Jarrah, like Atta earlier, may have inadvertently broadcast the message because he did not know how to operate the radio and the intercom.
( Jarrah ( , ( ( like ( Atta earlier ) ) ( , ( ( may ( have ( inadvertently ( ( broadcast ( the message ) ) ( because ( he ( ( did not ) ( know ( how ( to ( operate ( ( ( the radio ) and ) ( the intercom ) ) ) ) ) ) ) ) ) ) ) ) ) . ) ) ) ) )
(ROOT (S (NP (NNP Jarrah)) (, ,) (PP (IN like) (ADVP (NP (NNP Atta)) (RBR earlier))) (, ,) (VP (MD may) (VP (VB have) (VP (ADVP (RB inadvertently)) (VBN broadcast) (NP (DT the) (NN message)) (SBAR (IN because) (S (NP (PRP he)) (VP (VBD did) (RB not) (VP (VB know) (SBAR (WHADVP (WRB how)) (S (VP (TO to) (VP (VB operate) (NP (NP (DT the) (NN radio)) (CC and) (NP (DT the) (NN intercom)))))))))))))) (. .)))
As Atta had previously done, Jarrah may have accidentally sent his message.
( ( As ( Atta ( ( had previously ) done ) ) ) ( , ( Jarrah ( ( may ( have ( accidentally ( sent ( his message ) ) ) ) ) . ) ) ) )
(ROOT (S (SBAR (IN As) (S (NP (NNP Atta)) (VP (VBD had) (ADVP (RB previously)) (VP (VBN done))))) (, ,) (NP (NNP Jarrah)) (VP (MD may) (VP (VB have) (VP (ADVP (RB accidentally)) (VBN sent) (NP (PRP$ his) (NN message))))) (. .)))