5 5 th ▁and ▁ 3 8 8 th ▁T act ical ▁F ighter ▁W ings ▁based ▁in ▁Th ailand , ▁for ▁the ▁second ▁attack ▁on ▁Y en ▁Vien . ▁The ▁ 5 5 5 th ▁T act ical ▁F ighter ▁Squadron ▁provided ▁two ▁fl ights ▁of ▁F - 4 ▁Ph ant oms , ▁' F ord ' ▁flight ▁and ▁' F al con ' ▁flight . ▁The ▁mission ▁was ▁led ▁by ▁Colonel ▁Nicholas ▁J . ▁Don el son ▁with ▁Old s , ▁who ▁spe ar head ed ▁Operation ▁B olo ▁back ▁in ▁January , ▁as ▁the ▁leader ▁of ▁the ▁esc ort ▁formation . ▁At ▁ 1 : 4 5   pm ▁on ▁ 2 3 ▁August , ▁North ▁Vietnam ese ▁rad ars ▁detected ▁a ▁flight ▁of ▁ 4 0 ▁U . S ▁aircraft ▁approaching ▁H ano i ▁from ▁Sam ▁Ne ua , ▁in ▁neighbor ing ▁La os . ▁ ▁The ▁V P AF ▁High ▁Command ▁immediately ▁sc ram bled ▁two ▁fl ights ▁of ▁four ▁Mi G - 1 7 ▁f igh ters ▁from ▁the ▁V P AF ▁ 9 2 3 rd ▁F ighter ▁Regiment , ▁followed ▁by ▁two ▁Mi G - 2 1 ▁f igh ters ▁from ▁the ▁V P AF ▁ 9 2 1 st ▁F ighter ▁Regiment ▁at ▁ 2 : 5 1   pm . ▁The ▁Mi G - 2 1 ▁force ▁was ▁led ▁by ▁N gu yen ▁N hat ▁Ch ieu ▁with ▁N gu yen ▁Van ▁C oc , ▁who ▁had ▁participated ▁in ▁the ▁V P AF