Aviation Hazards from Volcanic Eruption Plumes - Report Example

Aviation hazards from volcanic eruption plumes: Mentoring and Mitigation Name: Lecturer: Course: Date: Table of Contents Table of Contents 2 Introduction 3 Eruption plumes, their composition and transported 3 Effects of ash clouds and volcanic gas 5 Monitoring and mitigation 7 Forecasting and monitoring Movement of Ash Cloud 8 Risk Management and Safety Strategies 9 Conclusion 9 References 10 Introduction Plumes of volcanic ash that are largely concentrated in the atmospheric air adjacent to active volcanoes are an aspect of aviation safety hazards since they jam the jet engine leading to engine failure (Vogel et al 2011). By nature, volcanic ash is tough and coarse and can quickly lead to considerable wear to the turbo-compressor blades and propellers, weaken visibility, or graze the cockpit windows. Additionally, the ash can contaminate water system and fuel and in some extreme cases jam the gears (International Symposium on Volcanic Ash and Aviation Safety 1994). This may lead to flaming out of the engines. The constituent parts of the volcanic ash have low melting point (Pyle et al 2014). This forms the basis of aviation safety as they can melt in the combustion chambers or stick to the combustors, fuel nozzles or the turbine blades leading to absolute engine malfunction. The paper examines how eruption plumes originate, their composition, as well as how the particles are transported in the plume and into the atmosphere. Eruption plumes, their composition and transported Rix et al (2010) defines volcanic ash as a by-product of volatile volcanic eruptions. Additionally, it is the finest grade of ejected solid debris at the source. According to Skybrary (2014), its estimated diameter is 2 millimetres. In describing its composition, Vainikka (2010) pointed out that it consists of smaller particles with an estimated diameter of 0.1 millimetres. These particles may rise to great levels of the plume near an eruption where they can remain suspended at the existing ambient air densities. The lofty winds carry the particles leading to ultimate dispersal in ash cloud. Usually, the ash clouds form at heights above FL200, although the lower limits of the first cloud is dependent on the altitude of the volcanic vent and the force through which the material is driven out from it (Skybrary 2014). Figure 1: Immense cloud of volcanic ash across the UK from the eruption in Iceland, some 1000 km away. Image captured on 15 April 2010 using Medium Resolution Imaging Spectrometer (MERIS) (Melina 2010). The more visible emissions are usually dominated by enormous white clouds of steam, particularly when a vent below an ice cap, which characterises what happens in Iceland. Skybrary (2014) later emphasises that the steam clouds that are incessantly emitted in the event of an eruption usually covers ash emissions that usually happens in intermittent bursts. The volcanic ash in the immediate environs of the erupted plumes consists of dissimilar variety of particle densities and sizes to those that characterise the ‘downwind dispersal clouds.’ Such clouds consist of very minute ash particles. Volcanic ash is made up of 50 percent silica, which is particularly had (Rix et al 2010). It has a melting point of nearly 1100 °C (Melina 2010). Hence, it is the risks of abrasion, melting and resolidifying in the high by-pass jet turbines that power jet transport planes, which forms the basis of the destructive effects of ash plumes on aircraft. For instance, in 1991, there was an eruption at Mount Pinatubo in the Philippines, where the volcanic ash plumes caused electric discharges, exterior abrasion and eventual engine replacement. Another example includes eruption of Eyjafjallajökull that disrupted air travel across Europe in 2010 (Rose 2010; Budd 2010). Figure 2: Volcanic ash of Eyjafjallajökull in Iceland that disrupted air travel across Europe in 2010 (Rose 2010) Effects of ash clouds and volcanic gas The effects dominant silica particles and volcanic gas (sulphur dioxide) on an aircraft cause significant concerns to aircraft safety. Vainikka (2010) explains that their hardness implies that they have an abrasive effect on an immediate surface encountered at high speed, including the interior of aircraft engine. Depending on the summit height of the volcano, they can rise up to 20 kilometres high, or higher as noted in the Pinatubo volcanic eruption in Philippines in 1991 (Rix et al 2010). The ash can disrupt or damage avionic systems of an aircraft, hence limiting a pilot’s visibility. The effusive eruptions tend to be less forceful. Still, the eruption plumes may in some cases rise to altitudes of around 9 to 11 kilometres, where they are potentially hazardous for aviation, such as the eruption in Jebel al Tair in September 2007. Forceful eruptions are longer. Example includes Chaitén volcano in 2008 that had ash clouds that