The most recent hijacking that involved U.S. air traffic controllers, FAA management, and military coordination had occurred in 1993.
( ( ( The ( most ( recent hijacking ) ) ) ( that ( involved ( ( ( ( ( ( U.S. ( air ( traffic controllers ) ) ) , ) ( FAA management ) ) , ) and ) ( military coordination ) ) ) ) ) ( ( had ( occurred ( in 1993 ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (RBS most) (JJ recent) (NN hijacking)) (SBAR (WHNP (WDT that)) (S (VP (VBD involved) (NP (NP (NNP U.S.) (NN air) (NN traffic) (NNS controllers)) (, ,) (NP (NNP FAA) (NN management)) (, ,) (CC and) (NP (JJ military) (NN coordination))))))) (VP (VBD had) (VP (VBN occurred) (PP (IN in) (NP (CD 1993))))) (. .)))
The last hijacking that involved military coordination had been in May of 1993.
( ( ( The ( last hijacking ) ) ( that ( involved ( military coordination ) ) ) ) ( ( had ( been ( in ( May ( of 1993 ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (JJ last) (NN hijacking)) (SBAR (WHNP (WDT that)) (S (VP (VBD involved) (NP (JJ military) (NN coordination)))))) (VP (VBD had) (VP (VBN been) (PP (IN in) (NP (NP (NNP May)) (PP (IN of) (NP (CD 1993))))))) (. .)))