Data Series 545
Information about reported encounters of aircraft with volcanic ash clouds from 1953 through 2009 has been compiled to document the nature and scope of risks to aviation from volcanic activity. The information, gleaned from a variety of published and other sources, is presented in database and spreadsheet formats; the compilation will be updated as additional encounters occur and as new data and corrections come to light. The effects observed by flight crews and extent of aircraft damage vary greatly among incidents, and each incident in the compilation is rated according to a severity index. Of the 129 reported incidents, 94 incidents are confirmed ash encounters, with 79 of those having various degrees of airframe or engine damage; 20 are low-severity events that involve suspected ash or gas clouds; and 15 have data that are insufficient to assess severity. Twenty-six of the damaging encounters involved significant to very severe damage to engines and (or) airframes, including nine encounters with engine shutdown during flight. The average annual rate of damaging encounters since 1976, when reporting picked up, has been approximately 2 per year. Most of the damaging encounters occurred within 24 hours of the onset of ash production or at distances less than 1,000 kilometers from the source volcanoes. The compilation covers only events of relatively short duration for which aircraft were checked for damage soon thereafter; documenting instances of long-term repeated exposure to ash (or sulfate aerosols) will require further investigation.
Of 38 source volcanoes, 8 have caused 5 or more encounters, of which the majority were damaging: Augustine (United States), Chaiten (Chile), Mount St. Helens (United States), Pacaya (Guatemala), Pinatubo (Philippines), Redoubt (United States), Sakura-jima (Japan), and Soufriere Hills (Montserrat, Lesser Antilles, United Kingdom). Aircraft have been damaged by eruptions ranging from small, recurring episodes to very large, infrequent events. Moderate-size (Volcanic Explosivity Index 3) eruptions are responsible for nearly half of the damaging encounters. Vigilance is required during the early phases of eruptive activity when data about ash emission may be the most limited and warning capabilities the most strained, yet the risk the greatest. The risk-mitigation strategy for minimizing damaging encounters continues to rely on the combination of real-time volcano monitoring and rapid eruption reporting, detection and tracking of ash clouds in the atmosphere using satellite-based sensors, dispersion modeling to forecast expected ash-cloud movement, and global dissemination of specialized warning messages.
To obtain the entire Data Series 545 report, download the text file and appendixes 1-4, which are available as separate files. Click on the links at right.
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Version 1.0, First posted December 7, 2010
Text (428 KB)
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Guffanti, Marianne, Casadevall, T.J., and Budding, Karin, 2010, Encounters of aircraft with volcanic ash clouds; A compilation of known incidents, 1953–2009: U.S. Geological Survey Data Series 545, ver. 1.0, 12 p., plus 4 appendixes including the compilation database [http://pubs.usgs.gov/ds/545/].
Characteristics of Encounters
Severity of Encounters
Frequency of Encounters
Times and Distances of Encounters from Source Volcanoes
Duration of Encounters
Appendix 1A. Compilation of Encounters of Aircraft with Volcanic Ash Clouds, 1953–2009, as a Microsoft Access Database File (.mdb)
Appendix 1B. Compilation of Encounters of Aircraft with Volcanic Ash Clouds, 1953–2009, as a Microsoft Excel 93-2007 Spreadsheet File (.xls)
Appendix 2. Explanation of Database Fields and Disclaimer
Appendix 3. Sources of Data in the Database
Appendix 4. Severity Factors for Each Incident in Appendix 1, Documenting How Severity Class was Assigned