On Flight 93, however, the takeover took place 46 minutes after takeoff and there were only four hijackers.
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(ROOT (S (PP (IN On) (NP (NNP Flight) (CD 93))) (, ,) (S (ADVP (RB however)) (, ,) (NP (DT the) (NN takeover)) (VP (VBD took) (NP (NN place)) (NP (CD 46) (NNS minutes)) (PP (IN after) (NP (NN takeoff))))) (CC and) (S (NP (EX there)) (VP (VBD were) (NP (QP (RB only) (CD four)) (NNS hijackers)))) (. .)))
The hijacking of flight 93 was unsuccessful until about 6 hours in.
( ( ( The hijacking ) ( of ( flight 93 ) ) ) ( ( ( was ( unsuccessful ( until ( ( about 6 ) hours ) ) ) ) in ) . ) )
(ROOT (S (NP (NP (DT The) (NN hijacking)) (PP (IN of) (NP (NN flight) (CD 93)))) (VP (VBD was) (ADJP (JJ unsuccessful) (PP (IN until) (NP (QP (RB about) (CD 6)) (NNS hours)))) (PP (IN in))) (. .)))