(S (S (BASENP (DT The) (NNP AAIB)) (VP (ADVP (RB further)) (VP (VP (VBD noted) (SBAR (IN that) (S (BASENP (PRP it)) (VP (VP (VBZ is) (ADJP (JJ unclear))) (SBAR (IN whether) (S (BASENP (JJ other) (NN aircraft) (NNS designs)) (VP (VBP are) (PP (IN at) (BASENP (NN risk)))))))))) (CONJP (COMMA ,) (CC and)) (VP (VP (VBD advised) (BASENP (DT the) (NNP FAA) (CC and) (NNP EASA))) (S (VP (TO to) (VP (VP (VB look) (PP (IN into) (NP (BASENP (JJ increased) (NN use)) (PP (IN of) (BASENP (NN de-icing) (NNS additives)))))) (CC and) (VP (VB investigate) (NP (CC both) (NP (NP (NP (NP (DT the) (NP (BASENP (NN accumulation)) (CC and) (BASENP (JJ sudden) (NN movement)))) (PP (IN of) (BASENP (NN ice)))) (PP (IN in) (BASENP (NN aircraft) (NN fuel) (NNS systems)))) (CC and) (NP (NP (BASENP (DT the) (JJ actual) (NN formation)) (PP (IN of) (BASENP (NN ice)))) (PP (IN in) (NP (BASENP (DT the) (NN fuel)) (BASENP (PRP itself))))))))))))))) (PERIOD .))