▁Crit ic ism ▁of ▁air space ▁closure ▁There ▁was ▁much ▁criticism ▁by ▁air lines , ▁which ▁suffered ▁large ▁financial ▁losses , ▁of ▁the ▁air space ▁clos ures ▁as ▁unnecessary ; ▁however , ▁the ▁EU ▁transport ▁presiden cy ▁disag re ed , ▁saying ▁that ▁" This ▁situation ▁is ▁causing ▁them ▁important ▁losses , ▁but ▁safety ▁is ▁param ount ". ▁ ▁Military ▁flying ▁Some ▁military ▁aircraft ▁which ▁fle w ▁during ▁the ▁period ▁of ▁closure ▁suffered ▁engine ▁damage , ▁although ▁no ▁crashes ▁were ▁reported . ▁ ▁On ▁ 1 5 ▁April , ▁five ▁Finn ish ▁Air ▁Force ▁F - 1 8 ▁f ighter ▁j ets ▁on ▁exercise ▁fle w ▁into ▁the ▁ash ▁cloud ▁in ▁northern ▁Finland . ▁Vol can ic ▁dust ▁was ▁found ▁on ▁the ▁engines ▁of ▁three ▁of ▁the ▁aircraft ▁and ▁a ▁further ▁ins pection ▁revealed ▁extensive ▁damage ▁by ▁mol ten ▁glass ▁depos its ▁inside ▁the ▁comb ust ion ▁chamber ▁of ▁one ▁of ▁the ▁engines . ▁The ▁engines ▁were ▁sent ▁for ▁dis assembly ▁and ▁over ha ul . ▁As ▁a ▁result , ▁all ▁unnecessary ▁military ▁fl ights ▁were ▁cancel led ▁except ▁for ▁identification ▁fl ights ▁to ▁en force ▁so ver eign ▁air space . ▁Meanwhile , ▁a ▁B AE ▁Haw k ▁tra iner ▁with ▁special ▁equipment ▁to ▁sample ▁the ▁vol can ic ▁dust ▁was ▁being ▁flow n ▁from ▁the ▁ 4 1 st ▁squad ron ▁in ▁K au h ava . ▁Even ▁short ▁test ▁fl ights ▁with ▁an ▁F - 1 8 ▁revealed ▁engine ▁damage ▁sufficient ▁to ▁destroy ▁engines . ▁ ▁On ▁ 1 9