History
The initial service of the OV-10A Bronco in Vietnam proved successful, leading the Marine Corps to seek a relatively inexpensive night interdiction aircraft capable of disrupting North Vietnamese soldiers and supply movements under the cover of darkness. In response, North American Rockwell and LTV Electrosystems proposed converting two aircraft for this role.
Two OV-10As were modified with the addition of an M197 20 mm electrically driven gun turret mounted beneath the rear fuselage and a Forward Looking Infrared (FLIR) turret installed in the nose. The sponsons were removed to accommodate the gun turret, and the nose was lengthened by thirty inches. These two aircraft were designated YOV-10D Night Observation Gunship System (NOGS). The aircraft were delivered to China Lake, California, in 1970 for evaluation and would serve as the basis for the future OV-10D.
Testing proved successful, and the aircraft were deployed to Vietnam to assess their combat suitability. Assigned to Light Attack Squadron Four (VAL-4) “Black Ponies” at Binh Thuy, they flew more than 200 missions between June and August 1971, providing crucial close air support. Afterward, the surviving aircraft returned to the United States for further evaluation. The Marine Corps was satisfied with the converted gunships and sought additional improvements.
As a result, the aircraft received 1,040 shp Garrett T76-G-420/421 engines and an upgraded sensor suite centered around the Texas Instruments AN/AAS-37 FLIR with an integrated laser rangefinder/designator. Most of the FLIR avionics were housed in the rear cabin. Due to budget constraints, the M197 turret was removed and the original sponson armament restored, although the fuselage retained provisions for future reinstallation of the turret. The Sidewinder missile pylons were replaced with new pylons capable of carrying external fuel tanks and a wider variety of ordnance. Whether by design or oversight, the Sidewinder capability was temporarily lost because the associated wiring was not extended into the new pylons. These modifications resulted in the OV-10D (NOS).
In 1978, the Marine Corps approved a program to convert 18 OV-10As to the OV-10D (NOS) standard. Deliveries began that same year, with eight aircraft assigned to VMO-1 at MCAS New River, North Carolina, and nine assigned to VMO-2 at MCAS Camp Pendleton, California. One aircraft remained with North American Rockwell for testing of defensive countermeasure systems. These OV-10Ds were delivered with infrared-suppressive exhaust stacks and a new infrared-suppressive green camouflage scheme.
Throughout the 1980s, all OV-10A and OV-10D aircraft received various defensive upgrades, including the AN/ALE-39 chaff and flare dispensers, AN/APR-39 radar warning receiver, and AN/ALQ-144 infrared countermeasures system. In 1985, the Service Life Extension Program (SLEP) was initiated to extend the aircraft’s service life beyond the year 2000. The program called for upgrading fourteen OV-10Ds and converting twenty-three OV-10As to the OV-10D SLEP standard. These aircraft became known as the OV-10D+, with deliveries to active squadrons beginning in 1990. Reserve squadron VMO-4 also began transitioning to the OV-10D+ in early 1991.
The OV-10D+ incorporated structural reinforcements, improved engines, updated avionics, and completely new wiring that restored Sidewinder capability. The cockpit was redesigned around a Cockpit Management System, providing both crew members with integrated control and display management of navigation, IFF, countermeasures, and weapons systems. Beginning in 1990, the OV-10D+ and surviving OV-10A airframes were modified to accept the AN/AAR-47 Missile Approach Warning System (MAWS), although the system was not operationally ready until after Operation Desert Storm. All OV-10D+ aircraft received a new Air Superiority Gray camouflage scheme.
The OV-10D+ saw extensive action during Operation Desert Storm, where it repeatedly demonstrated its tactical value. The aircraft proved to be a highly effective Forward Air Controller platform, providing close air support coordination and battlefield observation for Marine forces. Following the war, economic and political factors led to another major reduction in force. As a result, the Marine Corps began the retirement of its OV-10 squadrons. VMO-2 was deactivated in May 1993, VMO-1 in July 1993, and VMO-4 in June 1994. Their missions were passed on to F/A-18D Hornets and AH-1W Super Cobras. A number of OV-10D+ airframes were transferred to the Bureau of Alcohol, Tobacco, and Firearms (BATF) for day and night surveillance missions, while most surviving aircraft were placed in storage at the AMARC facility at Davis-Monthan Air Force Base, Arizona.
