Volcanic and Aviation Safety: Lessons of the Past Decade

Avoiding the -laden cloud from a volcano is the only way to guarantee that an aircraft is not damaged by the cloud’s dangerous particles, which can destroy an aircraft engine and threaten flight safety. Nature remains the ultimate force.

Thomas J. Casadevall Project Chief, Volcanic Hazards and Aviation Safety U.S. Geological Survey

Modern jet airplanes and their engines are de- aged by drifting clouds of that have signed to operate in environments that are free contaminated air routes and airport facilities. from dust and corrosive gases. Seven of these encounters are known to have caused in-flight loss of engine power to jumbo Explosive volcanic eruptions, such as the 1991 jets carrying a total of more than 2,000 passen- eruptions of Mount Pinatubo Volcano in the gers. The repair and replacement costs associ- Philippines, inject large amounts of very small ated with airplane-ash cloud encounters are also rock fragments, known as volcanic ash, and high. The repair of the Boeing 747-400 damaged corrosive gases into the upper troposphere and by an ash cloud from Redoubt Volcano, Alaska, lower stratosphere. Unfortunately, this is also U.S., in December 1989 was estimated to cost in the normal cruising altitude for jet airplane traffic. excess of US$80 million.12 Compounding the prob- lem is the fact that volcanic ash clouds are not Such explosive eruptions have occurred some- detectable by the present generation of radar where on earth about 10 times per year during instrumentation aboard aircraft. Complete avoid- the past decade.6 Many of these explosive volca- ance of volcanic ash clouds is the only proce- noes occur around the Pacific “ring of fire” and dure that guarantees flight safety. have a direct impact on air routes around the Pacific basin. [The ring of fire refers to the chain of volcanoes located northward from Panama Ash Cloud Encounters along the western coast of the United States, In Early 1980s Spurred Study westward across the Aleutian Islands, south- ward along the various island chains bordering Of Safety Issues the Asian coast, through the islands in Malaysia and then eastward back into the Pacific Ocean.] The threat of volcanic hazards to aviation safety first received public attention when several In the past 12 years, more than 60 modern jet commercial jet aircraft were damaged after airplanes, mostly jumbo jets, have been dam- flying through volcanic ash clouds from the

FLIGHT SAFETY FOUNDATION • FLIGHT SAFETY DIGEST • MAY 1993 1 May 1980 eruptions of Mount St. Helens in jetstream for thousands of miles. Although Washington, U.S. Interest in the aviation safety these ash clouds can circle the globe in a mat- issue grew rapidly in the early 1980s after ter of weeks, they usually deposit most of several jumbo jets encountered ash clouds that their ash within a few hours to a few days. had traveled several hundred miles from their Drifting ash clouds pose the greatest threat to sources. Eruptions of Galunggung Volcano in aircraft. Indonesia in 1982, Redoubt Volcano in Alaska, U.S., in 1989 and 1990, and Mount Pinatubo Mitigating the ash is complex because Volcano in 1991 caused significant damage to ash clouds are difficult to detect by conven- aircraft, including engine failures, and severely tional weather radar or visually from an air- disrupted regional air operations. Ash clouds plane. Ash clouds are very difficult to detect at from eruptions in Colombia, Italy, Japan, the night, and they may be obscured by weather United States and Zaire have also damaged clouds. Ash clouds must be tracked by relying aircraft. on volcanological observers on the ground, pi- lot reports (PIREPS), satellite observations and meteorological forecasts of ash-cloud movements. Ash Clouds Vary in Immediate communication from ground observ- Type and Severity ers and meteorologists to aircraft dispatchers and controllers, and to pilots, is essential.

Active volcanoes emit several types of plumes and clouds. Quiescent plumes consist of wa- Three Eruptions Affected ter vapor and gases with few or no rock par- Aircraft Operations Significantly ticles. They seldom rise above 20,000 feet (6,060 meters) and usually disperse within tens of miles of the volcano. Quiescent plumes are Three eruptions of the past decade have greatly not a significant threat to aviation safety. helped to focus attention on the problem of volcanic hazards and aviation safety. Each of Eruption columns are the violent, these eruptions included multiple cauliflower-shaped pillars of ash encounters between aircraft and and gas generated above a volca- drifting volcanic ash clouds. nic vent during an explosive erup- Drifting ash tion. Within tens of minutes some clouds pose the In 1982, two Boeing 747-200 pas- columns can rise to altitudes of senger jets encountered ash at night 40,000 feet (12,121 meters) to greatest threat to from separate eruptions of 100,000 feet (30,303 meters). They aircraft. Galunggung Volcano in Java, In- typically contain blocks of volca- donesia.11 In each case, pilots ob- nic rock up to several inches in served St. Elmo’s fire, noted the diameter, plus dense concentra- acrid smell of sulfur gas, observed tions of ash and gas. Eruption columns sel- fine dust quickly filling the cabin and experi- dom last for more than a few hours and only enced moderate turbulence while in the ash affect an area within a few miles of the volca- cloud.14 In both cases, volcanic ash entered the nic vent, so they pose a relatively small threat jets’ engines and caused surging, flameout and to aviation safety. However, because eruption immediate thrust loss of all four engines. Af- columns contain large blocks of rock, they must ter powerless descents of nearly 25,000 feet, be avoided by aircraft. the pilots of both aircraft eventually restarted all engines and landed safely at Jakarta. Both Drifting ash clouds consist of finely broken aircraft suffered extensive damage to engines rock fragments and gas that are carried away and exterior surfaces. by winds from a violent eruption column. Large volcanic eruptions produce clouds that enter The December 1989 to April 1990 eruption the stratosphere and may be carried by the period of Redoubt Volcano widely affected

