It has been discussed earlier on in this thread but my query did relate to why ALL commercial air traffic in UK airspace has to be grounded in the wake of this volcanic eruption (or 'planes' as the media constantly refer them to as
).
The focus is on jet turbine AIRCRAFT but there are of course a large proportion of Turbo Prop a/c in commercial service - ATR 42/ Dash 8/ Saab 340 etc and as these engines use a gas turbine to drive the propeller, I assume they are still subject to similar effects of Volcanic ash and are therefore not permitted to fly in such conditions?