stretched across Patagonia (from the Atlantic to the Pacific Ocean) (Rix et al 2010). Figure 3: 2008 Chaitén volcanic eruption showing forceful ash clouds On the other hand, Pyle et al (2014) indicates that their most substantial feature affecting aircraft engine is the idea that they have low melting point below the core temperature, usually maintained by high by-pass aircraft engines that operate beyond flight idle thrust. The absorbed silicate ash clouds melts in the hot components of the aircraft engine before fusing onto the nozzle guide vanes (NGV) and turbine blades at high pressure. Consequently, the throat area is drastically reduced while the compressor discharge and static burner amplifies rapidly causing the engine to surge (Rix et al 2010). The surge of the engine is usually accompanied by flames that burst out the engine front. The engine surge can also put off the flame in the engine combustor called flameout. The momentary or a likely fatal loss of thrust may happen in some severe cases. At such instances, successful restart of the engine is only possible once it regains fresh and uncontaminated air. However, restarting the engine at great altitudes may be tricky because of the prevailing ambient gas pressures and the lower temperatures. Additionally, the NGVs reduced flow area may hinder restarting of the engine (Karagulian et al 2010). Additionally, since the volcanic ash contains substantial electrostatic charge, once they enter the airframe of the engine’s electronic component, they potentially cause electrical failure. These pose immediate safety hazard to the plane. Monitoring and mitigation With an estimated 60 eruptions each year and increased volumes of jet aircraft traffic, Rix et al (2010) estimates that some 90 aircrafts suffer rigorous damage after their encounter with volcanic ash clouds. This may lead to transitory loss or malfunction of the engine during flight (Krueger et al 2009). According to Pyle et al (2014), because the concentration of the threshold ash means high risks to aircraft, the safest practice in safety protocol is steering clear of the volcanic clouds. Airlines such as Qantas operate ‘zero tolerance policy’ when it comes to volcanic ash. While onboard however, detecting volcanic ash clouds is not likely, as the radar of the airplane cannot sense micron size particles, and sulphur dioxide is a colourless gas. Rix et al (2010) suggest that among the key components of the volcanic clouds, sulphur dioxide is the most significant indicator for volcanic activity. Measuring the volcanic aerosol directly using aerosol absorption index or infrared (IR) sensors is essential for tracking hazardous volcanic eruptions. This relies on Infrared Atmospheric Sounding Interferometer (IASI) instrument. Still, such techniques are likely to fail when the ash components at high altitudes are covered in volcanic cloud or ash is dilute (Clarisse et al 2012). On the other hand, distinguishing the volcanic aerosol in addition to other aerosols is difficult. Therefore, sulphur dioxide is used in monitoring eruptive activities. For instance, the high sensitivity of Global Ozone Monitoring Experiment-2 (GOME-2) to low sulphur dioxide amount and its almost daily global coverage allow easy detection of most volcanic eruptions in spite of the magnitude. As indicated in Section II-A DLR offers GOME-2 SO products in near-real time two hours following sensing (Brenot et al 2014). GOME online navigation tool (found at http://wdc.dlr.de/sensors/gome2) enables locating and monitoring, even in selected regions, the amounts of sulphur dioxide, as well as the periods. Although less sensitive to sulphur dioxide at lower altitudes, the IASI measurement offers efficient night time vision and resolution because of its smaller pixel size (Rix et al 2010). The efficiency of both tools (the UV-VIS instrument GOME-2 and thermal infrared sounder IASI) in monitoring volcanic ash have been used in several eruptions, such as Okmok and Kasatochi in 2008, Jebel al Tair in 2007 (See below figure), since the presence of sulphur dioxide is a reliable indicator of volcanic eruption plumes or occurrence of ash (Kristiansen et al 2010). Figure 4: Volcanic sulphur dioxide detection by IASI instrument of the Kasatochi eruption as measured on 14 August 2008 (Rix et al 2010) Forecasting and monitoring Movement of Ash Cloud Overall, forecasting ash cloud dispersion and transport is tricky as it is anchored in mix of comparatively understandable and modelled meteorological process for predicting wind, atmospheric stability and temperature, as well as the nonexistence of sufficient real time data for use in the analogous modelling of dispersion of the ash particles (Wenzel and Zschau 2013). Combined models known as the Volcanic Ash Transport and Dispersion (VATD) models need a range of source data for describing the ash column that consists of eruption vertical distribution and cloud