2 FLIGHT SAFETY FOUNDATION • FLIGHT SAFETY DIGEST • MAY 1993 commercial and military airplane operations aged by ashfall, which occurred during a near Anchorage.4 These affects included re- major and covered airfields at Basa, routing and cancellation of flight operations Clark and Cubi Point with up to six inches of for some time, which significantly affected ash. The wet ash and constant ground shaking the Anchorage economy. on June 15 led to the collapse of numerous aircraft hangars and maintenance facilities at From December through February, ash clouds several airfields. Manila International Airport from Redoubt damaged five commercial jet was closed from June 15 to 19 and did not liners. The most serious incident occurred on resume normal operations until July 4. Clark December 15, 1989, when a new Boeing and Basa remain closed. 747-400 encountered a drifting ash cloud while descending to land at Anchorage. On entering At least 20 commercial jet airplanes were dam- the cloud at 25,000 feet (7,576 meters), about aged by volcanic ash. Most damage was be- 150 miles (242 kilometers) northeast of Redoubt, the pilot tried to fly out of Development of the Pinatubo Ash Cloud, the ash cloud and had climbed nearly June 15-16, 1991 3,000 feet (909 meters) before all four engines failed. The aircraft descended Heavy Lines = 3-hour Intervals 13,000 feet (3,939 meters) without power 20 before the engines were restarted and N flight resumed to Anchorage. No pas- sengers were injured, but the aircraft’s engines, avionics and exterior were dam- 06 aged extensively. Repair costs were es- 09 timated to exceed $80 million.12 12 10 Other damaging encounters between 15 jet aircraft and ash clouds from Redoubt 18 were reported on December 15 and 16, 21 1989, and February 21, 1990. Fortunately, 09 these aircraft did not experience en- 06 00 gine failures. Following the eruptions 03 and encounters on December 15 and 100 110 120 130E 16, Anchorage International Airport re- Source: Tanaka and Hamada, 199113 mained open. Most air carriers, how- ever, canceled operations for up to several Figure 1 days, and some international carriers canceled or curtailed operations through January cause of in-flight encounters with ash clouds 1990. These curtailments reduced revenues at from Pinatubo. These in-flight encounters in- Anchorage International Airport by approxi- volved 10 Boeing 747s, five DC-10s, one L- mately $2.6 million.3 1011, and one Boeing 737. Because of ash in- gestion, a total of 10 engines, including four The June 15, 1991, eruption of Mount Pinatubo engines on a single Boeing 747, were badly was the largest of the past 60 years.7 The erup- damaged and had to be replaced. Several other tion produced a huge ash cloud that moved airplanes were damaged on the ground by ash rapidly to the west over the South Sea, loading and improper removal of ash from Borneo and Indochina Peninsula (Figure 1), cockpit windows. disrupting aircraft operations over a broad area of the Philippines and Southeast Asia. Five Unlike encounters at Galunggung and Redoubt, airports in the Philippines, including Manila which caused multiple engine failures and International Airport and military airfields at occurred within 150 miles (242 kilometers) of Basa, Clark, Sangley and Cubi Point, were dam- the erupting volcano, the majority of Pinatubo

FLIGHT SAFETY FOUNDATION • FLIGHT SAFETY DIGEST • MAY 1993 3 encounters were at distances of more than and, in some cases, easily repaired. Medium- 600 miles (967 kilometers) from Pinatubo. Only term and long-term effects are considerably more two encounters occurred during landing ap- difficult to identify and are primarily related to proaches to Manila. All other encounters were the gaseous components in the volcanic cloud, to the west in the Singapore, Ho Chi Minh and especially the acid gas sulfur dioxide. Hong Kong Flight Information Regions. This large number of encounters reflected a major When a modern jet aircraft, traveling at high breakdown in the ways that information about speed, encounters a drifting cloud of sand-size the ash-cloud hazard was communicated. In rock fragments, a wide variety of damage will the Philippines, volcanologists of the Pinatubo occur and the consequences are usually evi- Volcano Observatory were aware of the erup- dent immediately. Volcanic ash is typically com- tions at the time they occurred. With access to posed of a mixture of sharp, angular fragments real-time satellite information, meteorologists of rapidly quenched volcanic glass, as well as and volcanologists in the United States were mineral and rock fragments that range in size also aware of the volcano’s activity, including from fine powder to fragments up to an eighth the speed and direction of the ash cloud’s move- of an inch in diameter. Fragments typically in- ment. The key problem was one of timely com- clude the minerals feldspar, quartz and pyrox- munication of this information to the proper ene. The ash is hard and can easily scratch and agencies in the aviation community. abrade glass, and metals. Any forward- facing surface of the airplane, such as win- dows, landing covers, leading edges of Aircraft Damage Can be the wings and the fuselage, will be damaged Immediate and Long-term (Figure 2). Because of its small size, ash also can enter very small openings in the aircraft exterior, including the air supplies for flight A range of damage may occur to an airplane instruments such as the pitot static system. that has flown through a volcanic ash cloud (Figure 2). Effects may be apparent immedi- The ingestion of volcanic ash by jet engines may ately or they may take longer to manifest them- cause serious deterioration of engine performance selves. Immediate effects are easy to identify or even engine failure (Figure 3). Since 1980, at

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Source: Thomas J. Casadevall

Diagram of Boeing 747-400 Aircraft Showing Exterior Damage from Ash Cloud Figure 2 4 FLIGHT SAFETY FOUNDATION • FLIGHT SAFETY DIGEST • MAY 1993 least seven encounters between jet-powered air- Other corrosion damage to and rub- craft and volcanic ash clouds have resulted in ber used in seals and lubricants and metal temporary engine failures. Two processes dete- components used in the airframe is not as riorate engine performance: erosion of moving easily identified. Identifying corrosion dam- engine parts, such as compressor and turbine age to these components may require long- blades, and accumulation of partially melted ash term programs of inspection and maintenance. in hot zones in the engine. Erosion of compres- Even then, corrosion by volcanic may sor blades reduces the compression efficiency of be impossible to distinguish from other envi- the engine but has not been proven to cause ronmental pollution such as salt in sea spray engine failure. Ash deposits in the hot sections and acid gases in polluted urban atmosphere. of the engines, including the nozzles, the combustor and the turbine, reduce the efficiency Because engines are typically inspected and of fuel mixing and restrict air passing through rebuilt more frequently than the rest of the the engine. This causes surging, - airplane, the problems of engine corrosion by out and immediate loss of engine thrust. This loss is the principal cause of engine Cutaway Showing failure. Areas of Damage by Ash Cloud

Air that enters the airplane cabin is taken from the engine. This air powers gen- erators and pneumatic systems through- out the aircraft and provides breathing air for passengers. The air passes through an environmental control system and is carried through ducts to appropriate COMBUSTOR parts of the aircraft.

Ash particles may abrade completely - through the duct system as well as clog filter systems designed to remove mois- ture from the air.

Flying an airplane through an ash cloud causes damage that is immediately evi- Source: Thomas J. Casadevall dent. More difficult to evaluate is the damage that occurs by repeated long- Figure 3 term exposure to the clouds of mostly gas and gas-derived particles that remain in volcanic gas may be more easily identified the stratosphere. For large eruptions, such as and addressed during regular maintenance. Mexico’s El Chichon in 1982, and Pinatubo in 1991, these gases may remain suspended in Nevertheless, the airframe and skin are most the stratosphere for years after the solid rock susceptible to long-term influence from repeated particles have settled. The sulfur dioxide in exposure to volcanic clouds. Scientists and engi- the clouds absorbs water vapor and is con- neers have not yet assessed the long-term effect verted to droplets of sulfuric acid. When air- of corrosion by acid components in volcanic clouds. craft fly in a stratosphere polluted with volca- nic aerosols, these acid droplets adhere to aircraft skins and windows and may penetrate Aircraft Also Face microcracks in those surfaces. This is most easily On-ground Ash Hazards observed in acrylic windows where the cloud- ing and crazing of acid-attacked windows It is easy to appreciate the nature of damage prompts their replacement.8,9,1 that occurs during an in-flight encounter with

