an additionalinvestment in MLS equipment.

Since the costs of these systems will be sub-stantial to FAA and users, the GAO and avia-tion industry representatives are concerned thatalthough the FAA is devoting substantial re-sources to develop the MLS, the agency is com-mitting an insufficient level of resources todevelop the ILS/FMS combination and thesatellite-based systems.

To determine which alternative precision landingsystem will best meet the requirements forprecision landings, the GAO recommends thatthe FAA provide full budgetary support forthe development of alternative systems for com-paring the system’s capabilities, benefits andcosts; and prepare a mission-need statementfor precision landing systems based onrunway-to-runway determination of which sys-tem provides the most benefits at the lowestcost to both FAA and the system’s users.

The report concludes with appendices on thecosts and capabilities of the ILS and alternativeprecision landing systems under consideration.

Safety Study: Alcohol and Other Drug Involve-ment in Fatal General Aviation Accidents, 1983through 1988. Washington, D.C. U.S. NationalTransportation Safety Board (NTSB), 1992. xi,159 p. ill. Available through National Techni-cal Information Service*.

Keywords1. Aviation Toxicology.2. Flight — Physiological Aspects.3. Airplanes — Private Flying.

Summary: The NTSB conducted this study toexamine alcohol and other drug involvementin fatal general aviation accidents that occurredfrom 1983 through 1988.

Collected data was used to compare the levelof alcohol-involved accidents during this pe-riod with the level documented in the 1984statistical review of alcohol-involved aviationaccidents that occurred from 1975 through 1981.For all general aviation accidents that werefatal to the pilot-in-command, a comparisonwas made between those accidents in whichalcohol and/or drugs was cited as a cause orfactor and those accidents in which drugs oralcohol was not cited as a factor.

Comparisons were made for these two groupsin accident characteristics, flight conditions,pilot-in-command characteristics and causesand factors.

During the 1983 through 1988 period, therewas a downward trend in total general avia-tion accidents, fatal general aviation accidents,general aviation accidents fatal to the pilot-in-command, and alcohol-involved general avia-tion accidents fatal to the pilot.

According to the study, there was a decreasein the percent of toxicological tests that werepositive for fatally injured general aviationpilots from about 10 percent in the mid-1970sto about 6.0 percent in the late 1980s. Theblood alcohol concentration (BAC) of pilotsfatally injured in alcohol-involved accidentsremained high; the mean BAC of alcohol-positivepilots was nearly four times the BAC offenselevel established by the current U.S. FederalAviation Administration regulations.


The study also addresses the need for compre-hensive state laws pertaining to alcohol anddrug use in general aviation, and the need toprevent pilots from flying while impaired byalcohol or other drugs.

The study includes appendices on excerpts fromGeneral Operating and Flight Rules Related toAlcohol and other Drugs; Status of NTSB SafetyRecommendations Related to Alcohol and otherDrugs in Transportation; General Aviation DataTables; Drugs Detected in General Aviation Acci-dents 1983 through 1988; and Federal AviationRegulations Related to Offenses Involving Alco-hol or Drugs.

Light Aircraft Maintenance: General Guidance onImplementation of the Light Aircraft MaintenanceScheme (LAMS), for Aircraft not Exceeding 2730kg MTWA, with a Certificate of Airworthiness inthe Transport, Aerial Work or Private Category,CAP 520. London: U.K. Civil Aviation Authority(CAA), 1993. v, 50 p. Available through theCAA***.

Keywords1. Airplanes, Private — Maintenance and

Repair.2. Great Britain — Civil Aviation Authority.

Summary: This second edition of the May 1986CAA Civil Air Publication (CAP) contains guid-ance material for the servicing and mainte-nance of aircraft not exceeding 2,730 kilograms(6,006 pounds). This publication consolidatesall earlier information leaflets issued duringthe introduction of the LAMS schedule to guideindustry in methods of meeting published re-quirements and bring them up to date in onedocument.

This guide is divided into sections coveringowner and operator responsibilities, approvalof organizations to carry out maintenance checks,maintenance schedules, log books, pilot main-tenance, airworthiness flight tests, and engi-neering support arrangements for holders ofair operator ’s certificates (AOC).

Each section has an appendix of sample formsfor inspection, certification and maintenance

log book entries. A checklist of items, takeninto account during assessment of suitabilityfor approval of organizations to carry out main-tenance checks, is also included.

