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Ash Safety

EUROCONTROL – Univ. Politehnica of Bucharest & ROMATSA Project Volcanic Ash Safety presented at ICAO IVATF, Montreal, 11-15 July 2011. Ash Safety. Studies on the Measurement and the Effects of the Volcanic Origin Particles in Suspension in the Atmosphere on the Safety of Aircraft.

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Ash Safety

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  1. EUROCONTROL – Univ. Politehnica of Bucharest & ROMATSA Project Volcanic Ash Safetypresented at ICAO IVATF, Montreal, 11-15 July 2011

  2. Ash Safety Studies on the Measurement and the Effects of the Volcanic Origin Particles in Suspension in the Atmosphere on the Safety of Aircraft Drd. Ing. V. DRAGAN S.l. dr. ing. D. D. ISVORANU E. HALIC, M.D. S.l. dr. ing. L. MORARU Conf. dr. dr. ing. O. T. PLETER, MBA Prof. dr. ing. C. BERBENTE S.l. dr. ing. mat. A. BOGOI Conf. dr. ing. T. CHELARU S.l. drd. Ing. C. E. CONSTANTINESCU, MBA Prof. dr. ing. S. DANAILA D. DIMITRIU, PhD • As. drd. A. RAJNOVEANU, M.D. • Prof. dr. ing. V. STANCIU • Conf. dr. ing. M. STOIA-DJESKA • Drd. Ing. D. C. TONCU • R. ULMEANU, M.D. PhD

  3. Presentation Overview • Introduction – research subject, objectives, and relevance • Risks, vulnerability, and the scale of the phenomenon • Ash vs. Dust; sand aerosols; why does particle size matter? • Extent of the danger area: volcanic ash cloud estimation • Human health effects • Concentration measurement and forecasting • Selected conclusions

  4. Ash Safety Project was triggered by Eyjafjalla • Research Subject „Studies on the Measurement and the Effects of the Volcanic Origin Particles in Suspension in the Atmosphere on the Safety of Aircraft” • Research Objectives: to provide objective, relevant, and scientifically validated information for the future decisions on the air traffic in volcanic ash contaminated atmosphere, for the best trade-off for the most fluent air traffic under the circumstances, with uncompromised flight safety.

  5. Read the Scientific Report to find that … • Visible volcanic ash cloud is dangerous to aviation, but it does not travel very far (1-200 NM, max. 550 NM down the wind in the greatest eruption in history, Pinatubo 1991); • Volcanic dust contamination in concentrations comparable to that current for sand aerosols (4∙10─3 g/m3) is not a safety issue and rather a maintenance issue (like flying at Ryadh or Cairo); • Tactical avoidance of volcanic dust contamination based on on-board instruments is not practical;

  6. Read the Scientific Report to find that … (2) • Worries about volcanic ash/dust contamination impact on the human respiratory system of the occupants of an aircraft are not justified; • Volcanic Ash/Dust Concentration is a noisy random variable, very difficult to measure with certainty and consistency; the concentration measurements should be averaged on a cubic hectometre scale (1,000,000 m3; the hectometric principle); • Concentration measuring unit: 1 kg/hm3 = 10−3 g/m3

  7. Read the Scientific Report to find that … (3) • Volcanic Dust Concentration is less important than the size distribution of particles; volcanic dust particles resulting from differential sedimentation in the natural atmospheric dispersion process do not cause abrasion and/or glass deposits inside the turbofan engine, regardless the concentration; • The best option to address volcanic ash/dust problems in the future is a quick reaction algorithm to estimate volcanic ash cloud and a prediction based on an Euler dispersion model with data assimilation from hectometric in-situ sensors

  8. What can go wrong in a VA encounter

  9. Vulnerability ~ Air Breathing Flow

  10. Vulnerability is Critical for Turbofan Engines Turbofan engines are huge vacuum cleaners, sucking an average of 1,000,000 m3 = 1 hm3 each in 10 minutes of flight The Silica particles in the core flow will be deposited as glass in the combustion chamber and on the HPT One kilogram of deposits is enough to cause turbine overheating and even engine failure (restarting is possible though outside the contaminated area)

  11. Scale of phenomenon = 1 Cubic hectometre Characteristic time scope = 10 minutes of flight = exposure of an average turbine engine to 1,000,000 m3 = 1 hm3 of air 10 minutes is the maximum exposure of an aircraft engaged in an evasive manoeuver after an unanticipated volcanic ash encounter

  12. Exampleof quantity of contaminant accumulated in 10 minutes of flight in a concentration of 2∙10─3 g/m3

  13. Terminology discriminator: Volcanic Ash = 1/16 mm – 2 mm (Coarse ash) Volcanic Dust < 1/16 mm (Fine ash)

  14. Ash vs. Dust Volcanic Dust f < 1/16 mm (Fine ash) Volcanic Ash f = 1/16 – 2 mm (Coarse ash)

  15. Visible Volcanic AshCloud vs. Volcanic DustContamination Volcanic Dust Haze (Contamination) Thin layers of dust only visible from selected viewing angles or from a far distance e.g. satellite Volcanic Ash Cloud Cloud clearly visible to naked eyefrom all angles, clear boundary

  16. Eruption Case Study: H=10 km, W=50 kts Dust Ash: Ash: visible, dangerous, local / short term Dust: Less threatening, globe trotter / long term 1/16 mm = 62.5 mm