FLIGHT SAFETY FOUNDATION • FLIGHT SAFETY DIGEST • MAY 1993 5 an ash cloud. However, a host of additional solutions for their cleanup efforts. The type of problems face an airplane sitting or taxiing on cleanup effort will usually depend on the amount the ground. For example, ashfall of more than of ashfall. several inches will place a considerable load on an aircraft, especially if the ash falls wet Ashfalls less than 0.25 inch (6.2 millimeters) with . Some aircraft may respond to load- can usually be handled by thoroughly wash- ing by settling back on their tail sections. Ash ing airport surfaces, if adequate water and loading also may cause hangars to collapse, drainage capacity is available. For thicker ashfalls, especially if ash falls wet and if ground shak- initial washing is discouraged because ash is ing caused by volcanic is strong likely to fill and block drainage lines. Instead, and prolonged, as it was during experience shows that accumulat- the Pinatubo eruption. ing the ash into mounds large Avoiding an enough to remove with Ash covering airport runways and ash cloud is the earthmoving equipment is the best taxiways is easily resuspended for first step. This may be followed days to weeks by wind and by only way to by washing. If ash is moved to the ground movement of aircraft for guarantee that edges of runways and taxiways, it takeoffs, landings and taxiing. In- should be removed or stabilized gestion of resuspended ash by jet an aircraft is with quick-growing grass or emul- engines, especially during full- not damaged. sified asphalt to avoid resuspension power takeoff, may be just as dam- of ash by aircraft movement or aging as ash encountered while in wind. This method was used suc- flight. When wet, ash becomes slip- cessfully at Manila International pery because of its fine grain size. Slippery Airport and Cubi Point Naval Air Station af- ash reduces the coefficient of friction between ter the 1991 eruptions of Pinatubo. tires and the runway surface, thus affecting the braking and turning performance of air- craft. Research and Experience Have Yielded Valuable Lessons Removing ash from an airplane and its en- gines must be done with care. Simply washing fine ash from an airplane’s exterior must be At considerable expense during the past de- avoided because water added to ash produces cade, some important lessons have been learned a slurry that may penetrate openings in the about the threats that volcanic ash poses to skin surface. Subsequent removal is costly and aviation safety in the air or on the ground. An may require disassembling the airplane. A simple aircraft cannot fly through an ash cloud with- three-step procedure is recommended for re- out sustaining some damage. Avoiding an ash moving ash from the surface of an airplane cloud is the only way to guarantee that an parked on the ground: (1) sweep ash away aircraft is not damaged. with a broom; (2) vacuum remaining ash with an industrial vacuum; and (3) wash away re- As existing instruments aboard aircraft sim- maining fine ash, being careful to wash away ply cannot detect or locate an ash cloud, the from openings in the airplane surface. most important lesson is that immediate com- munication to a pilot about a potential volca- Only a few airports have had to deal with nic threat is essential to successful avoidance. volcanic ashfall. One facility where carriers Three essential sources of information about and managers have experience is Kagoshima volcanic activity and ash clouds include ob- Airport in Japan, which receives frequent ashfall servations from ground-based observers to alert from nearby Sakurajima Volcano. While there and verify an eruption; from pilots, through are some common elements in the cleanup ef- pilot reports about eruptive activity and ash forts at each airport, airport managers and clouds; and from satellite observations to de- ground crews have typically relied on local tect and track ash clouds.

6 FLIGHT SAFETY FOUNDATION • FLIGHT SAFETY DIGEST • MAY 1993 No single source of information is completely of these volcanoes are located in Alaska, reliable and feedback between these three sources including 30 in the 1,000-mile-long (1,613 kilo- is essential for complete and accurate commu- meters) Aleutian Island chain. The U.S. Geo- nication. National and international organiza- logical Survey (USGS) is responsible for as- tions have initiated efforts to improve commu- sessing volcanic hazards and monitoring restless nications between volcanologists, meteorologists, volcanoes in the United States.15 Only 19 of air traffic controllers and pilots. Yet, the im- the 56 U.S. volcanoes are monitored by the provements cannot substitute for increased pi- USGS from volcano observatories located in lot awareness about what to do when an ash Hawaii, Washington and Alaska. Presently, only cloud is entered inadvertently. one of the 30 historically active Aleutian Is- land volcanoes is monitored. This gap in moni- Aircraft must avoid flying into volcanic ash toring coverage is especially critical in view of clouds. Avoiding an ash cloud may be diffi- the large number of commercial and military cult or even impossible for an airplane in flight, aircraft that use the great circle routes. especially at night. Although such an encoun- ter will almost surely result in some While the USGS efforts focus on damage to the airplane, depend- ground-based studies, the U.S. ing on the ash content of the cloud National Oceanic and Atmospheric and the duration of the encounter, If the aircraft Administration (NOAA) and the the aircrew can minimize the damage experiences U.S. Federal Aviation Administra- by reducing engine power and re- tion (FAA) monitor and track vol- versing course to escape the ash engine failure, canic ash clouds in the United States cloud. Such actions require that pilots must be with satellite imagery and pilot pilots be well informed about the reports. In 1989, NOAA and the nature of ash clouds and that they aware that FAA initiated a joint effort to track be trained in procedures to mini- engine volcanic ash clouds and to warn mize damage. pilots via notices to airmen parameters such (NOTAMs). Based on experience If the aircraft experiences engine gained from the 1989 to l990 Re- failure, pilots must be aware that as doubt eruptions and the l991 engine parameters such as tempera- and turbine speed Pinatubo eruption, the NOAA-FAA ture and turbine speed for engine effort will also formally link the starts at high altitude differ from for engine starts USGS into the process of inform- normal starts made on the ground. at high altitude ing pilots about the threat of vol- Analysis of incidents where engines canic ash clouds. failed because of ash ingestion in- differ from dicates that in some cases initial normal starts In cooperation with the Interna- restart attempts would probably tional Civil Aviation Organization have been adequate had pilots been made on the (ICAO) and the Air Line Pilots As- aware of the characteristics of high- ground. sociation (ALPA), the USGS con- altitude engine restarts. tinues to seek ways to inform and educate the aviation community For aircraft on the ground or en route toward about volcanic hazards and what steps can be a potentially hazardous ash cloud, communi- taken to mitigate and minimize an ash-air- cations between controllers, dispatchers and plane encounter — in the air and on the ground pilots can usually to successful avoid- — in ways that promote the safety of air travel. ance. This will typically mean carrying additional fuel or planning alternate routes to The growing number of ash encounters dur- avoid the contaminated airspace. ing the past decade has prompted several in- ternational efforts to evaluate and address the The United States has 56 volcanoes that have problem of volcanic hazards to aviation safety. erupted during the past 200 years. Forty-four In 1982, a Volcanic Ash Warnings group was

