The F-4D joined combat forces in Southeast Asia in May 1967. The F-4D relegated most of the F-4Cs to the ground attack role while the F-4Ds were tasked with air to air interception duties. In addition to the AIM-7 Sparrow and AIM-9 Sidewinder, the F-4D was also capable of firing the Falcon missile. The Falson missile proved to be a failure, and after a brief trial period it was withdrawn from Vietnam combat service. The F-4 proved its worth in combat 05 June 1967, when a crew from the 555th Tactical Fighter Squadron downed a MiG-17 with an AIM-7 Sparrow missile. F-4Ds were the first aircraft to use laser guided munitions carrying GBU-1O/B Mk 84 Laser guided bombs in May 1968. USAF F-4s also flew reconnaissance and "Wild Weasel" anti-aircraft missile suppression missions.
Lieutenant Colonel "Steve" Ritchie was the US Air Force's only pilot ace of the Vietnam War. On 10 May 1972, Ritchie was flying an F-4D with his Weapon System Officer, Captain Chuck DeBellevue, when they destroyed their first MiG-21 with a radar-guided Sparrow missile. This initial success was achieved while flying fighter cover (MIGCAP) for a 32-plane strike force targeted against the Paul Doumer Bridge and the Yen Vien Railroad yard. Following another victory at the end of May, he achieved a double kill in July while leading a 4-ship of Phantoms to protect a large strike force as it egressed the target area near Hanoi. "Steve" Ritchie downed his fifth MiG on 28 August 1972, making him the only American pilot to down five MiG-21s--North Vietnam's most sophisticated fighter aircraft. After returning from Southeast Asia, he received the MacKay Trophy for the "most significant Air Force mission of 1972."
The F-4D boasted several new features including an improved bombing capability by supplying radar slant range to the bombing computer, better air to air range from a stabilized lead computing gunsight, redesigned equipment cooling system and number 1 fuel cell. From the start, F-4Ds featured AIM-4D Falcon infrared air to air missiles
The Navy procured the F-4D for the Air Force as it had the F-4C. Purchase of the first 52 F-4Ds, funded by Congress in fiscal year 1964, was initiated by a March 1964 letter contract. Procurement ended 2 years later in favor of the subsequent F- 4E. Navy fixed price contract (N00019-67-Cr0095), definitized in August 1966, covered both the last F-4Ds (funded in fiscal year 1966) and the first F-4Es.
The Air Force accepted the aircraft in December 1965.
Category I flight testing occurred from June 1965-March 1966; Category II, March 1966-October 1966. To save time, the 8 month Category II testing also evaluated the F-4D under simulated combat conditions. This eliminated formal Category III tests.
The F-4D entered operational service in April 1966.
TAC assigned its first 16 F-4Ds to the Fighter Weapons School at Nellis AFB. It was 21 June before the aircraft reached a combat unit (the 33d TFW at Eglin).
The nonavailability of certain components and incomplete testing of others slowed the beginning of F-4D production. Early deliveries lacked multiple and triple ejection racks and carried deficient fire control systems, weapon release computers, and ECM equipment. Limited space to house these items posed another problem.
The F-4D, like many SEA bound fighters, required special equipment. It urgently needed a RHAW system. Moreover, some F-4Ds also had to be modified for Combat Eagle and Wild Weasel duty. Modifications lagged from the outset. Combat Eagle was delayed almost a year, because no new Walleye missiles were available. Wild Weasel fared no better, due to time consuming difficulties in installing the new APS-107 radar in the RHAW system. Furthermore, new problems arose once the aircraft arrived overseas.
In spite of modification slippages, an initial F-4D contingent reached Southeast Asia on schedule. The 555th TFS at Ubon received the first of these aircraft. Other Thailand stationed F-4C squadrons exchanged their aircraft in October and were combat ready in late November. In January 1988, three F-4C squadrons at Da Nang were also re-equipped.
