The New York Center controller and manager were unaware that American 11 had already crashed.
( ( ( ( The ( New ( York ( Center controller ) ) ) ) and ) manager ) ( ( ( were unaware ) ( that ( ( American 11 ) ( ( had already ) crashed ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NNP New) (NNP York) (NNP Center) (NN controller)) (CC and) (NP (NN manager))) (VP (VBD were) (ADJP (JJ unaware)) (SBAR (IN that) (S (NP (NNP American) (CD 11)) (VP (VBD had) (ADVP (RB already)) (VP (VBN crashed)))))) (. .)))
The managers were aware of the plane crashing.
( ( The managers ) ( ( were ( aware ( of ( ( the plane ) crashing ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NNS managers)) (VP (VBD were) (ADJP (JJ aware) (PP (IN of) (NP (NP (DT the) (NN plane)) (VP (VBG crashing)))))) (. .)))