FLIGHT SAFETY FOUNDATION • FLIGHT SAFETY DIGEST • MAY 1993 7 organized under leadership of ICAO. Also in presents to the modern jet airplane and its 1982, the Australian Department of Aviation engines. This threat is not likely to disappear created an Airways Volcano Watch. in coming years. The best solution to the prob- lem is to avoid areas contaminated by ash. A May 1985 encounter between a Boeing Avoidance requires the coordinated efforts of 747-200 and an ash cloud from Soputan Volcano a broad group of technical specialists includ- in Sulawesi, Indonesia, prompted the Indone- ing volcanologists, meteorologists, dispatch- sian and Australian governments to form a liai- ers, pilots and controllers, all working together son committee to improve communications about to detect and track volcanic ash clouds and volcanic eruptions in the Indonesian region. to provide warnings about volcanic hazards to aviation safety. The goal of these efforts is In 1988, ICAO member states adopted amend- to avoid an area or airspace that has been ments for an International Airways Volcano contaminated by volcanic ash and corrosive Watch to provide alerts about eruptive activ- volcanic gas. ity worldwide. These efforts included devel- opment of a special form for pilots to report Changes to the technical design of airplanes volcanic events.5 and powerplants have been considered and rejected as being too costly or impractical. De- Communicating past experiences and practi- velopment, particularly in Australia, of sen- cal solutions to pilots and the airlines is key to sors carried on the airplane is in the early solving the ash-aircraft problem. The efforts stages and is a future hope to assist pilots to of a wide variety of agencies, both public and avoid ash clouds, especially for air routes over private, led to the First International Sympo- remote regions where volcanoes are largely sium on Volcanic Ash and Aviation Safety, held unmonitored. in Seattle, Washington, U.S., in July 1991.4 The symposium sought to encourage improvements Because ash clouds often drift over national in the detection, tracking and warning of vol- boundaries and between flight information canic ash hazard so that aircraft may avoid regions, regional air traffic facilities and carri- ash clouds; and to review the effects of volca- ers must be informed about potential volcanic nic ash on aircraft so that pilots who encoun- threats, not just in their local flight region, but ter ash might respond appropriately. More than in adjacent regions as well. The hazards posed 200 participants from 23 countries attended by volcanic clouds have a global scope that the symposium. requires both local and global approaches to ensure a successful solution. o The manufacturers’ principal trade associa- tion, the Aerospace Industries Association of America (AIAA), formed a Volcanic Ash References Study Committee in February 1991 and pre- sented its recommendations at the interna- 1. Bernard, A. and W.I. Rose, Jr., “The Injec- tional symposium. In connection with the tion of Sulfuric Acid Aerosols in the Strato- Seattle symposium, ALPA, the Air Transport sphere by El Chichon Volcano and Its Re- Association of America (ATA) and the Flight lated Hazards to the International Air Safety Foundation have actively communi- Traffic.” Natural Hazards, v. 3, 1990. cated about the volcanic ash problem to their members and constituents, both nationally 2. Blong, R. J., Volcanic Hazards, A Source Book on and internationally. the Effects of Eruptions, Academic Press, 1984, p. 424. Volcanic Ash Threat Will Remain in Coming Years 3. Brantley, S.R. (ed.), “The Eruption of Re- doubt Volcano, Alaska December 14, 1989- During the past decade, we have learned some August 31, 1990”: U.S. Geological Survey hard lessons about the threat that volcanic ash Circular 1061, 1990. Casadevall, T. J. (ed.),

8 FLIGHT SAFETY FOUNDATION • FLIGHT SAFETY DIGEST • MAY 1993 The First International Symposium on Vol- 11. Smith, W. S., “High-altitude Conk Out,” canic Ash and Aviation Safety, Programs Natural History, v. 92, no. 11, 1983. and Abstracts: U.S. Geological Survey Cir- cular 1065, 1991. 12. Steenblik, J.W., “Volcanic Ash: A Rain of Terra.” Air Line Pilot, June/July 1990. 4. Casadevall, T.J., in press. “The 1989-1990 Eruptions of Redoubt Volcano, Alaska; Im- 13. Tanaka, M. and N. Hamada, “The Eruption pacts on Aircraft Operations,” Journal of Cloud of Mt. Pinatubo Observed by Geo- Volcanology and Geothermal Research. stationary Meteorological Satellite.” (abs.) (in Japanese) Programme and Abstracts, Vol- 5. Fox, T., “Global Airways Volcano Watch canological Society of Japan, no. 2, 1991. Is Steadily Expanding,” ICAO Bulletin, April 1988. 14. Tootell, Betty, All 4 Engines Have Failed; The True and Triumphant Story of Flight BA 009 6. McClelland, L., T. Simkin, M. Summers, E. and the Jakarta Incident, Hutchinson Group Nielsen, and T.C. Stein, Global Volcanism Ltd., Auckland, 1992. 1975-1985. Prentice-Hall Inc., 1989. 15. Wright, T.L. and T.C. Pierson, “Living With 7. PVOT (Pinatubo Volcano Observatory Team), Volcanoes — The U.S. Geological Survey’s “Lessons from a Major Eruption: Mt. Volcano Hazard Program.” U. S. Geological Pinatubo, Philippines,” Eos, v. 72, 1991. Survey Circular 1073, 1992.

8. Rogers, J.T., “Results of El Chichon: Pre- mature Acrylic Window Crazing.” Boeing About the Author Airliner April-June 1984. Thomas J. Casadevall is the project chief for Volcanic 9. Rogers, J.T., “Results of El Chichon—Part Hazards and Aviation Safety at the U.S. Geological II.: Premature Acrylic Window Crazing Status Survey (USGS). He coordinates USGS activities with Report.” Boeing Airliner April-June 1985. other federal agencies and with nongovernmental groups in the area of aviation safety. He has worked 10. Rose, W.I., “Interaction of Aircraft and Ex- with the USGS Volcano Hazards Program since l978 plosive Eruption Clouds: A Volcanologist’s and has been a member of numerous research teams Perspective.” Aerospace Industries Associa- working at active volcano sites around the world. He tion of America Journal, v. 25, 1987. holds an M.A. in geology and a Ph.D. in geochemistry.

FLIGHT SAFETY FOUNDATION • FLIGHT SAFETY DIGEST • MAY 1993 9 FSF-urged Communication Link Allowed Warning of Volcanic Eruption

