The controller knew American 11 was hijacked; he was focused on searching for it after the aircraft disappeared at 8:46.
( ( ( ( ( The controller ) ( knew ( ( American 11 ) ( was hijacked ) ) ) ) ; ) ( he ( was ( focused ( on ( ( searching ( for it ) ) ( after ( ( the aircraft ) ( disappeared ( at 8:46 ) ) ) ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (DT The) (NN controller)) (VP (VBD knew) (SBAR (S (NP (NNP American) (CD 11)) (VP (VBD was) (VP (VBN hijacked))))))) (: ;) (S (NP (PRP he)) (VP (VBD was) (VP (VBN focused) (PP (IN on) (S (VP (VBG searching) (PP (IN for) (NP (PRP it))) (SBAR (IN after) (S (NP (DT the) (NN aircraft)) (VP (VBD disappeared) (PP (IN at) (NP (CD 8:46)))))))))))) (. .)))
The controller knew the aircraft had not been hijacked.
( ( The controller ) ( ( knew ( ( the aircraft ) ( ( had not ) ( been hijacked ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN controller)) (VP (VBD knew) (SBAR (S (NP (DT the) (NN aircraft)) (VP (VBD had) (RB not) (VP (VBN been) (VP (VBN hijacked))))))) (. .)))