Books

The Airline Passenger’s Guerrilla Handbook: Strat-egies & Tactics for Beating the Air Travel System/George Albert Brown. Washington, D.C. BlakesPublishing Group, 1989. xviii, 396 p.: ill.

Keywords1. Air Travel — Handbooks, Manuals, etc.

Summary: Strategies have been collected fromexamination of loopholes in airlines’ rules thatmight allow passengers to carry on or check inmore baggage than the airline’s restrictionswould appear to allow, or allow passengers toreceive refunds on nonrefundable tickets.

The handbook’s contents include chapters onchoosing flights for the fastest trip; choosingflights for comfort, convenience and safety;choosing flights for the cheapest air fare; packingfor air travel; getting to the airport; waiting inthe airport; getting onto the plane; the basicsof cabin life; getting away from the airport;and dealing with special problems of air travel.

Appendices on selected U.S. airport phone num-bers and airline toll-free phone numbers arealso included. �

*U.S. Department Of CommerceNational Technical Information Service(NTIS)Springfield, VA 22161 U.S.Telephone: (703) 487-4780

**U.S. General Accounting Office (GAO)Post Office Box 6012Gaithersburg, MD 20877 U.S.Telephone: (202) 275-6241

***U.K. Civil Aviation Authority (CAA)Greville House37 Gratton RoadCheltenham, England


Accident/Incident Briefs

byEditorial Staff

Nevertheless, efforts to restore power wereunsuccessful and the engine was shut down.The aircraft landed without incident.

An investigation determined that the forwardhold door was open and that the nose conewas missing from the right engine. There was,however, no evidence of ingestion and all holdbaggage was accounted for. Maintenance andquality control personnel were cited for fail-ure to ensure that the cargo door was locked.

Strong Gust Blows AircraftOff Runway on Touchdown

Boeing 767-200. Substantial damage. No injuries.

The pilot was executing a coupled instrumentlanding system (ILS) Category I approach atnight. The autopilot was disengaged at 260 feet(79 meters) above ground level and the aircraftwas aligned on the centerline at the runwaythreshold.

Just before leveloff and touchdown, the air-craft was buffeted by a sharp gust from theleft and the right main landing gear toucheddown outside the runway edge lights. The air-craft continued to depart the runway and cameto rest alongside it with all wheels in the mud.The runway was closed for more than 24 hours.

This information provides an awareness of prob-lem areas through which such occurrences may beprevented in the future. Accident/incident briefsare based on preliminary information from gov-ernment agencies, aviation organizations, pressinformation and other sources. This informationmay not be entirely accurate.

Unsecured Cargo Door OpensDuring Initial Climb

Boeing 737-200. Minor damage. No injuries.

At 1,500 feet (454 meters) during a night depar-ture at take-off power, the crew heard a bangfrom the right engine. At the same time, theforward hold door warning light illuminated.

The flight crew reduced engine power, andno abnormal engine indications were noted.

Air Carrier


An inquiry concluded that the pilot failed tosufficiently adjust for the unexpected gust.

Turbulence Pounds Airliner;Injures Cabin Crew

BAe 146-300. Minor damage. One minor injury.

While climbing through 14,000 feet (4,242 meters),the aircraft encountered unexpected and se-vere clear air turbulence lasting nearly 10 sec-onds. The autopilot disengaged and althoughpitch and roll attitudes were not significantlydisturbed, the captain reported a strong dis-turbance in vertical and lateral acceleration.

The cabin crew, engaged in serving drinks,were thrown off their feet. One flight atten-dant struck the cabin roof before falling againsta bulkhead and fractured her elbow.

The weather forecast obtained by the crew priorto the flight had included a warning of severeturbulence reported at 17,000 feet and 32,000feet (5,151 meters and 9,697 meters).

Air TaxiCommuter

Stall Recovery Leads toForced Landing

Fokker F27 Friendship. Aircraft destroyed.Two serious injuries.

The F27 was on approach to land when thestall warning horn sounded. During recovery,both engines stopped and the pilot made aforced landing. The aircraft was destroyed byfire after impact.

An inquiry determined that both engines hadoverheated. The No.2 engine separated fromthe wing because of vibration and was foundabout three kilometers from the accident site.A report cited improper operation of propel-ler controls and poor crew coordination as con-tributing causes to the accident.

Steep Approach EndsShort of Runway

Britten-Norman Islander. Substantial damage.No injuries.

After flying several short legs, the pilot electedto land on runway 09 at the destination airport,where winds were reported 160 degrees at 10knots. The runway was 1,250 feet (379 meters)long with a slight downslope. A slope of nearly40 degrees led to the runway threshold.

