Slingy - some air ambulances are allowed to fly, others are not - it depends on the company policy. The SAR Force is allowed to fly for SAROps but only those outside of the red area on th VAC maps issued by the met office can fly for training.
I have flown twice on SAROPs today and there is a light dusting of particulate on the nose of the aircraft after each one - our engines do have sand filters but there is some discussion about whether the particulate size is too small to be filtered by them so we are comp washing the engines after each flight.
The long and short of it is that there is ash in the air but of very low concentration - is this a big short term risk to engines? I don't believe so or we wouldn't be flying at all.
I think the same is probably true for airliners providing they stay VMC - there may be long term engineering penalties but the cost of those is bound to be massively outweighed by the lost revenue of not flying at all.
Flying in VMC conditions that we have had for the last few days is not going to put out the flame on the engines no matter how much the doomsayers may claim - it might take some hours off them and they might need more frequent washes and inspections but this blanket ban on flying is ludicrous.
What this process has highlighted is the lack of adequate measuring capability and any form of assessment of particulate levels Vs risk to flying.
We are mainly relying on the met office who on Thursday were saying it wasn't a met issue at all and they were only advising the govt on the effects of the winds spreading the cloud.