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The European Organisation for the Safety of Air Navigation
EUROCONTROL – Univ. Politehnica of Bucharest & ROMATSA Project Volcanic Ash Safety
presented at ICAO IVATF, Montreal, 11-15 July 2011
Ash Safety
Prof. dr. ing. C. BERBENTES.l. dr. ing. mat. A. BOGOIConf. dr. ing. T. CHELARUS.l. drd. Ing. C. E. CONSTANTINESCU, MBAProf. dr. ing. S. DANAILAD. DIMITRIU, PhD
Drd. Ing. V. DRAGANS.l. dr. ing. D. D. ISVORANUE. HALIC, M.D.S.l. dr. ing. L. MORARUConf. dr. dr. ing. O. T. PLETER, MBA
As. drd. A. RAJNOVEANU, M.D.Prof. dr. ing. V. STANCIUConf. dr. ing. M. STOIA-DJESKADrd. Ing. D. C. TONCUR. ULMEANU, M.D. PhD
Studies on the Measurement and the Effectsof the Volcanic Origin Particles in Suspension in the Atmosphere
on the Safety of Aircraft
Ash Safety
Presentation Title Ash Safety Research Results
Version / Date / Author 1.1 / 1.07.2011 / OTP
Beneficiary EUROCONTROL
Keywords volcanic ash, volcanic dust, sand aerosols, impact on aviation, impact on flow management
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Presentation Overview
1.Introduction – research subject, objectives, and relevance
2.Risks, vulnerability, and the scale of the phenomenon
3.Ash vs. Dust; sand aerosols; why does particle size matter?
4.Extent of the danger area: volcanic ash cloud estimation
5.Human health effects
6.Concentration measurement and forecasting
7.Selected conclusions
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• 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.
Ash Safety Project was triggered by Eyjafjalla
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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;
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• 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
Read the Scientific Report to find that … (2)
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• 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
Read the Scientific Report to find that … (3)
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Parts / Occupants Cause Effect ResponseTurbine engines fuel injection and combustor
deposits of melted ash (glassy coatings)
surge, shut-down, difficult restart in flight
idle thrust, evasive maneuver
Turbine engines clogging the turbine cooling vents
overheating idle thrust, evasive maneuver
Pitot-static clogging the sensors unreliable air speed indications
attitude-based flying, indicated air speed deducted from ground speed and wind velocity
Turbine engines abrasion with hard particles wear of fan, compressor, turbine, transmission
idle thrust, evasive maneuver
Pneumatic controls clogging the vents failure evasive maneuver
Windshield, body, wings, empennage
cracks, abrasion with hard particles
wear, opaqueness evasive maneuver
Avionics, on-board instruments
clogging air-cooling vents, electrostatic discharges
overheating, malfunction evasive maneuver
Human occupants breathing contaminated air, eye cornea contact with ash/dust particles
respiratory problems, eye damage
nose breathing, replace contact lenses with eyeglasses
Turbine engines, body and instruments metallic parts
acidity, exposure to associated SO2 and sulfurous acid
corrosion (in time) maintenance check and replacement
What can go wrong in a VA encounter
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Air Breathing Order of Magnitude
Description Affected Hardware or Liveware
1,000 m3/s High flow non-filtered air breathing
turbine engines
100 m3/s Directly exposed to airflow
windshield, empennage, body and wing
0.01 m3/s Low flow non-filtered air breathing
human occupants, Pitot-static sensors, computers, electrical engines and other air-cooled parts
Irrelevant Air breathing through filters
piston engines, air-cooled parts with air filters
Vulnerability ~ Air Breathing Flow
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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)
Vulnerability is Critical for Turbofan Engines
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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
Scale of phenomenon = 1 Cubic hectometre
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Example of quantity of contaminant accumulated in 10 minutes of flight in a
concentration of 2∙10─3 g/m3
Air Breathing Order of Magnitude
Quantity of contaminant accumulated in 10 minutes flight at a concentration of 2 10∙ ─3 g/m3
Affected Hardware or Liveware
1,000 m3/s 1.2 kg turbine engines100 m3/s 120 g windshield, empennage, body
and wing0.01 m3/s 12 mg human occupants, Pitot-static
sensors, computers, electrical engines and other air-cooled parts
Irrelevant 0 g piston engines, air-cooled parts with air filters
Terminology discriminator:
Volcanic Ash = 1/16 mm – 2 mm(Coarse ash)
Volcanic Dust < 1/16 mm(Fine ash)
Volcanic Ash Volcanic Dust
Particle size (µm) 63 - 2000 < 63
Location 1-200 NM around the volcano
Floats around the world
Sedimentation time ≈ 1/2 hour (for 1 mm) 23 Days (for 10µm)
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Volcanic Dust < 1/16 mm(Fine ash)
Volcanic Ash = 1/16 – 2 mm(Coarse ash)
Ash vs. Dust
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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 eye from all angles, clear boundary
Visible Volcanic Ash Cloud vs. Volcanic Dust Contamination
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Eruption Case Study: H=10 km, W=50 kts
Falling speed (m/s) from:
1 mm (ash) 100 m (ash)
10 m (dust)
1 m (dust)
10,000 m 6.0 0.8 0.005 8·10−5
8,000 m 5.7 0.7 0.005 8·10−5
6,000 m 5.5 0.7 0.005 7·10−5
4,000 m 5.3 0.7 0.004 7·10−5
2,000 m 5.1 0.6 0.004 7·10−5
Average falling speed (m/s)
5.5 0.7 0.005 7·10−5
Ash: Dust
1/16 mm = 62.5 mm