The sophisticated APS-107 radar of RHAW equipped F-4Ds promised greater accuracy than the APR-25/26 system of other RHAW fighters. It was also due to work with Navy developed AGM-78A and B standard antiradiation missiles (SARMs). Yet, the APS-107s operational debut in SEA proved unreliable and erratic. The Walleye, pioneered by the F-4D in August 196?, was likewise a disappointment at first. The aircraft itself had problems, having retained most of the F-4C's deficiencies.
Production ended in February 1968 with With Air Force acceptance of 7 F-4Ds, the last 3 of which reached TAC in April.
A total of 793 F-4Ds were accepted-excluding 32 accepted by the Air Force for the FMS program.
Sixty eight F-4Ds were accepted in FY 66, 519 in FY 67,31 and 206 in FY 68.
The F-4D had a Flyaway Cost Per Production Aircraft of $1.7 million-airframe, $1,018,682; engines (installed), $260,563; electronics, $262,101; ordnance, $6,817; armament, $133,430.
As a war rushed product (almost 800 aircraft built in less than 2 years), the F-4D proved successful. Nonetheless, it bore many F-4C failings and received similar modifications. As forerunner to the F-4E (ordered in mid 1966), the F-4D benefited from Rivet Haste, Pave Spike, and several other E modifications. The F-4E in turn shared some D improvements.
The most significant improvements came during the second half of 1969. In July, 90 F-4Ds were programmed for the new Wild Weasel APR-38 advanced avionics system. The first D fitted with the new system flew on 27 November 1972. Again, as early as November 1969 a LC to Philco Ford started Project Pave Knife. It put a removable pod mounted laser designator on 6 F-4Ds. The first 3 of them (with support equipment and personnel) arrived at Ubon during March 1971. Immediate combat evaluation proved Pave Knife's worth. Although no additional pods were procured, 6 other F-4Ds were given the Pave Knife configuration. Moreover, in early 1972 all 12 planes enjoyed low light level television and better laser warmup. A third decision in December 1969 expanded the number of F-4Ds featuring the long range navigation weapon delivery system. Moreover, these planes were further enhanced by mid 1971. Another key decision in late 1969 proved difficult to carry out. For better acquisition, lock on, and launch of electrooptical weapons, the Air Force wanted scan converter television displays put on 344 F-4Ds. The Air Force also wanted an October 1971 IOC. In handling this $15 million modification project, Hazeltine (the contracting company) faced technical difficulties from the start and could not deliver qualified scan converters on schedule. Yet, by the end of 1972 after the number of F-4Ds involved had been cut to 285 the project appeared to be getting off the ground, as testing of still unqualified converters disclosed few reliability problems. Nevertheless, the new system would undergo more improvements prior to the final 200-hour mean time before failure tests in July 1973.
The Ds were the first of the F-4s to go home under the United States SEA withdrawal program. F-4Ds of the 12th TFW's 389th TFS, in South Vietnam since March 1966, started leaving Phu Cat Air Base in late October 1971. However, Constant Guard III sent 4 F-4D squadrons to Takhli RTAFB, in May 1972 TAC's biggest single unit deployment ever during a crisis.
In spite of concurrent modifications, the F-4D would still lack the lower speed and higher attack angle of the slat equipped F-4E. Yet, desirable as it was, retrofit of the D appeared remote. There would be no modernization money for such a project until at least past 1974.
The USAF inventory stood at 515 F-4Ds (against total procurement of 793), 14 of which were used for testing. Altogether, 15 of 19 fully equipped F-4D squadrons were overseas. Wherever the place, the Air Force planned to retain most Ds for many years.
The Air Force used the F-4D to flight test the AGM-65A Maverick, a new tactical air to ground missile for hard targets, such as tanks and field fortifications. The first launch resulted in a direct hit on an M-41 tank.
Thirty two of the Air Force F-4Ds were sold to Iran in 1968. Deliveries, started in 1968, were completed in 1969.