The flight did not respond.
( ( The flight ) ( ( ( did not ) respond ) . ) )
(ROOT (S (NP (DT The) (NN flight)) (VP (VBD did) (RB not) (VP (VB respond))) (. .)))
The flight responded.  
( ( The flight ) ( responded . ) )
(ROOT (S (NP (DT The) (NN flight)) (VP (VBD responded)) (. .)))