To avoid New York area air traffic and uncertain about what to do, the fighters were brought down to military airspace to hold as needed.
( ( To ( avoid ( ( New York ) ( ( ( area ( air ( ( traffic and ) uncertain ) ) ) ( about what ) ) ( to do ) ) ) ) ) ( , ( ( the fighters ) ( ( were ( ( ( brought down ) ( to ( military airspace ) ) ) ( to ( hold ( as needed ) ) ) ) ) . ) ) ) )
(ROOT (S (S (VP (TO To) (VP (VB avoid) (NP (NP (NNP New) (NNP York)) (SBAR (WHNP (NP (NN area) (NN air) (NN traffic) (CC and) (NN uncertain)) (WHPP (IN about) (WHNP (WP what)))) (S (VP (TO to) (VP (VB do))))))))) (, ,) (NP (DT the) (NNS fighters)) (VP (VBD were) (VP (VBN brought) (PRT (RP down)) (PP (TO to) (NP (JJ military) (NN airspace))) (S (VP (TO to) (VP (VB hold) (ADJP (RB as) (VBN needed))))))) (. .)))
They didn't try to avoid air traffic at all. 
( They ( ( ( did n't ) ( try ( to ( ( avoid ( air traffic ) ) ( at all ) ) ) ) ) . ) )
(ROOT (S (NP (PRP They)) (VP (VBD did) (RB n't) (VP (VB try) (S (VP (TO to) (VP (VB avoid) (NP (NN air) (NN traffic)) (ADVP (IN at) (DT all))))))) (. .)))