Seely was on six combat tours in Vietnam. His first tour was from March to June 1966 when he flew fifty-nine combat missions from the USS Enterprise (CVN-65). His second tour was from January to June 1967 where he flew eight-nine combat missions from the USS Hancock (CVA-19). His third tour was from the USS Bon Homme Richard (CVA-31) from January to April 1968 where he flew fifty-six combat missions, some of which were to support the marines at Khe Sanh. He was on the USS Shangri-La (CVA-38) from March to December 1970 for his fourth tour where he flew ninety-seven combat missions. He was on the USS Constellation (CVA-64) for his fifth and sixth tours. His fifth tour, from October 1971 to June 1972 was his longest and he flew one hundred thirty-five combat missions, including missions in support of Operation Linebacker I. His sixth tour lasted from January to June in 1973 and he flew eleven missions.