FAA headquarters began to follow the hijack protocol but did not contact the NMCC to request a fighter escort.
( ( FAA headquarters ) ( ( ( ( began ( to ( follow ( the ( hijack protocol ) ) ) ) ) but ) ( ( did not ) ( contact ( the ( NMCC ( to ( request ( a ( fighter escort ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP FAA) (NNS headquarters)) (VP (VP (VBD began) (S (VP (TO to) (VP (VB follow) (NP (DT the) (NN hijack) (NN protocol)))))) (CC but) (VP (VBD did) (RB not) (VP (VB contact) (NP (DT the) (NN NMCC) (S (VP (TO to) (VP (VB request) (NP (DT a) (NN fighter) (NN escort))))))))) (. .)))
FFA headquarters did not contact the NMCC because they felt it was unnecessary. 
( ( FFA headquarters ) ( ( ( did not ) ( ( contact ( the NMCC ) ) ( because ( they ( felt ( it ( was unnecessary ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP FFA) (NNS headquarters)) (VP (VBD did) (RB not) (VP (VB contact) (NP (DT the) (NN NMCC)) (SBAR (IN because) (S (NP (PRP they)) (VP (VBD felt) (SBAR (S (NP (PRP it)) (VP (VBD was) (ADJP (JJ unnecessary)))))))))) (. .)))