NTSB warned in 2002 that canopies on the boats could trap fish . Records show only two fatal accidents involving amphibious tour boats . 2 were killed in Philadelphia sinking in July ; 13 drowned in 1999 sinking in September . Coast Guard disregarded safety recommendations after 1999 tragedy .
NTSB warned in 2002 that canopies on excursion vessels could trap passengers . Records show only two fatal accidents involving amphibious tour boats . 2 students killed in Philadelphia crash in July ; 13 drowned in 1999 sinking in Arkansas . Coast Guard disregarded NTSB recommendations after 1999 tragedy .