At the same time or shortly thereafter, Atta-the only terrorist on board trained to fly a jet-would have moved to the cockpit from his business-class seat, possibly accompanied by Omari.
( ( At ( ( the ( same time ) ) ( or ( shortly thereafter ) ) ) ) ( , ( ( ( Atta-the ( only terrorist ) ) ( on ( board ( trained ( to ( fly ( a jet-would ) ) ) ) ) ) ) ( ( have ( ( moved ( to ( the cockpit ) ) ) ( from ( ( ( his ( business-class seat ) ) , ) ( possibly ( accompanied ( by Omari ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN At) (UCP (NP (DT the) (JJ same) (NN time)) (CC or) (ADVP (RB shortly)) (ADVP (RB thereafter)))) (, ,) (NP (NP (JJ Atta-the) (JJ only) (NN terrorist)) (PP (IN on) (NP (NP (NN board)) (VP (VBN trained) (S (VP (TO to) (VP (VB fly) (NP (DT a) (NN jet-would))))))))) (VP (VBP have) (VP (VBN moved) (PP (TO to) (NP (DT the) (NN cockpit))) (PP (IN from) (NP (NP (PRP$ his) (ADJP (JJ business-class)) (NN seat)) (, ,) (VP (ADVP (RB possibly)) (VBN accompanied) (PP (IN by) (NP (NNP Omari)))))))) (. .)))
There were no terrorists who had any idea how to fly an airplane.
( There ( ( were ( ( no terrorists ) ( who ( ( had ( any idea ) ) ( how ( to ( fly ( an airplane ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (EX There)) (VP (VBD were) (NP (NP (DT no) (NNS terrorists)) (SBAR (WHNP (WP who)) (S (VP (VBD had) (NP (DT any) (NN idea)) (SBAR (WHADVP (WRB how)) (S (VP (TO to) (VP (VB fly) (NP (DT an) (NN airplane))))))))))) (. .)))