The controller only heard something unintelligible; he did not hear the specific words we have some planes.
( ( ( ( ( The controller ) ( only ( heard ( something unintelligible ) ) ) ) ; ) ( he ( ( did not ) ( hear ( ( the ( specific words ) ) ( we ( have ( some planes ) ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (DT The) (NN controller)) (ADVP (RB only)) (VP (VBD heard) (NP (NN something) (NN unintelligible)))) (: ;) (S (NP (PRP he)) (VP (VBD did) (RB not) (VP (VB hear) (NP (NP (DT the) (JJ specific) (NNS words)) (SBAR (S (NP (PRP we)) (VP (VBP have) (NP (DT some) (NNS planes))))))))) (. .)))
The controller was eventually able to decipher the words.
( ( The controller ) ( ( ( was eventually ) ( able ( to ( decipher ( the words ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN controller)) (VP (VBD was) (ADVP (RB eventually)) (ADJP (JJ able) (S (VP (TO to) (VP (VB decipher) (NP (DT the) (NNS words))))))) (. .)))