Scientists have no standard for what concentration of ash is safe and what is a danger to aircraft, but ash cloud does scatter enough with time and distance to not threaten jets. Fallout from Mount St. Helens actually circled the globe three times before fully dispersing, but flights were grounded only within a couple hundred miles of the source.
SimonPro
Alaska airlines have been dealing with this and flying for years. They have built up their own operating procedures.
What comes up time and time again is the lack of knowledge about what concentration of Ash is safe?
Even the latest standards seem a tentative guess rather than figures based on extensive testing.
I am not an engineer or scientist but would have thought specialised engine testing, ground based in a wind tunnel where engines could be run for hours in various concentrations of ash would give a better answer?
Maybe someone could ellaborate on whether this is possible or has already been done?
Pace