  17. Sand Blasting Effect on Particle Size Effects of particle impact velocity and particle size on substrate roughness, from Weidenhaupt, W., 1970, Über den Einfluß der Entzunderungs- und Ziehbedingungen auf die, Oberflächen-Feingestalt von Stab- und Profilstahl, Dissertation, RWTH Aachen, Germany. as referenced by Momber, A., 2008, Blast Cleaning Technology, Springer

  18. Abrasion Caused by Ash vs. Dust Ash follows airflow streamlines imperfectly and impacts walls: inertial forces > aerodynamic forces Dust follows airflow streamlines: inertial forces << aerodynamic forces

  19. Glass Coating / Clogging by Ash vs. Dust

  20. Relative Safety Risk vs. Size: 0.1-1000 mm (qualitative representation)

  21. Highest-Risk Dust Particle Segment: 1-10 mm Turbofan engines (tests on simulated engines): Larger> The turbofan functions like a centrifugal separator (no issue with the volcanic ash/dust in the by-pass flow) Smaller> Particles exit the engine without touching any wall Human respiratory system: Larger> filtered by body barriers Smaller> get out with expiration (not retained in the lungs)

  22. Volcanic Ash / Dust / Sand Aerosols

  23. Source: Prof. Ulrich Schumann, DLR Institute of Atmospheric Physics, NASA Earth Observatory

  24. Severity vs. Frequency Safety Risk

  25. Ash-Sized Sand – a New Safety Concern (Denver, CO) 16/02/2007 = 14 aircraft: windshield failures within 3½h 19/01/2011 = 3 aircraft: windshield failures within ½h Delta Airlines Boeing 757-200, flight DL-1916 from Denver, CO to Atlanta, GA (USA), during initial climb out of runway 34L reported a cracked windshield and returned to Denver SkywestCanadair CRJ-200 on behalf of United Airlines, registration N978SW performing flight OO-6576/UA-6576 from Denver, CO (USA) to Winnipeg, MB (Canada), reported a windshield cracked during initial climb out of runway 34L and returned to Denver SkywestCanadair CRJ-700 on behalf of United Airlines, flight OO-6761/UA-6761 from Denver, CO to Cleveland, OH (USA), reported a cracked windshield during initial climb out of runway 34R and returned to Denver . Source for photos: www.airliners.net

  26. Future Eruption First Reaction Checklist • Location of the eruption / time: LAT, LONG, HHMMz, DDMMYY {repeat until eruption ends} • How tall is the eruption column? ECH (m AMSL) • Download wind profile in the area (e.g. from NOAA): WD/WV • Calculate how far will the volcanic ash cloud go: VAMAX • Draw a contour with VAMAX as major axis on the map: DA Ash4D

  27. Volcanic Ash Danger Area Shape: defined by the variability of wind direction and amplitude of wind velocity

  28. Volcanic Ash Danger Area How far does the VA travel? Function of: H (height of eruption column), FL (flight level), and WV (wind velocity) Pinatubo 1991 Eyjafjalla 2010 Etna 2011

  29. Why 500 NM for Pinatubo = 250 NM for Eyjafjalla? Slide from Jacques Renvier, CFM/SNECMA, Atlantic Conference on Eyjafjallajokull, Keflavik 2010

  30. Why 500 NM for Pinatubo = 250 NM for Eyjafjalla? (Kilauea, Hawaii 28 years continuous eruption)

  31. Conclusions on Human Health Effects What was studied: passengers (short-term) and crew (long-term) exposure to volcanic dust concentrations of 4∙10─3 g/m3 “Well under limits for short time exposure and even lower than those for chronic exposure” “Reasonable to anticipate no risk for silicosis or lung cancer in passengers and crew members” “Concentration lower than environmental Silica aerosols in some parts of the world (e.g. Ryadh, Cairo)”

  32. Concentration: volatile, noisy, measured indirectly Direct and consistent methods to measure concentration in real time: none Indirect methods, subject to large methodical errors and measuring historical values of concentration along a line of sight/movement: • In-situ sampling; • Ground up-looking LIDAR; • Airborne down-looking LIDAR; • Ground optical photometre; • Satellite infrared image.

  33. Concentrationmeasurement problems: 1. scale of phenomenon and 2. consistency All these technologies deployed in the same area would yield different results

  34. Hectometric Principle: Why do concentration measurements require averaging at the 1 hm3 scale? In this example we assume we want to measure the brightness of a halftone image

  35. Future sensors are shortsighted and the scale of the phenomenon is larger

  36. [1]Except the satellite images, which provide a global view

  37. Airborne in‐situ hectometric concentration measurement unit isokinetic

  38. VADHCMU Volcanic Ash/Dust Hectometric Concentration Measurement Unit A consistent and systematic measurement technology for data assimilation: • Airborne 6 channel (3 wavelengths plus polarizations) backscattering infrared LIDAR, • Ground based (mobile) optical photometre, and • Airborne in‐situ hectometric concentration measurement unit.

  39. Selected Conclusions • Extending the term of volcanic ash cloud as per ICAO Doc9691 to the volcanic dust haze is wrong and misleading; • Size of the particles matters more than concentration as impact on aircraft and aircraft turbofan engines; • Predicting concentrations using a dispersion model with data assimilation from a systematic daily measurement scheme using hectometric in-situ samplers is the best choice for a way forward; • Immediate reaction to a VA threat should be based on a simple kinematic model of the extension of the volcanic ash cloud and not on chasing the dust going round the globe. Please, read the final report for more!

  40. Thanks for your attention

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