The eruption of the 10,560-feet (3200-meters) FSF and FSF-CIS sponsored the seminar in high Mt. Shivelutch Volcano on the Kamchatka cooperation with the Kamchatka Regional Ad- Peninsula, on April 17, 1993, is only one of the ministration, Far East Institute of Volcanol- most recent volcanic eruptions that underscored ogy, Aeronautical Meteorological Observation the importance of the international seminar Office of Petropavlovsk-Kamchatskii, “Volcanic Activity and Problems Related to KamchatAvia Airlines, Kamtchatka Joint Aviation Aviation Safety,” conducted Sept. 8-12, 1992, Group and Alpha Tours. The 60 seminar par- on the Siberian peninsula of Kamchatka in the ticipants, including volcanologists, geologists Russian Far East. [Flight Safety Foundation News, and other scientists, and aviation representa- October/November/December 1992, “Volca- tives from flight operations, air traffic control nic Hazards to Flight Highlight Russian Con- and meteorology, reached several important ference, Signals Further Opening of CIS”]. conclusions during the seminar discussions, including the following: One important outcome of the seminar was that Flight Safety Foundation-Commonwealth 1. The Kamchatka Region produces a wide of Independent States (CIS) communicated FSF’s spectrum of volcanic activity, some of which recommendation by John H. Enders, FSF vice constitute hazards to safe aircraft flight; chairman, to the CIS Minister of Communica- tions that a direct communications link be es- 2. The region’s volcanic observation-station tablished between the Kamchatka Region and network appears to be adequate for scien- the West. A telephone link to Japan was estab- tific purposes, but additional resources could lished after FSF’s recommendation, but that improve its effectiveness in alerting the link is still subject to various problems in the aviation community of volcanic activity, Russian telephone system. which would allow for rerouting of flights to avoid hazards; The timely warning of the Mt. Shivelutch erup- tion was the first time, for instance, that Japa- 3. The region’s scientists are competent and nese aviation authorities had received notice highly trained; and, directly from the authorities in the Kamchatka Region of a volcanic eruption, a fairly fre- 4. The region’s communications network is quent geological event in that part of the world. the weak link in warning the aviation com- This measurable improvement in communi- munity of volcanic hazards. cations between CIS-volcanologists and the worldwide aviation community is a direct re- The seminar served its purpose in presenting sult of the seminar. the actual state of volcanic activity (especially in the CIS) and its relation to aviation safety. Nevertheless, goodwill, such as that shown The results of the seminar’s discussions, which by the personnel involved in this timely were presented the following week to the In- warning, cannot be a long-term substitute ternational Civil Aviation Organization’s (ICAO) for a routine, reliable and timely commu- “Volcanic Ash Hazards” meeting in Bangkok, nications system. More must be done Thailand, added up-to-date information to the to improve the speed and accuracy of in- ICAO meeting. formation about volcanic eruptions that may create hazardous conditions for avia- FSF and FSF-CIS are considering future meet- tion operations across the northern Pacific ings in Kamchatka that will augment and comple- Ocean and along newly opened routes across ment volcano-related activities by ICAO and Siberia and the Russian Far East. the U.S. Federal Aviation Administration (FAA).o

10 FLIGHT SAFETY FOUNDATION • FLIGHT SAFETY DIGEST • MAY 1993 Aviation Statistics

Canada Surveys Pilots in Small Commercial Operations by Transportation Safety Board of Canada

In 1990, more than 90 percent of the 229 acci- had worked for small air carriers in the preced- dents involving Canadian aircraft commercial ing 12 months but were unemployed at the operations occurred to Level III through Level time of the survey. Fixed-wing and rotary-wing VI operators — small commercial operations pilots’ questionnaire files were processed and (Figure 1). Their accident rate is estimated to cross-tabulated together in a first stage, and be nine per 100,000 hours, compared to 0 and then independently to identify any significant 1.2 for Levels I and II (large air carriers), re- differences between the two types of flying. spectively.

Without reliable reference data regarding the Pilots Are Young current operating practices of small commer- cial operations, aviation safety investigators The pilot population of small air carriers is are frequently unable to determine whether a young; 70 percent of the respondents were less problem discovered during the course of an than 40 years of age and 35 percent less than accident investigation is specific to that acci- 30 years of age. Only 6 percent were more dent or is applicable to all operations of that than 54 years of age. There was a lower per- type, and warrants broader safety action. There- centage (16 percent) of rotary-wing pilots less fore, a national survey was undertaken to ob- than 30 years of age. tain operational, social, economic and psy- chological information about pilots employed Most respondents (96 percent) were male; 54 in small commercial operations and to assist percent were married; and 46 percent were in the evaluation of operating prac- tices in the light of the recent Ca- nadian accident record. Types of Flying 44 45 40 37 38 34 Total Population 35 Four Thousand Fixed Wing 30 Pilots Surveyed 25 21 Rotary Wing 19 Percent 20 16 15 14 15 12 9 Survey questionnaires were sent to 10 7 4 5 professional pilots; the target group 5 2 was estimated to be about 4,000 0 individuals. By the end of March Charter Speciality Instructional Scheduled Executive 1991, 2,023 responses had been re- Source: Transportation Safety Board of Canada ceived from pilots employed by large Figure 1 and small air carriers; 954 of them

FLIGHT SAFETY FOUNDATION • FLIGHT SAFETY DIGEST • MAY 1993 11 either single, separated, divorced or Rotary-wing Pilots widowed. Paid More

Pilots’ Backgrounds Vary Approximately half of the air carriers that em- ployed the respondents hired 10 pilots or fewer. Low-time (less than 2,500 flight hours) fixed- Rotary-wing operators employing 25 pilots or wing pilots were proportionately in larger num- more were reported in significantly larger pro- portion (43 percent) than their fixed- wing counterparts (21 percent). Two- Hours Flown (Total) thirds of the rotary-wing pilots were 70 66 employed by operators who had 60 Total Population fleets of 11 aircraft or more. More 50 Fixed-wing than a third of the respondents were employed by air carriers that op- 40 Rotary-wing 38 30 30 erated five aircraft or less. 30 23 26 25 20 15 11 13 13 Rotary-wing pilots (68 percent) had 10 8 full-time work contracts more fre- 0 quently than fixed-wing pilots (56 1,000 or less 1,001-2,500 2,501-4,000 4,001 or more percent). Almost two-thirds (65 per- Source: Transportation Safety Board of Canada cent) of the respondents were em- ployed year-round. The most Figure 2 commonly reported modes of re- muneration were: fixed annual sal- bers than low-time rotary-wing pilots. At the ary (29 percent); fixed daily, weekly or monthly upper end of the scale, high-time rotary-wing salary (28 percent); basic salary plus premium pilots were proportionately more numerous for each hour flown or mile completed (25 than their fixed-wing aircraft colleagues (Fig- percent); and hourly salary (20 percent). The ure 2). average (median) income of the respondents when they obtained revenue solely from fly- This overall greater flying experi- ence amongrotary-wing pilots is also matched by a greater number Maximum Hours Flown in a Week of years of experience. It is also 30 27 Total Population observed that, globally, about 40 25 25 25 24 24 Fixed-wing percent of the pilots had less than 21 21 four years of experience and 40 20 18 Rotary-wing 16 14 15 percent had more than nine years. 15 12 13 13

The fact that less than 20 percent Percent 10 8 7 6 of thepilots have four to nine years 4 of experience suggests that pilots 5 either continue working past nine 0 years as pilots for small air carri- 0-25 26-35 36-45 46-55 56-65 66 & over Hours ers or quit before having flown for four years. Source: Transportation Safety Board of Canada Figure 3 In the previous 12 months, 14 per- cent of the respondents had experienced an aviation occurrence (accident ing was between C$15,000 and $29,999. Fifty- or incident). In 81 percent of the cases, the five percent of the rotary-wing pilots earned respondent was pilot-in-command. more than $40,000; this was true for only 20