On short final, in the correct landing configu-ration, the twin-engine aircraft sank rapidly.Despite application of full power, it struck anembankment 10 feet short (3 meters) and twofeet (.6 meter) below the runway threshold.

An inquiry determined that the accident wascaused by an approach steeper than usuallymade to a level runway, with a lower powersetting, and the captain’s desire to touch downclose to the threshold of a short runway withlittle headwind.

Air TaxiCommuter

Learjet Flown into SeaAfter Go-around

Gates Learjet 25. Aircraft destroyed. Twofatalities. Two minor injuries.


The pilot attempted a daylight instrument ap-proach but was too high and decided togo-around. He then attempted a visual ap-proach. Weather conditions were drizzle andrain with a ceiling of 2,970 feet (900 meters).

On final, the aircraft collided with the water,wings level in the landing configuration. Thetwo crew members and three of the five pas-sengers on board escaped. Two passengers werekilled. The aircraft sank inverted. The airportwas located near the shore of a bay along theSouth Atlantic coast.

An investigation determined that the pilot mis-judged his altitude, disregarded decision heightprocedures and failed to monitor his positionvisually.

Baron Plunges OnVOR Approach

Beech 58 Baron. Aircraft destroyed. Two fatalities.

The aircraft was attempting a VOR/DMEapproach to runway 21 with a circle to landon runway 3. The Baron descended out ofthe overcast in a near vertical nose-downattitude.

The aircraft impacted on a highway aboutone mile north of the approach end of run-way 3 and was destroyed by fire. Weather atthe time of the accident was 700 feet (212meters) overcast, visibility one mile (1.6 kilo-meters) in light snow showers and fog, andwind 050 degrees at 15 knots gusting to 20knots. An inquiry determined that the pilotlikely suffered from spatial disorientation beforethe crash.

OtherGeneralAviation

Runaway CessnaCollides with Trees

Cessna 185. Substantial damage. No injuries.

After landing and dropping off two passen-gers, the pilot had difficulty restarting theSkywagon’s engine. The pilot then attemptedto start the engine by hand turning the pro-peller.

When the engine started, the aircraft was notadequately secured and taxied without the pi-lot into trees a short distance away. The crashseriously damaged both wings.

Power Loss During PracticeFlight Injures Two

Cessna 152. Aircraft destroyed. Two serious inju-ries.

After a practice forced-landing exercise, theCessna’s engine lost power during the go-aroundat an altitude of 50 feet (15 meters).

The aircraft stalled when the pilot attempted toavoid trees and power lines. The aircraft im-pacted the ground in a nose-down attitude,seriously injuring the student pilot and instructor.


An investigation determined that the field inwhich the aircraft crashed sloped up in thedirection of the attempted go-around at an anglesimilar to the climb gradient of the aircraft.

Rotorcraft

Wire Strike Destroys Bell 206B

Bell 206B. Aircraft destroyed. One fatality.

The helicopter was on an aerial applicationmission near a utility right-of-way when itstruck wires and crashed. The aircraft caughtfire after impact and the pilot, the sole occu-pant, was killed.

The herbicide spraying mission was being con-ducted in visual meteorological conditions.

Vertigo Cuts ShortSearch-and-Rescue Operation

Hughes OH-6A. Substantial damage. Two minorinjuries.

The helicopter departed the airport at 0410 ona search-and-rescue mission for a downed mili-

tary airplane. The two pilots held commercialcertificates but were not instrument rated.

The pilot-in-command said he elected to makethe takeoff with both the landing light and the“night sun” search light on. Shortly after takeoff,at about 300 feet (91 meters) above groundlevel and with no visible horizon or groundreference, the pilot developed severe spatialdisorientation.

The pilot applied collective pitch and aft cy-clic prior to ground impact. The aircraft bouncedtwice before coming to rest. The helicopterreceived substantial damage and the two pi-lots suffered minor injuries. The weather wasclear with 10 miles (16 kilometers) visibility.

Steep Turn Snares Hiller

Hiller FH-1100. Aircraft destroyed. One fatality.

The helicopter was returning to its home baseat night when it collided with the ground andcaught fire.

Witnesses reported seeing the aircraft flyingat low altitude, and physical evidence revealedthat the first ground impact was made by themain rotor blades while the helicopter was ina left bank. The helicopter crashed in a ditchand the airframe was destroyed. The pilotwas killed in the crash. Visual meteorologicalconditions were reported at the time of thecrash.�

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