He tried the radios, first calling the aircraft directly, then the airline.
( He ( ( ( ( tried ( the radios ) ) , ) ( first ( calling ( ( ( ( the aircraft ) directly ) , ) ( then ( the airline ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP He)) (VP (VBD tried) (NP (DT the) (NNS radios)) (, ,) (S (ADVP (RB first)) (VP (VBG calling) (S (S (NP (DT the) (NN aircraft)) (ADVP (RB directly))) (, ,) (S (ADVP (RB then)) (NP (DT the) (NN airline))))))) (. .)))
He tried talking to the pilot, then he contacted the airline.
( ( ( ( ( He ( tried ( talking ( to ( the pilot ) ) ) ) ) , ) then ) ( he ( contacted ( the airline ) ) ) ) . )
(ROOT (S (S (NP (PRP He)) (VP (VBD tried) (S (VP (VBG talking) (PP (TO to) (NP (DT the) (NN pilot))))))) (, ,) (RB then) (S (NP (PRP he)) (VP (VBD contacted) (NP (DT the) (NN airline)))) (. .)))