(S (S (PP (IN On) (BASENP (NNP Thursday))) (COMMA ,) (S (NP (BASENP (NN air) (NN traffic)) (PP (IN in) (BASENP (DT the) (JJ whole) (NN country)))) (VP (VBD was) (VP (VBN limited) (PP (JJ due) (PP (TO to) (NP (BASENP (NN ash) (NNS layers)) (PP (IN on) (BASENP (JJ several) (NNS airports)))))))))) (PERIOD .))