At that point in time, the Langley pilots did not know the threat they were facing, did not know where United 93 was located, and did not have shootdown authorization.
( ( At ( ( that point ) ( in time ) ) ) ( , ( ( the ( Langley pilots ) ) ( ( ( ( ( ( ( ( did not ) ( know ( ( the threat ) ( they ( were facing ) ) ) ) ) , ) ( ( did not ) ( know ( where ( ( United 93 ) ( was located ) ) ) ) ) ) , ) and ) ( ( did not ) ( have ( shootdown authorization ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN At) (NP (NP (DT that) (NN point)) (PP (IN in) (NP (NN time))))) (, ,) (NP (DT the) (NNP Langley) (NNS pilots)) (VP (VP (VBD did) (RB not) (VP (VB know) (NP (NP (DT the) (NN threat)) (SBAR (S (NP (PRP they)) (VP (VBD were) (VP (VBG facing)))))))) (, ,) (VP (VBD did) (RB not) (VP (VB know) (SBAR (WHADVP (WRB where)) (S (NP (NNP United) (CD 93)) (VP (VBD was) (VP (VBN located))))))) (, ,) (CC and) (VP (VBD did) (RB not) (VP (VB have) (NP (NN shootdown) (NN authorization))))) (. .)))
Without proper knowledge of the situation and authorization the Langley pilots really could not do anything to help.
( ( Without ( ( proper knowledge ) ( of ( the ( ( situation and ) authorization ) ) ) ) ) ( ( the ( Langley pilots ) ) ( really ( ( ( could not ) ( do ( ( anything to ) help ) ) ) . ) ) ) )
(ROOT (S (PP (IN Without) (NP (NP (JJ proper) (NN knowledge)) (PP (IN of) (NP (DT the) (NN situation) (CC and) (NN authorization))))) (NP (DT the) (NNP Langley) (NNS pilots)) (ADVP (RB really)) (VP (MD could) (RB not) (VP (VB do) (NP (NN anything) (TO to) (VB help)))) (. .)))