 During the Vietnam War , the F @-@ 4 was used extensively ; it served as the principal air superiority fighter for both the Navy and Air Force , and became important in the ground @-@ attack and aerial reconnaissance roles late in the war . The Phantom has the distinction of being the last U.S. fighter flown to attain ace status in the 20th century . During the Vietnam War , the U.S. Air Force had one pilot and two weapon systems officers ( <unk> ) , and the US Navy had one pilot and one radar intercept officer ( RIO ) become aces by achieving five aerial kills against enemy fighter aircraft . The F @-@ 4 continued to form a major part of U.S. military air power throughout the 1970s and 1980s , being gradually replaced by more modern aircraft such as the F @-@ 15 Eagle and F @-@ 16 in the U.S. Air Force , the Grumman F @-@ 14 Tomcat in the U.S. Navy , and the F / A @-@ 18 Hornet in the U.S. Navy and U.S. Marine Corps . 