height, distribution of size particles and the activity period. Credible real time data on new loading, particularly at the source of eruption of the volcanic ash, is significant as it allows load dispersion modelling contribution to VATD, which may more efficiently lead to parity with the existing precise modelling mechanisms for what the wind velocity contributes to dispersal of ash cloud (Rix et al 2010). Risk Management and Safety Strategies As Rix et al (2010) recommend, effective risk management strategy would need having better understanding of the threshold of tolerance of the different engine types relative to the rate of ingestion of the ash at the loading located in downstream ash clouds. Additionally, there should be enhanced sensing or measuring of the variations of the real ash loading inside the downstream ash clouds. According to EASA’s safety strategies, operators or turbine-power helicopters and airplanes should undertake daily inspection when they operate in areas of low volcanic ash contamination in order to detect any likely erosion or volcanic ash accumulation, degradation of the system and damage to the engine. Once the ash clouds are detected, the airlines have to cancel flights until the ash components have settled (Skybrary 2014). Conclusion The constituent parts of the volcanic ash have low melting point. This forms the basis of aviation safety as they can melt in the combustion chambers or stick to the combustors, fuel nozzles or the turbine blades leading to absolute engine malfunction. As established, volcanic ash can lead to wear of the turbo-compressor blades and propellers of jet engines, weaken visibility, or graze the cockpit windows. They can also contaminate water system and fuel, and in some extreme cases jam the gears. Since they contain substantial electrostatic charge, once they enter the airframe of the engine’s electronic component, they potentially cause electrical failure. References Budd, L 2010, "A fiasco of volcanic proportions? Eyjafjallaj¨okull and the closure of European airspace," Mobilities vol 6 no 1, pp.31-40 Brenot, H., N. Theys, L. Clarisse, J. van Geffen, van Gent, J et al 2014, Support to Aviation Control Service (SACS): an online service for near-real-time satellite monitoring of volcanic plumes Natural Hazards and Earth System Sciences,” Royal Netherlands Meteorological Institute vol 14, 1099-1123, Clarisse, L, Hurtmans, D, Clerbaux, C et al 2012, "Retrieval of sulphur dioxide from the infrared atmospheric sounding interferometer (IASI)," Atmos. Meas. Tech., vol 5, pp.581–594 International Symposium on Volcanic Ash and Aviation Safety 1994, Volcanic Ash and Aviation Safety: Proceedings of the First International Symposium on Volcanic Ash and Aviation Safety, DIANE Publishing, New York Karagulian, F, Clarisse, L, Clerbaux, C, Prata, A, Hurtman, D, & Coheur, P 2010, "Detection of volcanic SO2, ash, and H2SO4 using the Infrared Atmospheric Sounding Interferometer (IASI)," Journal Of Geophysical Research, VOL. 115, pp.1-10 Kristiansen, N, Stohl, A, Prata, A, Richter, A et al 2010, "Remote sensing and inverse transport modeling of the Kasatochi eruption sulfur dioxide cloud," Journal of Geophysical Research, vol 115, pp.1-18 Krueger, A, Krotkov, N, Yang, K, Vicente, G & Schroader, W 2009, "Applications of Satellite-Based Sulfur Dioxide Monitoring," IEEE Journal Of Selected Topics In Applied Earth Observations And Remote Sensing, VOL. 2, NO. 4, pp.293-298 Melina, R 2010, "Why Are Volcanic Plumes So Dangerous?" Live Science, viewed 6 Feb 2015, Prata, F & Zecher, C 2013, "Earth Observations and Volcanic Ash,"A report from the ESA/Eumetsat Dublin workshop, 4–7 March, 2013. Pyle, D, Mather, T & Biggsm M 2014, Remote Sensing of Volcanoes and Volcanic Processes: Integrating Observation and Modelling, Geological Society of London, London Rix, M, Valks, P, Hao, N et al 2010, "Satellite Monitoring of Volcanic Sulfur Dioxide Emissions for Early Warning of Volcanic Hazards," IEEE Journal Of Selected Topics In Applied Earth Observations And Remote Sensing vol 1 no 1, pp.1-11 Rose, D 2010, "The ash cloud that never was: How volcanic plume over UK was only a twentieth of safe-flying limit and blunders led to ban," MailOnline, viewed 5 Jan 2015, Skybrary 2014, "Managing Volcanic Ash Risk to the Safety of Flights," SkyBrary Online, viewed 5 Feb 2015, Vainikka, J 2010, "Plumes and paths: The Eyjafjallajökull eruption and airspace dependencies," Nordia Geographical Publications vol 39 no 1, pp.3-14 Vogel, L., Granados, D, Norman, P et al 2011, "Early in-flight detection of SO2 via Differential Optical Absorption Spectroscopy: a feasible aviation safety measure to prevent potential encounters with volcanic plumes," Atmospheric Measurement Techniques vol. 4 no. 9, pp.1785-1804. Wenzel, F & Zschau, J 2013, Early Warning for Geological Disasters: Scientific Methods and Current Practice, Springer Science & Business Media, New York Read More

