(S (S (S (BASENP (PRP They)) (VP (VBD were) (VP (VP (VBN scrambled) (PP (IN from) (BASENP (NNP Quebec)))) (S (VP (TO to) (VP (VP (VB escort) (NP (BASENP (DT the) (JJ inter-continental) (NN flight)) (VP (VBG originating) (PP (IN from) (BASENP (NNP London)))))) (PP (TO to) (BASENP (DT the) (NNP Halifax) (NNP International) (NNP Airport))))))))) (SBAR (IN after) (S (NP (BASENP (DT a) (NN hijacking) (NN signal)) (PRN (COMMA ,) (BASENP (DT an) (JJ apparent) (NN accident)) (COMMA ,))) (VP (VBD was) (VP (VBN sent) (PP (IN from) (BASENP (DT the) (NN plane)))))))) (PERIOD .))