The aircraft's identity or type was unknown.
( ( ( The ( aircraft 's ) ) ( ( identity or ) type ) ) ( ( was unknown ) . ) )
(ROOT (S (NP (NP (DT The) (NN aircraft) (POS 's)) (NN identity) (CC or) (NN type)) (VP (VBD was) (ADJP (JJ unknown))) (. .)))
It was an unknown aircraft.  
( It ( ( was ( an ( unknown aircraft ) ) ) . ) )
(ROOT (S (NP (PRP It)) (VP (VBD was) (NP (DT an) (JJ unknown) (NN aircraft))) (. .)))