12 FLIGHT SAFETY FOUNDATION • FLIGHT SAFETY DIGEST • MAY 1993 percent of the fixed-wing pilots. Ex-military a copy of the operations manual when they pilots generally reported higher income than began to work for their current employer. When civilian-trained pilots. asked whether their employer encouraged them to record unserviceabilities on a sheet sepa- Regarding flying training on the aircraft they rate from the aircraft journey log, 36 percent normally fly, 63 percent of the respondents of the respondents answered that was always felt it was adequate, but 20 percent believed the case, 13 percent almost always and 14 per- there should have been more. Twenty percent cent usually. said that the introduction to company opera- tions was not appropriate. A total of 14 per- For 14 percent of the respondents, there were cent reported that recurrent training never oc- seldom or never adequate restraining devices curred or occurred less than once a year. Only to satisfactorily restrain cargo or baggage in a 61 percent of the respondents believed that forced landing or an procedure; 12 recurrent training was enough or more than percent of the respondents always or almost required; 36 percent felt it was not enough or always flew with unrestrained cargo. On the far too little. subject of cargo, 42 percent seldom or never had adequate weighing facilities available. On average, 50 percent of the pilots reported flying between zero to four hours daily, 37 On the subject of weather facilities, 11 percent percent five to seven hours and 8 percent eight of the respondents usually flew without a to 10 hours (Figure 3). The mean was 4.8 hours. weather briefing, and 11 percent always or The mean of the average flying hours per week almost always flew without a weather brief- was 19.3. In a year, rotary-wing pilots report- ing. Rotary-wing pilots stand out in this re- edly flew less than their fixed-wing counter- spect; 20 percent usually flew without a weather parts; only 14 percent flew more than 600 hours, briefing and 10 percent always or almost al- while 29 percent of their fixed-wing colleagues ways flew without a weather briefing. flew more than 600 hours. The yearly mean for the group was 461.6 hours. Concerning days off and duty days, 45 percent of the re- More Comments Offered spondents flew more than six consecutive days and 28 percent flew more than 12 consecutive To obtain further insight, a comment section days often or very often. was added to the questionnaire. This allowed for the discussion of subjects that may not Globally, 10 percent of the respon- dents reported that they often or always felt pressure from their Pressure to Fly in Unsafe Conditions employer to fly when it was un- safe to do so, and 20 percent felt Never such pressure from clients and pas- Sometimes sengers (Figure 4). Pressure from 70 61 the employer to fly in illegal con- 60 Often ditions was reported by 11 percent 50 47 Always 47 of the respondents as occurring of- 40 40 ten or always; the same pressure 33 33 from clients or passengers was felt 30 18 by 17 percent. 20 9 10 1 2 0 2 0 Pressured to Fly Employer Other Pilots Clients/Passengers Source: Transportation Safety Board of Canada As many as 25 percent of the re- spondents reported not receiving Figure 4

FLIGHT SAFETY FOUNDATION • FLIGHT SAFETY DIGEST • MAY 1993 13 have been anticipated and for the expression pany operators to be very selective in hiring. of a subjective response to convey the inten- According to some respondents, the selectivity sity or nuances of an issue or problem. is often a function of a tolerant attitude toward dangerous practices and risk taking. The relationship of mutual dependence between pilots and air traffic controllers was seen by Numerous comments focused on perceived some respondents to be marred by lack of ap- weaknesses of Transport Canada (TC) inspec- preciation for the pilots’ needs and workloads. tions because of advance notice. Loose ends at an operation can be tied up, books and logs The U.S. air traffic control system is perceived completed or created, etc. by the time the in- as superior, one that many believe the Cana- spectors arrive. dian system should emulate. The Canadian air traffic system is also viewed as another The overall feeling expressed by the respon- casualty of the recession, and safety is per- dents is that TC’s effects are superficial, and ceived by some as being compromised by fewer that there is a meaningless emphasis on paper weather facilities, especially in sparsely popu- compliance. The perception is that a legal op- lated northern regions. eration can be feigned.

The comments sometimes convey a feeling of Poor Economic Conditions frustration on the part of the pilots as shown Foster Unsafe Conditions by the following excerpt from one pilot’s com- ments:

The comments suggest that some pilots are liv- How is a co-pilot with 400 hours supposed to tell a ing near poverty, especially those in the north- chief pilot with 20,000 hours that an aircraft is ern regions, and those employed in the instruc- overweight, out of center of , with an im- tional fields. The potential to exploit this labor properly tied down cargo, that the aircraft shouldn’t market is a viable option for employers be- be flown, when this same chief has done it hun- cause of the present economic conditions, of dreds of times without any problem? (So has the what is perceived as a lack of definition of president, and all he wants is money from charg- “duty time” and of a love of flying that most of ing a customer for two flights and only flying these pilots possess. In these times of reces- one.) If you can answer this, and allow me to keep sion, the abundance of pilots allows for com- the job I love more than anything, I’ll do it. o

14 FLIGHT SAFETY FOUNDATION • FLIGHT SAFETY DIGEST • MAY 1993 Publications Received at FSF Jerry Lederer Aviation Safety Library

by Editorial Staff

Reports nance expense. The statements were seldom based upon an analysis of mission performance. Air Traffic Control: Justifications for Capital In- vestments Need Strengthening: Report to the Chair- The GAO said FAA officials will have to reori- man, Subcommittee on Transportation and Related ent their thinking to first analyzing current Agencies, Committee on Appropriations, House of performance to identify deficiencies and the Representatives. Washington, D.C. General Ac- need for improved capabilities in its mission counting Office (GAO)**, 1993. 27 p.: ill. areas. The GAO recommends that the Secre- tary of Transportation direct the FAA to ap- Keywords prove only those mission-need statements that 1. United States — Federal Aviation Admin- are well supported with analytical evidence istration — Procurement Evaluation. of current and projected needs and emphasize 2. Air Traffic Control — United States — mission analysis as the starting point for ac- Automation. quisitions.

Summary: This report examines the U.S. Fed- The report includes an appendix of the FAA’s eral Aviation Administration’s (FAA) process national airspace system service mission areas for developing mission-need statements — state- and examples of mission analysis processes. ments that justify the need for an investment and state what the purpose of the investment is, how it will meet the agency’s needs, what risks are involved and provide a sound basis Airspace System: Emerging May Of- for investment decisions. fer Alternatives to the Instrument Landing Sys- tem: Report to the Chairman, Subcommittee on As part of its $32 billion capital investment Transportation and Related Agencies, Committee plan to modernize the air traffic control (ATC) on Appropriations, House of Representatives. Wash- system and enhance the safety and efficiency ington, D.C. General Accounting Office (GAO)**, of air travel, the FAA reformed its acquisition 1992. 39 p.: ill. process in February 1991. Some mission-need statements were disapproved and others were Keywords withdrawn. The report said many mission-need 1. Instrument Landing Systems. statements do not support the need for capital 2. Landing Aids (Aeronautics). investments. Of the 25 mission-need statements 3. Microwave Landing Systems. examined, 110 deficiencies in the ATC system 4. Airplanes — Landing — Technological were listed, possibly costing $5 billion to fix. Innovations. Moreover, nearly 60 percent of the deficien- cies were merely assertions that the project Summary: As part of its capital investment could improve capacity or safety and should plan to modernize the national airspace sys- be acquired. These statements contained no tem, the U.S. Federal Aviation Administration quantitative or qualitative information explaining proposes to replace the current ground-based performance or maintenance problems or how precision landing system, the instrument landing new funding would reduce delays or mainte- system (ILS), with the new microwave land-

