John Heilig was born in 1940 in Miami, Florida. He entered the Naval Aviation Cadet program on March 2, 1961, and entered flight training in September 1961, earning his designation as a Naval Aviator in April 1963. Ens Heilig next attended the Officers Photo Reconnaissance Course at NAS Pensacola, Florida, from May to July 1963, followed by F-8 Crusader Replacement Air Group training with VF-124 at NAS Miramar, California, from July to October 1963. He served as an RF-8A pilot with VFP-163 from October 1963 until he was forced to eject over North Vietnam and was taken as a Prisoner of War on May 5, 1966. During this time he flew missions in Southeast Asia aboard the aircraft carrier USS Constellation (CVA-64) from June to November 1964, and aboard the aircraft carrier USS Hancock (CVA-19) from January 1966 until he was shot down in May 1966. After spending 2,476 days in captivity, LCDR Heilig was released during Operation Homecoming on February 12, 1973. He was briefly hospitalized to recover from his injuries at the Naval Hospital in Jacksonville, Florida, and then received an assignment to complete his bachelor's degree at the University of Miami, Florida, from December 1973 to December 1975. His next assignment was as an instructor pilot and Executive Officer with VT-10 at NAS Pensacola from January 1976 to February 1979, followed by amphibious training at Naval Amphibious Base Little Creek, Virginia, in February 1979. CDR Heilig served as Executive Officer of VT-4 at NAS Pensacola from March 1979 to June 1980, and then as Commanding Officer of Training Air Wing SIX at NAS Pensacola from June 1980 to August 1981. He attended the National War College at Fort McNair, Washington, D.C., from August 1981 to June 1982, and then served as Assistant Air Officer aboard the aircraft carrier USS Lexington (AVT-16) from August 1982 to December 1984. Capt Heilig next served as Assistant Chief of Staff for International Naval Education on the staff of the Chief of Naval Education and Training at NAS Pensacola from January 1985 to June 1986, followed by service as Commanding Officer of the Naval Education and Training Security Assistance Field Activity at NAS Pensacola from June 1986 to November 1988. He served as Commanding Officer of NAS Kingsville, Texas, from June 1989 to June 1991, and then as Officer in Charge of two training detachments supporting Royal Saudi Naval Forces Undergraduate Helicopter Flight Training from July 1991 until his retirement from the Navy on October 1, 1992.

His Silver Star Citation reads:

For conspicuous gallantry and intrepidity while interned as a Prisoner of War in North Vietnam. In November 1966, his captors, completely ignoring international agreements, subjected him to extreme mental and physical cruelties in an attempt to obtain military information and false confessions for propaganda purposes. Through his resistance to those brutalities, he contributed significantly toward the eventual abandonment of harsh treatment by the North Vietnamese, which was attracting international attention. By his determination, courage, resourcefulness, and devotion to duty, he reflected great credit upon himself and upheld the highest traditions of the Naval Service and the United States Armed Forces.