Many controllers work at the FAA's 22 Air Route Traffic Control Centers.
( ( ( Many ( controllers work ) ) ( at ( the FAA ) ) ) ( ( 's ( 22 ( Air ( Route ( Traffic ( Control Centers ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (JJ Many) (NNS controllers) (NN work)) (PP (IN at) (NP (DT the) (NNP FAA)))) (VP (VBZ 's) (NP (CD 22) (NNP Air) (NNP Route) (NNP Traffic) (NNP Control) (NNPS Centers))) (. .)))
Many controllers work in the control centers and they all had to hear the events that day.
( ( ( ( ( Many controllers ) ( work ( in ( the ( control centers ) ) ) ) ) and ) ( they ( all ( had ( to ( hear ( ( the events ) ( that day ) ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (JJ Many) (NNS controllers)) (VP (VBP work) (PP (IN in) (NP (DT the) (NN control) (NNS centers))))) (CC and) (S (NP (PRP they)) (ADVP (DT all)) (VP (VBD had) (S (VP (TO to) (VP (VB hear) (NP (NP (DT the) (NNS events)) (NP (DT that) (NN day)))))))) (. .)))