Too much doom and gloom on here today when we should be concentrating on overcoming the worst of the situation.
At least there are some test flights in the air flown by people who know what where and how to conduct test flights.
Not all ash is disasterous and without the sampling one can not tell what altitudes are the most risky vs operating temperature of the engines. remember we have operated for 50 years with volcanos. A little bit of science and risk management goes a long way to live in this world.
Let the scientific knowledge and risk management do what's needed. That's the way aviation has always worked.