▁and ▁cleared ▁at ▁. ▁By ▁the ▁time ▁the ▁first ▁wave ▁of ▁North ▁Vietnam ese ▁Mi G ▁f igh ters ▁had ▁taken ▁off , ▁two ▁additional ▁fl ights ▁of ▁F - 4 C ▁f igh ters ▁from ▁the ▁ 8 th ▁T F W ▁had ▁already ▁flow n ▁into ▁the ▁area ▁und et ected . ▁Due ▁to ▁their ▁lack ▁of ▁rad ar ▁equipment , ▁North ▁Vietnam ese ▁Mi G - 1 7 ▁f igh ters ▁were ▁restricted ▁to ▁flying ▁at ▁cloud ▁base , ▁so ▁they ▁failed ▁to ▁detect ▁the ▁presence ▁of ▁U . S . ▁f igh ters ▁that ▁were ▁flying ▁at ▁a ▁higher ▁alt itude . ▁ ▁From ▁above ▁ ▁U . S . ▁F - 4 ▁f igh ters ▁had ▁a ▁greater ▁energy ▁level ▁over ▁North ▁Vietnam ese ▁Mi G - 1 7 ▁and ▁Mi G - 2 1 ▁f igh ters , ▁and ▁U . S . ▁pil ots ▁had ▁no ▁trouble ▁seeing ▁or ▁ident ifying ▁North ▁Vietnam ese ▁f igh ters ▁flying ▁up ▁from ▁below . ▁Furthermore , ▁weather ▁conditions ▁on ▁the ▁day ▁allowed ▁rad ar ▁and ▁miss ile ▁systems ▁on ▁the ▁F - 4 ▁f igh ters ▁to ▁perform ▁at ▁their ▁maximum ▁level , ▁an ▁advantage ▁which ▁U . S . ▁pil ots ▁fully ▁explo ited ▁as ▁North ▁Vietnam ese ▁Mi G ▁f igh ters ▁fle w ▁up ▁to ▁eng age ▁them . ▁Just ▁after ▁ 3 : 0 0   pm ▁North ▁Vietnam ese ▁Mi G - 2 1 ▁f igh ters ▁appeared ▁through ▁the ▁clouds ▁and ▁began