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))) (. .)))
The transponder was not working so the aircraft showed as unknown.  
( ( The transponder ) ( ( ( was not ) ( working ( so ( ( the aircraft ) ( showed ( as unknown ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN transponder)) (VP (VBD was) (RB not) (VP (VBG working) (SBAR (IN so) (S (NP (DT the) (NN aircraft)) (VP (VBD showed) (ADJP (RB as) (JJ unknown))))))) (. .)))