On 9/11, all the hijacked aircraft were in NORAD's Northeast Air Defense Sector (also known as NEADS), which is based in Rome, New York.
( ( On 9/11 ) ( , ( ( all ( the ( hijacked aircraft ) ) ) ( ( were ( in ( ( ( ( ( NORAD 's ) ( Northeast ( Air ( Defense Sector ) ) ) ) ( -LRB- ( ( also ( known ( as NEADS ) ) ) -RRB- ) ) ) , ) ( which ( is ( based ( in ( ( Rome , ) ( New York ) ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN On) (NP (CD 9/11))) (, ,) (NP (PDT all) (DT the) (JJ hijacked) (NN aircraft)) (VP (VBD were) (PP (IN in) (NP (NP (NP (NP (NNP NORAD) (POS 's)) (NNP Northeast) (NNP Air) (NNP Defense) (NNP Sector)) (PRN (-LRB- -LRB-) (VP (ADVP (RB also)) (VBN known) (PP (IN as) (NP (NNP NEADS)))) (-RRB- -RRB-))) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ is) (VP (VBN based) (PP (IN in) (NP (NP (NNP Rome)) (, ,) (NP (NNP New) (NNP York))))))))))) (. .)))
All the hijacked aircraft were in NORAD's sector, which was supposed to be the most secure.
( ( All ( the ( hijacked aircraft ) ) ) ( ( were ( in ( ( ( ( NORAD 's ) sector ) , ) ( which ( was ( supposed ( to ( be ( the ( most secure ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PDT All) (DT the) (JJ hijacked) (NN aircraft)) (VP (VBD were) (PP (IN in) (NP (NP (NP (NNP NORAD) (POS 's)) (NN sector)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBD was) (VP (VBN supposed) (S (VP (TO to) (VP (VB be) (NP (DT the) (ADJP (RBS most) (JJ secure))))))))))))) (. .)))