Volcanic Ash

Question 1

Volcanic Ash

Answer 1

● Explosive eruptions occur when gasses that are dissolved in magma (basically melted rock!) expand and escape violently into the air.
○ Should water contact the magma, it will be instantly turned into steam.
● Once in the air, the cooling magma will reform into microscopic rocks and glass

● To remain airborne these particles will typically have a width of about 2mm or less.
● Of course, the largest particles will be in the airspace closest to the volcano–smaller ones will be downwind.

Question 2

Radar is Not Effective

Answer 2

● Due to the fact that volcanic ash is DRY, aviation radar is not effective in detecting volcanic ash clouds.
○ Radar relies on seeing moisture to report returns!
● At the moment, there is no reliable information for the minimal ash that are acceptable for flight

St. Elmo’s fire
● St. Elmo’s fire, glowing around the plane, is usually a telltale sign of a night encounter, although rapid onset of engine problems may be the first indication

Question 3

Volcanic Ash–Prognostic Chart

Answer 3

● Volcanic Ash Advisory Centers (VAAC) are responsible for creating prognostic charts within their respective areas.
● In Canada, this is done out of Montreal, and through Environment Canada
● These charts are produced by EC only when volcanic ash threatens CDA or adjacent areas

● Each prognostic chart consists of six panels, and each panel depicts the average ash density forecast for an atmospheric layer at a specific time.
● The layers are:
○ Surface to FL200,
○ FL200 to FL350,
○ and FL350 to FL600.
● Additional charts covering a time period of up to 72 hours ahead may sometimes be produced

● The average volcanic ash density in the atmospheric layer is depicted as light, moderate or heavy

Question 4

SIGWX Charts

Answer 4

● shown with the volcanic eruption symbol at the location of the volcano.
● On the side of the chart, a box is shown containing the volcano.
● The name and international number of the volcano (if known), the latitude/longitude, and date and time of the first eruption (if known) will also be shown

● We can also check the SIGMETs, the NOTAMs or the International ASHTAMs