Figure 2: Volcanic ash of Eyjafjallajökull in Iceland that disrupted air travel across Europe in 2010 (Rose 2010) Effects of ash clouds and volcanic gas The effects dominant silica particles and volcanic gas (sulphur dioxide) on an aircraft cause significant concerns to aircraft safety. Vainikka (2010) explains that their hardness implies that they have an abrasive effect on an immediate surface encountered at high speed, including the interior of aircraft engine. Depending on the summit height of the volcano, they can rise up to 20 kilometres high, or higher as noted in the Pinatubo volcanic eruption in Philippines in 1991 (Rix et al 2010).

The ash can disrupt or damage avionic systems of an aircraft, hence limiting a pilot’s visibility. The effusive eruptions tend to be less forceful. Still, the eruption plumes may in some cases rise to altitudes of around 9 to 11 kilometres, where they are potentially hazardous for aviation, such as the eruption in Jebel al Tair in September 2007. Forceful eruptions are longer. Example includes Chaitén volcano in 2008 that had ash clouds that stretched across Patagonia (from the Atlantic to the Pacific Ocean) (Rix et al 2010).

Figure 3: 2008 Chaitén volcanic eruption showing forceful ash clouds On the other hand, Pyle et al (2014) indicates that their most substantial feature affecting aircraft engine is the idea that they have low melting point below the core temperature, usually maintained by high by-pass aircraft engines that operate beyond flight idle thrust. The absorbed silicate ash clouds melts in the hot components of the aircraft engine before fusing onto the nozzle guide vanes (NGV) and turbine blades at high pressure.

Consequently, the throat area is drastically reduced while the compressor discharge and static burner amplifies rapidly causing the engine to surge (Rix et al 2010). The surge of the engine is usually accompanied by flames that burst out the engine front. The engine surge can also put off the flame in the engine combustor called flameout. The momentary or a likely fatal loss of thrust may happen in some severe cases. At such instances, successful restart of the engine is only possible once it regains fresh and uncontaminated air.

However, restarting the engine at great altitudes may be tricky because of the prevailing ambient gas pressures and the lower temperatures. Additionally, the NGVs reduced flow area may hinder restarting of the engine (Karagulian et al 2010). Additionally, since the volcanic ash contains substantial electrostatic charge, once they enter the airframe of the engine’s electronic component, they potentially cause electrical failure. These pose immediate safety hazard to the plane. Monitoring and mitigation With an estimated 60 eruptions each year and increased volumes of jet aircraft traffic, Rix et al (2010) estimates that some 90 aircrafts suffer rigorous damage after their encounter with volcanic ash clouds.

This may lead to transitory loss or malfunction of the engine during flight (Krueger et al 2009). According to Pyle et al (2014), because the concentration of the threshold ash means high risks to aircraft, the safest practice in safety protocol is steering clear of the volcanic clouds. Airlines such as Qantas operate ‘zero tolerance policy’ when it comes to volcanic ash. While onboard however, detecting volcanic ash clouds is not likely, as the radar of the airplane cannot sense micron size particles, and sulphur dioxide is a colourless gas.

Rix et al (2010) suggest that among the key components of the volcanic clouds, sulphur dioxide is the most significant indicator for volcanic activity. Measuring the volcanic aerosol directly using aerosol absorption index or infrared (IR) sensors is essential for tracking hazardous volcanic eruptions. This relies on Infrared Atmospheric Sounding Interferometer (IASI) instrument. Still, such techniques are likely to fail when the ash components at high altitudes are covered in volcanic cloud or ash is dilute (Clarisse et al 2012).

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