FLIGHT SAFETY FOUNDATION • FLIGHT SAFETY DIGEST • MAY 1993 15 ing system (MLS). Since the MLS decision was Safety Study: Alcohol and Other Drug Involve- made, other alternatives for a precision land- ment in Fatal General Aviation Accidents, 1983 ing system have emerged. The GAO was asked through 1988. Washington, D.C. U.S. National to review these alternatives, describe the ca- Transportation Safety Board (NTSB), 1992. xi, pabilities and costs of these precision landing 159 p. ill. Available through National Techni- systems and identify some of the potential con- cal Information Service*. sequences of FAA’s approach to developing these systems. Keywords 1. Aviation Toxicology. One alternative to the current system and the 2. Flight — Physiological Aspects. MLS system is an ILS enhanced with a 3. Airplanes — Private Flying. computer-based flight management system (FMS) on board the aircraft. Another is based Summary: The NTSB conducted this study to upon the U.S. satellite navigation system, the examine alcohol and other drug involvement Global Positioning System (GPS), used in military in fatal general aviation accidents that occurred applications and that would need to be en- from 1983 through 1988. hanced for use in civil aviation. Each of these systems or mixture of systems have their ben- Collected data was used to compare the level efits and drawbacks. of alcohol-involved accidents during this pe- riod with the level documented in the 1984 According to the report, some users have al- statistical review of alcohol-involved aviation ready installed avionics for the ILS/FMS com- accidents that occurred from 1975 through 1981. bination and the satellite-based system to support For all general aviation accidents that were aircraft operations, including navigation. They fatal to the pilot-in-command, a comparison would prefer to use this equipment for preci- was made between those accidents in which sion landings, rather than make an additional alcohol and/or drugs was cited as a cause or investment in MLS equipment. factor and those accidents in which drugs or alcohol was not cited as a factor. Since the costs of these systems will be sub- stantial to FAA and users, the GAO and avia- Comparisons were made for these two groups tion industry representatives are concerned that in accident characteristics, flight conditions, although the FAA is devoting substantial re- pilot-in-command characteristics and causes sources to develop the MLS, the agency is com- and factors. mitting an insufficient level of resources to develop the ILS/FMS combination and the During the 1983 through 1988 period, there satellite-based systems. was a downward trend in total general avia- tion accidents, fatal general aviation accidents, To determine which alternative precision landing general aviation accidents fatal to the pilot-in- system will best meet the requirements for command, and alcohol-involved general avia- precision landings, the GAO recommends that tion accidents fatal to the pilot. the FAA provide full budgetary support for the development of alternative systems for com- According to the study, there was a decrease paring the system’s capabilities, benefits and in the percent of toxicological tests that were costs; and prepare a mission-need statement positive for fatally injured general aviation for precision landing systems based on pilots from about 10 percent in the mid-1970s runway-to-runway determination of which sys- to about 6.0 percent in the late 1980s. The tem provides the most benefits at the lowest blood alcohol concentration (BAC) of pilots cost to both FAA and the system’s users. fatally injured in alcohol-involved accidents remained high; the mean BAC of alcohol-positive The report concludes with appendices on the pilots was nearly four times the BAC offense costs and capabilities of the ILS and alternative level established by the current U.S. Federal precision landing systems under consideration. Aviation Administration regulations.

16 FLIGHT SAFETY FOUNDATION • FLIGHT SAFETY DIGEST • MAY 1993 The study also addresses the need for compre- log book entries. A checklist of items, taken hensive state laws pertaining to alcohol and into account during assessment of suitability drug use in general aviation, and the need to for approval of organizations to carry out main- prevent pilots from flying while impaired by tenance checks, is also included. alcohol or other drugs.

The study includes appendices on excerpts from Books General Operating and Flight Rules Related to Alcohol and other Drugs; Status of NTSB Safety The Airline Passenger’s Guerrilla Handbook: Strat- Recommendations Related to Alcohol and other egies & Tactics for Beating the Air Travel System/ Drugs in Transportation; General Aviation Data George Albert Brown. Washington, D.C. Blakes Tables; Drugs Detected in General Aviation Acci- Publishing Group, 1989. xviii, 396 p.: ill. dents 1983 through 1988; and Federal Aviation Regulations Related to Offenses Involving Alco- Keywords hol or Drugs. 1. Air Travel — Handbooks, Manuals, etc.

Light Aircraft Maintenance: General Guidance on Summary: Strategies have been collected from Implementation of the Light Aircraft Maintenance examination of loopholes in airlines’ rules that Scheme (LAMS), for Aircraft not Exceeding 2730 might allow passengers to carry on or check in kg MTWA, with a Certificate of Airworthiness in more baggage than the airline’s restrictions the Transport, Aerial Work or Private Category, would appear to allow, or allow passengers to CAP 520. London: U.K. Civil Aviation Authority receive refunds on nonrefundable tickets. (CAA), 1993. v, 50 p. Available through the CAA***. The handbook’s contents include chapters on choosing flights for the fastest trip; choosing Keywords flights for comfort, convenience and safety; 1. Airplanes, Private — Maintenance and choosing flights for the cheapest air fare; packing Repair. for air travel; getting to the airport; waiting in 2. Great Britain — Civil Aviation Authority. the airport; getting onto the plane; the basics of cabin life; getting away from the airport; Summary: This second edition of the May 1986 and dealing with special problems of air travel. CAA Civil Air Publication (CAP) contains guid- ance material for the servicing and mainte- Appendices on selected U.S. airport phone num- nance of aircraft not exceeding 2,730 kilograms bers and airline toll-free phone numbers are (6,006 pounds). This publication consolidates also included. o all earlier information leaflets issued during the introduction of the LAMS schedule to guide *U.S. Department Of Commerce industry in methods of meeting published re- National Technical Information Service quirements and bring them up to date in one (NTIS) document. Springfield, VA 22161 U.S. Telephone: (703) 487-4780 This guide is divided into sections covering owner and operator responsibilities, approval **U.S. General Accounting Office (GAO) of organizations to carry out maintenance checks, Post Office Box 6012 maintenance schedules, log books, pilot main- Gaithersburg, MD 20877 U.S. tenance, airworthiness flight tests, and engi- Telephone: (202) 275-6241 neering support arrangements for holders of air operator’s certificates (AOC). ***U.K. Civil Aviation Authority (CAA) Greville House Each section has an appendix of sample forms 37 Gratton Road for inspection, certification and maintenance Cheltenham, England

FLIGHT SAFETY FOUNDATION • FLIGHT SAFETY DIGEST • MAY 1993 17 Accident/Incident Briefs

by Editorial Staff

This information provides an awareness of prob- Nevertheless, efforts to restore power were lem areas through which such occurrences may be unsuccessful and the engine was shut down. prevented in the future. Accident/incident briefs The aircraft landed without incident. are based on preliminary information from gov- ernment agencies, aviation organizations, press An investigation determined that the forward information and other sources. This information hold was open and that the nose cone may not be entirely accurate. was missing from the right engine. There was, however, no evidence of ingestion and all hold baggage was accounted for. Maintenance and quality control personnel were cited for fail- ure to ensure that the cargo door was locked. Air Carrier

Strong Gust Blows Aircraft Off Runway on Touchdown

Boeing 767-200. Substantial damage. No injuries.

