▁Duke ▁of ▁York ▁( as ▁he ▁was ▁by ▁then ) ▁transferred ▁to ▁the ▁General ▁List , ▁en rolled ▁in ▁a ▁four - month ▁hel ic opter ▁war fare ▁instruct or ' s ▁course ▁at ▁R N AS ▁Ye ov il ton , ▁and , ▁upon ▁gradu ation , ▁served ▁from ▁February ▁ 1 9 8 7 ▁to ▁April ▁ 1 9 8 8 ▁as ▁a ▁hel ic opter ▁war fare ▁officer ▁in ▁ 7 0 2 ▁Naval ▁Air ▁Squadron , ▁R N AS ▁Port land . ▁He ▁also ▁served ▁on ▁HMS ▁Edinburgh ▁as ▁an ▁Officer ▁of ▁the ▁Watch ▁and ▁Ass istant ▁N avig ating ▁Officer ▁until ▁ 1 9 8 9 , ▁including ▁a ▁six - month ▁deployment ▁to ▁the ▁Far ▁East ▁as ▁part ▁of ▁exercise ▁Out back ▁ 8 8 . ▁ ▁The ▁Duke ▁of ▁York ▁served ▁as ▁flight ▁commander ▁and ▁pilot ▁of ▁the ▁Lyn x ▁H AS 3 ▁on ▁HMS ▁Camp b elt own ▁from ▁ 1 9 8 9 ▁to ▁ 1 9 9 1 . ▁He ▁also ▁acted ▁as ▁Force ▁A viation ▁Officer ▁to ▁Stand ing ▁NR F ▁Mar itime ▁Group ▁ 1 ▁while ▁Camp b elt own ▁was ▁flags hip ▁of ▁the ▁NAT O ▁force ▁in ▁the ▁North ▁Atlantic ▁from ▁ 1 9 9 0 ▁to ▁ 1 9 9 1 . ▁He ▁passed ▁the ▁squad ron ▁command ▁exam ination ▁on ▁ 1 6 ▁July ▁ 1 9 9 1 , ▁attended ▁the ▁Staff ▁College , ▁Cam ber ley ▁the ▁following ▁year , ▁and ▁completed ▁the ▁Army ▁Staff