At 9:03, they would see another aircraft strike the World Trade Center.
( ( At 9:03 ) ( , ( they ( ( would ( see ( ( another aircraft ) ( strike ( the ( World ( Trade Center ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN At) (NP (CD 9:03))) (, ,) (NP (PRP they)) (VP (MD would) (VP (VB see) (S (NP (DT another) (NN aircraft)) (VP (VB strike) (NP (DT the) (NNP World) (NNP Trade) (NNP Center)))))) (. .)))
The other plane was making a peaceful descent onto the runway.
( ( The ( other plane ) ) ( ( was ( ( making ( a ( peaceful descent ) ) ) ( onto ( the runway ) ) ) ) . ) )
(ROOT (S (NP (DT The) (JJ other) (NN plane)) (VP (VBD was) (VP (VBG making) (NP (DT a) (JJ peaceful) (NN descent)) (PP (IN onto) (NP (DT the) (NN runway))))) (. .)))