(S (S (SBAR (IN While) (S (BASENP (NNS pilots)) (VP (VBD were) (VP (VBG troubleshooting) (PP (IN for) (BASENP (DT this) (JJ navigational) (NN system))))))) (S (BASENP (PRP they)) (VP (VP (ADVP (RB first)) (VP (ADVP (RB unintentionally)) (VP (VBD disconnected) (BASENP (DT the) (NN autopilot))))) (COMMA ,) (VP (ADVP (RB then)) (VP (VBD failed) (S (VP (TO to) (VP (VP (VB monitor) (NP (BASENP (JJ other) (NNS instruments)) (VP (VP (VBG informing) (BASENP (PRP them))) (SBAR (S (BASENP (PRP they)) (VP (VBD were) (VP (VBG approaching) (BASENP (DT the) (NN sea))))))))) (COMMA ,) (S (VP (VP (VBG crashing) (PP (IN into) (BASENP (PRP it)))) (CC and) (VP (VBG destroying) (BASENP (DT the) (NN aircraft))))))))))))) (PERIOD .))