VOLCANIC ASH

NICHOLAS SOTO

OVERVIEW• What is Volcanic Ash?

• Material composition • How is it made?

• Atmospheric Effects

• How it spreads• Damages to ecosystem

• Effects on Aviation

• Damages to aircraft• Jet engine hazards• Volcanic ash lightning

• NTSB Accident

WHAT IS VOLCANIC ASH?• Tephra

• Pulverized rock and glass• Diameter 2 mm – 0.06 mm• Very coarse and extremely hard

• 3 mechanisms of volcanic ash formation• 1). Gas release under decompression

causing magmatic eruptions• 2). Thermal contraction from chilling

on contact with water causing

phreatomagmatic eruptions• 3). Ejection of entrained particles

during steam eruptions causing

phreatic eruptions

ATMOSPHERIC EFFECTS• Volcanic ash spread

• Local winds carry ash cloud• Can reach highest layers of stratosphere

• Majority of cloud will be in the troposphere

• Jet Stream can carry ash cloud around the world• Airborne up to several months

• Damage to local community

• Can be up to 10’ deep• Collapse roofs, blocks roads• Destroys local ecosystem

• Vegetation, livestock, aquatic life

• Large amount of toxic sulfurous gases• 1783 Laki eruption in Iceland poisoned 1/5 its population • 23,000 kill in Britain alone

Chaitén volcano 2008

EFFECTS ON AVIATION• Damages to aircraft

• Sandblasting effect• Composite materials, windshield, aluminum, propellers

• Will clog pitot-static system and sensors• Vital instruments are unreliable

• Electromagnetic wave insulation• Volcanic ash particles are charged and disrupt radio

communication

• Volcanic ash lighting • Occurs during initial eruption• Forms same way as thunder storm lighting• Can cause fuel explosion and electrical equipment failure

EFFECTS ON AVIATION• Jet Engine Damage

• Large amounts of pulverized glass in ash cloud will melt in combustion chamber

• Internal parts become coated with molten glass• Will decrease performance or flame engine out• May unbalance spinning precision parts causing the

engine to tear itself apart• Emergency Procedure

• Descend below ash cloud• Extreme temperature decrease will crack glass allowing it

to be expelled enabling reigniting

http://youtu.be/KpG3cGdZY9E

NTSB REPORT• December 15, 1989 flight KLM 867 inbound for Anchorage,

Alaska

• Inadvertently came in contact with an ash cloud at 29,000’

• All 4 engine flamed out

• Aircraft descended more than 2 miles to 13,300’ before successfully reigniting at 4 engines

• Landed safely at Anchorage

• Being 747 had $80 million of damage

REFERENCES• National Transportation Safety Board. Report No.

ANC90FA020, Published 12/15/1989, http://www.ntsb.gov/aviationquery/index.aspx

• Volcanic Ash Advisory Center. http://vaac.arh.noaa.gov/

• Alaska Volcanic Observatory. http://www.avo.alaska.edu/about/index.php

• Jeppesen. Guided Flight Discovery Private Pilot, City: Englewood, CO, Published 2007

• Cox, Victoria, “Effects of Volcanic Ash on Aircraft”, May 5, 2010, http://www.faa.gov/news/testimony/news_story.cfm?newsId=11380&print=go

• http://geology.com/articles/volcanic-lightning/

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