A helicopter and a small plane are in the air.
All aircraft around the world has been grounded due to a volcanic eruption.
A helicopter and small plane are flying, so all aircraft cannot have been grounded.
exists p1 s1 x1 x2 x3 x4.(n_air(x4) & in(x1,x4) & subset_of(x3,x1) & n_plane(x3) & a_small(s1) & Theme(s1,x3) & subset_of(x2,x1) & n_helicopter(x2))
exists x2.(n_world(x2) & all x1.(n_aircraft(x1) -> exists e1 s1 x3.(r_due(e1) & to(e1,x3) & n_eruption(x3) & a_volcanic(s1) & Theme(s1,x3) & Theme(e1,x1) & v_ground(e1) & around(x1,x2))))