Ash: visible,dangerous,local / short term
Dust: Less threatening,
globe trotter /long term
1 mm (ash) 100 m (ash) 10 m (dust)
1 m (dust)
Number of particles in 1 m3 at a concentration of 2·10−3 g/m3 (2 kg/hm3)
3 2,728 2,728,370 2,728,370,453
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1 mm (ash)
100 m (ash)
10 m (dust)
1 m (dust)
Sedimentation Time (h) 0.5 4.0 555.6 39,682.5Distance travelled (NM) 25 200 27,780 1,984,125
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
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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
21
Glass Coating / Clogging by Ash vs. Dust
22
Relative Safety Risk vs. Size: 0.1-1000 m
(qualitative representation)
23
Highest-Risk Dust Particle Segment: 1-10 m
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 barriersSmaller> get out with expiration(not retained in the lungs)
Volcanic Ash / Dust / Sand Aerosols
Volcanic Ash Cloud Volcanic Dust Contamination
Sand Aerosol Contamination
Visibility Clearly visible from all angles, easily identifiable by dark colour, distinct boundary
Visible only from selected angles, hard to distinguish, visible in satellite imagery
Visible sometimes from selected angles, visible in satellite imagery
Where? Within 1-200 NM of the eruption up to 500 NM
Very large areas (>1000 NM in size)
Large areas
Typical Concentrations(1 kg/hm3 = 10−3 g/m3)
1000 kg/hm3 1-100 kg/hm3 1-100 kg/hm3
Particle size range (µm)
1-2000 1-40 1-50
Floatability in atmosphere (age)
12 Hours (due to ash-dust differentiated sedimentation)
6 Days (traces remain for years)
3 Days
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Volcanic Ash Cloud
Volcanic Dust Contamination
Sand Aerosol Contamination
Aviation Safety Risk
Serious incidents, no injury accidents
None on record None
Impact on aviation
Local Global due to misinterpretation
Maintenance issues
Source: Prof. Ulrich Schumann, DLR Institute of Atmospheric Physics, NASA Earth Observatory
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Severity vs. Frequency Safety Risk
16/02/2007 = 14 aircraft: windshield failures within 3½h19/01/2011 = 3 aircraft: windshield failures within ½h
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Ash-Sized Sand – a New Safety Concern (Denver, CO)
Source for photos: www.airliners.net
Skywest Canadair 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 .
Skywest Canadair 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
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
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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
Ash
4D
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Volcanic Ash Danger Area
Shape: defined by the variability of wind direction and amplitude of wind velocity
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Volcanic Ash Danger Area
How far does the VA travel?
Function of: H (height of eruption column), FL (flight level), and WV (wind velocity)
Eruption column H (m) 30000Flight Level (100 ft) 100Wind Velocity (kts) 50Danger area (NM) 535
Pinatubo 1991Eruption column H (m) 9000Flight Level (100 ft) 100Wind Velocity (kts) 100Danger area (NM) 236
Eyjafjalla 2010
Eruption column H (m) 3500Flight Level (100 ft) 30Wind Velocity (kts) 20Danger area (NM) 21
Etna 2011
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Why 500 NM for Pinatubo = 250 NM for Eyjafjalla?
Slide from Jacques Renvier, CFM/SNECMA, Atlantic Conference on Eyjafjallajokull, Keflavik 2010
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Why 500 NM for Pinatubo = 250 NM for Eyjafjalla?
(Kilauea, Hawaii
28 years continuous eruption)
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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)”
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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.
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Concentration measurement problems: 1. scale of phenomenon and 2. consistency
All these technologies deployed in the same area would yield different results
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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
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Future sensors are shortsighted and the scale of the phenomenon is larger
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Types of concentrations Actual Measured Forecasted Blindly (open-
loop)
Forecasted with Data
AssimilationWhen they are available (hours) never T+2H T−18H (up to
T−180H)T−18H (up to T−180H)
Uncertainty due to initial data of the eruption (orders of magnitude)
- - 2 - 3 0.2 - 1
Uncertainty due to the Eulerian diffusion model (orders of magnitude)
- - +1 every 24 hours
0.1 - 0.4
Uncertainty due to the measurement techniques
- 0.1 – 1 - -
Area coverage - Very local1 Global GlobalOverall errors 0 Significant Very large and
rapidly increasing in time
Large
Relevance to IFR flight operations - Tactical avoidance
Flight planning Flight planning
Relevance to ATM - Forecasts Validation
Airspace management, Flow management
Airspace management, Flow management
[1] Except the satellite images, which provide a global view
Airborne in‐situ hectometric concentration measurement unit
isokinetic
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VADHCMUVolcanic Ash/Dust Hectometric Concentration
Measurement Unit
1. Airborne 6 channel (3 wavelengths plus polarizations) backscattering infrared LIDAR,
2. Ground based (mobile) optical photometre, and
3. Airborne in situ hectometric concentration ‐measurement unit.
A consistent and systematic measurement technology for data assimilation:
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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!