At 8:23, the dispatcher tried unsuccessfully to contact the aircraft.
( ( At 8:23 ) ( , ( ( the dispatcher ) ( ( ( tried unsuccessfully ) ( to ( contact ( the aircraft ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN At) (NP (CD 8:23))) (, ,) (NP (DT the) (NN dispatcher)) (VP (VBD tried) (ADVP (RB unsuccessfully)) (S (VP (TO to) (VP (VB contact) (NP (DT the) (NN aircraft)))))) (. .)))
The dispatcher couldn't contact the aircraft around 8:23.
( ( The dispatcher ) ( ( ( could n't ) ( ( contact ( the aircraft ) ) ( around 8:23 ) ) ) . ) )
(ROOT (S (NP (DT The) (NN dispatcher)) (VP (MD could) (RB n't) (VP (VB contact) (NP (DT the) (NN aircraft)) (PP (IN around) (NP (CD 8:23))))) (. .)))