FAA headquarters had by this time established an open line of communication with the Command Center at Herndon and instructed it to poll all its centers about suspect aircraft.
( ( FAA headquarters ) ( ( ( had ( by ( this time ) ) ) ( ( ( ( ( established ( ( an ( open line ) ) ( of communication ) ) ) ( with ( the ( Command Center ) ) ) ) ( at Herndon ) ) and ) ( instructed ( it ( to ( ( poll ( all ( its centers ) ) ) ( about ( suspect aircraft ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP FAA) (NNS headquarters)) (VP (VBD had) (PP (IN by) (NP (DT this) (NN time))) (VP (VP (VBN established) (NP (NP (DT an) (JJ open) (NN line)) (PP (IN of) (NP (NN communication)))) (PP (IN with) (NP (DT the) (NNP Command) (NNP Center))) (PP (IN at) (NP (NNP Herndon)))) (CC and) (VP (VBN instructed) (S (NP (PRP it)) (VP (TO to) (VP (VB poll) (NP (PDT all) (PRP$ its) (NNS centers)) (PP (IN about) (NP (NN suspect) (NN aircraft))))))))) (. .)))
The Herndon Command Center was told to ask about suspect aircraft at all centers belonging to it.
( ( The ( Herndon ( Command Center ) ) ) ( ( was ( told ( to ( ( ask ( ( about suspect ) aircraft ) ) ( at ( ( all centers ) ( belonging ( to it ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NNP Herndon) (NNP Command) (NNP Center)) (VP (VBD was) (VP (VBN told) (S (VP (TO to) (VP (VB ask) (NP (ADJP (RB about) (JJ suspect)) (NN aircraft)) (PP (IN at) (NP (NP (DT all) (NNS centers)) (VP (VBG belonging) (PP (TO to) (NP (PRP it))))))))))) (. .)))