They were planning to hijack these planes and turn them into large guided missiles, loaded with up to 11,400 gallons of jet fuel.
( They ( ( were ( planning ( to ( ( ( hijack ( these planes ) ) and ) ( ( turn them ) ( into ( ( ( large ( guided missiles ) ) , ) ( loaded ( with ( ( ( ( up to ) 11,400 ) gallons ) ( of ( jet fuel ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP They)) (VP (VBD were) (VP (VBG planning) (S (VP (TO to) (VP (VP (VB hijack) (NP (DT these) (NNS planes))) (CC and) (VP (VB turn) (NP (PRP them)) (PP (IN into) (NP (NP (JJ large) (JJ guided) (NNS missiles)) (, ,) (VP (VBN loaded) (PP (IN with) (NP (NP (QP (IN up) (TO to) (CD 11,400)) (NNS gallons)) (PP (IN of) (NP (NN jet) (NN fuel)))))))))))))) (. .)))
They were not planning to hijack the plane, but instead threaten the people sitting next to them.
( They ( ( ( were not ) ( planning ( to ( ( ( ( hijack ( the plane ) ) , ) ( but instead ) ) ( threaten ( ( the people ) ( ( sitting next ) ( to them ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP They)) (VP (VBD were) (RB not) (VP (VBG planning) (S (VP (TO to) (VP (VP (VB hijack) (NP (DT the) (NN plane))) (, ,) (CONJP (CC but) (RB instead)) (VP (VB threaten) (NP (NP (DT the) (NNS people)) (VP (VBG sitting) (ADVP (JJ next)) (PP (TO to) (NP (PRP them))))))))))) (. .)))