Radar reconstructions performed after 9/11 reveal that FAA radar equipment tracked the flight from the moment its transponder was turned off at 8:56.
( ( ( Radar reconstructions ) ( performed ( after 9/11 ) ) ) ( ( reveal ( that ( ( FAA ( radar equipment ) ) ( ( tracked ( the flight ) ) ( from ( ( the moment ) ( ( its transponder ) ( was ( ( turned off ) ( at 8:56 ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (JJ Radar) (NNS reconstructions)) (VP (VBN performed) (PP (IN after) (NP (CD 9/11))))) (VP (VBP reveal) (SBAR (IN that) (S (NP (NNP FAA) (NN radar) (NN equipment)) (VP (VBD tracked) (NP (DT the) (NN flight)) (PP (IN from) (NP (NP (DT the) (NN moment)) (SBAR (S (NP (PRP$ its) (NN transponder)) (VP (VBD was) (VP (VBN turned) (PRT (RP off)) (PP (IN at) (NP (CD 8:56))))))))))))) (. .)))
9/11 could have been avoided if actions against the tracked flight were taken.
( 9/11 ( ( could ( have ( been ( avoided ( if ( ( actions ( against ( the ( tracked flight ) ) ) ) ( were taken ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (CD 9/11)) (VP (MD could) (VP (VB have) (VP (VBN been) (VP (VBN avoided) (SBAR (IN if) (S (NP (NP (NNS actions)) (PP (IN against) (NP (DT the) (JJ tracked) (NN flight)))) (VP (VBD were) (VP (VBN taken))))))))) (. .)))