The pilot was executing a coupled instrument Unsecured Cargo Door Opens landing system (ILS) Category I approach at During Initial Climb night. The autopilot was disengaged at 260 feet (79 meters) above ground level and the aircraft was aligned on the centerline at the runway Boeing 737-200. Minor damage. No injuries. threshold.

At 1,500 feet (454 meters) during a night depar- Just before leveloff and touchdown, the air- ture at take-off power, the crew heard a bang craft was buffeted by a sharp gust from the from the right engine. At the same time, the left and the right main landing gear touched forward hold door warning light illuminated. down outside the runway edge . The air- craft continued to depart the runway and came The flight crew reduced engine power, and to rest alongside it with all wheels in the mud. no abnormal engine indications were noted. The runway was closed for more than 24 hours.

18 FLIGHT SAFETY FOUNDATION • FLIGHT SAFETY DIGEST • MAY 1993 An inquiry concluded that the pilot failed to An inquiry determined that both engines had sufficiently adjust for the unexpected gust. overheated. The No.2 engine separated from the wing because of vibration and was found about three kilometers from the accident site. Turbulence Pounds Airliner; A report cited improper operation of propel- Injures Cabin Crew ler controls and poor crew coordination as con- tributing causes to the accident.

BAe 146-300. Minor damage. One minor injury. Steep Approach Ends While climbing through 14,000 feet (4,242 meters), Short of Runway the aircraft encountered unexpected and se- vere clear air turbulence lasting nearly 10 sec- onds. The autopilot disengaged and although Britten-Norman Islander. Substantial damage. pitch and roll attitudes were not significantly No injuries. disturbed, the captain reported a strong dis- turbance in vertical and lateral acceleration. After flying several short legs, the pilot elected to land on runway 09 at the destination airport, The cabin crew, engaged in serving drinks, where winds were reported 160 degrees at 10 were thrown off their feet. One flight atten- knots. The runway was 1,250 feet (379 meters) dant struck the cabin roof before falling against long with a slight downslope. A slope of nearly a bulkhead and fractured her elbow. 40 degrees led to the runway threshold.

The weather forecast obtained by the crew prior On short final, in the correct landing configu- to the flight had included a warning of severe ration, the twin-engine aircraft sank rapidly. turbulence reported at 17,000 feet and 32,000 Despite application of full power, it struck an feet (5,151 meters and 9,697 meters). embankment 10 feet short (3 meters) and two feet (.6 meter) below the runway threshold.

Air Taxi Commuter An inquiry determined that the accident was caused by an approach steeper than usually made to a level runway, with a lower power setting, and the captain’s desire to touch down close to the threshold of a short runway with little headwind.

Air Taxi Commuter Stall Recovery to Forced Landing

Fokker F27 Friendship. Aircraft destroyed. Two serious injuries.

The F27 was on approach to land when the Learjet Flown into Sea stall warning horn sounded. During recovery, After Go-around both engines stopped and the pilot made a forced landing. The aircraft was destroyed by Gates Learjet 25. Aircraft destroyed. Two fire after impact. fatalities. Two minor injuries.

FLIGHT SAFETY FOUNDATION • FLIGHT SAFETY DIGEST • MAY 1993 19 The pilot attempted a daylight instrument ap- Other proach but was too high and decided to General go-around. He then attempted a visual ap- Aviation proach. Weather conditions were drizzle and rain with a ceiling of 2,970 feet (900 meters).

On final, the aircraft collided with the water, wings level in the landing configuration. The two crew members and three of the five pas- sengers on board escaped. Two passengers were killed. The aircraft sank inverted. The airport Runaway Cessna was located near the shore of a bay along the South Atlantic coast. Collides with Trees Cessna 185. Substantial damage. No injuries. An investigation determined that the pilot mis- judged his altitude, disregarded decision height After landing and dropping off two passen- procedures and failed to monitor his position gers, the pilot had difficulty restarting the visually. Skywagon’s engine. The pilot then attempted to start the engine by hand turning the pro- peller.

Baron Plunges On When the engine started, the aircraft was not VOR Approach adequately secured and taxied without the pi- Beech 58 Baron. Aircraft destroyed. Two fatalities. lot into trees a short distance away. The crash seriously damaged both wings. The aircraft was attempting a VOR/DME approach to runway 21 with a circle to land on runway 3. The Baron descended out of Power Loss During Practice the overcast in a near vertical nose-down Flight Injures Two attitude. Cessna 152. Aircraft destroyed. Two serious inju- The aircraft impacted on a highway about ries. one mile north of the approach end of run- way 3 and was destroyed by fire. Weather at After a practice forced-landing exercise, the the time of the accident was 700 feet (212 Cessna’s engine lost power during the go-around meters) overcast, visibility one mile (1.6 kilo- at an altitude of 50 feet (15 meters). meters) in light snow showers and fog, and wind 050 degrees at 15 knots gusting to 20 The aircraft stalled when the pilot attempted to knots. An inquiry determined that the pilot avoid trees and power lines. The aircraft im- likely suffered from spatial disorientation before pacted the ground in a nose-down attitude, the crash. seriously injuring the student pilot and instructor.

20 FLIGHT SAFETY FOUNDATION • FLIGHT SAFETY DIGEST • MAY 1993 An investigation determined that the field in tary airplane. The two pilots held commercial which the aircraft crashed sloped up in the certificates but were not instrument rated. direction of the attempted go-around at an angle similar to the climb gradient of the aircraft. The pilot-in-command said he elected to make the takeoff with both the landing light and the “night sun” search light on. Shortly after takeoff, Rotorcraft at about 300 feet (91 meters) above ground level and with no visible horizon or ground reference, the pilot developed severe spatial disorientation.

The pilot applied collective pitch and aft cy- clic prior to ground impact. The aircraft bounced twice before coming to rest. The helicopter Wire Strike Destroys Bell 206B received substantial damage and the two pi- lots suffered minor injuries. The weather was Bell 206B. Aircraft destroyed. One fatality. clear with 10 miles (16 kilometers) visibility.

The helicopter was on an aerial application mission near a utility right-of-way when it Steep Turn Snares Hiller struck wires and crashed. The aircraft caught fire after impact and the pilot, the sole occu- Hiller FH-1100. Aircraft destroyed. One fatality. pant, was killed. The helicopter was returning to its home base The herbicide spraying mission was being con- at night when it collided with the ground and ducted in visual meteorological conditions. caught fire.

Witnesses reported seeing the aircraft flying Vertigo Cuts Short at low altitude, and physical evidence revealed Search-and-Rescue Operation that the first ground impact was made by the main rotor blades while the helicopter was in Hughes OH-6A. Substantial damage. Two minor a left bank. The helicopter crashed in a ditch injuries. and the airframe was destroyed. The pilot was killed in the crash. Visual meteorological The helicopter departed the airport at 0410 on conditions were reported at the time of the a search-and-rescue mission for a downed mili- crash.o

FLIGHT SAFETY FOUNDATION • FLIGHT SAFETY DIGEST • MAY 1993 21