People sitting down in an Airplane.
People are sitting on an airplane getting ready for take off.
People sitting down an airplane does not mean they are getting ready for take off.
exists e1 s1 x1 x2 x3.(a_topic(x1) & in(e1,x3) & n_airplane(x3) & a_down(s1) & Manner(e1,s1) & Actor(e1,x2) & v_sit(e1) & (x1 = x2) & n_people(x1))
exists e2 e1 p1 s1 x1 x2.(for(e1,e2) & a_off(s1) & Manner(e2,s1) & exists s2 x3.(for(s2,x3) & n_take(x3) & Theme(s2,x1) & a_ready(s2)) & Topic(e2,p1) & Actor(e2,x1) & v_get(e2) & on(e1,x2) & n_airplane(x2) & Actor(e1,x1) & v_sit(e1) & n_people(x1))