Hold on a sec, I'm sort of serious here. A zeppelin is lighter than air -- it can just turn its engines off and drift. Plus they hardly need to be jet engines. A heavier-than-air plane is constrained to go constantly at a very high speed to maintain lift, and its failure modes are severe. A zeppelin can go much slower, so much simpler engines will do. I expect the ash is much worse for jets than for propellers, for instance.
However, the point about lower altitudes is well taken, alas.