(S (S (NP (BASENP (NN Aircraft)) (VP (VBN lost) (PP (IN in) (BASENP (DT this) (NN region))))) (VP (VBP have) (VP (ADVP (RB sometimes)) (VP (ADVP (RB never)) (VP (VBN been) (VP (VBN located) (PP (IN after) (BASENP (JJ suspected) (NNS crashes))))))))) (PERIOD .))