I appreciate how desperate the situation is, but you cannot, and must not allow aircraft full of people to fly through volcanic ash - no matter how much danger the airlines are in of financial ruin, regardless of how many days your family have been stuck in Mallorca. Everyone is desperate to get the planes in the air again, but some are advocating playing games with peoples' lives in order to get there.
That is unmitigated B/S.
No-one is suggesting or recommending commercial operations through a volcanic plume. To suggest such is disingenuous.
What the consideration is that flight operations resume in areas where there is little contamination.
So would you support that flight with zero ppm of volcanic dust particulates is what is required ? If so, then sorry aircraft will be grounded across the globe ad infinitum.
There will ALWAYS be volcanic particulates in the atmosphere, our planet is on a moving crust that magma perpetually vents and breaks through the crust expelling particulates into the atmosphere.
Previous large eruptions have seen particulates circle the globe three times and remain in the atmosphere for decades.
The point of consideration is to what level, and where, the contamination exists to pose a significant threat to the integrity of of the aircraft.
Is it 30ppm, or 100ppm or 1000ppm ?
At what level will such a contamination concentration reduce TBO's on an engine, and at what level will concentrations cause an engine to shut down or cause catastrophic failure ? blade vibration through cracking of the coating on an HPC disk blade can lead to wear and subsequent catastrophic failure, such test have been conducted and they are known factors, hence why AD's and SB's are issued in accordance with manufacturers maintenance programs.
Once a determining factor has been derived, then there needs to be a consideration as to where those concentration levels exist and ASHTAM's issued to disseminate this information in order that operations can be conducted with the knowledge and data available for safe operations.
We
have all this technology and capability, however, it is
not implemented.
The primary sources of selenium are volcanic emanations and metallic sulfides associated with igneous activity. Secondary sources are biological sinks in which it has accumulated. The selenium content of black shales, coal, and petroleum is 10-20 times the crustal abundance (0.05 ppm).
Seleniferous black shales are the parent materials of the widespread seleniferous soils of the western plains of the United States. When burned, coal and petroleum containing selenium give rise to a redistribution of particulate Se0 and SeO2. The average selenium content of U. S. coal is about 3 ppm and of petroleum about 0.2 ppm. Selenium is an essential nutrient for animals and is required at a concentration of about 40 ppb in their diet; at concentrations of 4000 ppb and above, however, it becomes toxic to animals.