At 9:03:11, United Airlines Flight 175 struck the South Tower of the World Trade Center.
( ( At 9:03:11 ) ( , ( ( United ( Airlines ( Flight 175 ) ) ) ( ( struck ( ( the ( South Tower ) ) ( of ( the ( World ( Trade Center ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN At) (NP (CD 9:03:11))) (, ,) (NP (NNP United) (NNP Airlines) (NNP Flight) (CD 175)) (VP (VBD struck) (NP (NP (DT the) (NNP South) (NNP Tower)) (PP (IN of) (NP (DT the) (NNP World) (NNP Trade) (NNP Center))))) (. .)))
United Airlines Flight 175 increased its speed as it struck the South Tower.
( ( United ( Airlines ( Flight 175 ) ) ) ( ( ( increased ( its speed ) ) ( as ( it ( struck ( the ( South Tower ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP United) (NNP Airlines) (NNP Flight) (CD 175)) (VP (VBD increased) (NP (PRP$ its) (NN speed)) (SBAR (IN as) (S (NP (PRP it)) (VP (VBD struck) (NP (DT the) (NNP South) (NNP Tower)))))) (. .)))