The M247 Sergeant York DIVAD (Division Air Defense) was a self-propelled anti-aircraft gun (SPAAG), developed by Ford Aerospace in the late 1970s.

The Sergeant York was intended to fight alongside the M1 Abrams and M2 Bradley in the U.S. Army, in a role similar to the Soviet ZSU-23-4 and German Flakpanzer Gepard.

Despite the use of many off the shelf technologies that were intended to allow rapid and low-cost development, a series of technical problems and massive cost overruns resulted in the cancelation of the project in 1985.

While capable for the era it was designed in, by the time it reached widespread service in the late 1950s it was clear that it was ineffective against high-speed jet-powered targets.

Mauler mounted a nine-missile magazine on top of an adapted M113 Armored Personnel Carrier chassis, along with detection and tracking radars.

Mauler featured a completely automatic fire control system, with the operators simply selecting targets and pressing "OK".

The M163 VADS combined the M61 Vulcan cannon, the M113 chassis, and an all-optical fire control system with a simple lead-computing gunsight.

Both vehicles were optionally supported by the AN/MPQ-49 Forward Area Alerting Radar (FAAR), but this system was towed by the Gama Goat and could not be used near the front lines.

At one point the Army started to become concerned about developments in sensor technologies that would allow attacks by fixed-wing aircraft at night or in bad weather.

The U.S. led the field with their TOW missile on the UH-1 Iroquois, demonstrating this powerful combination in combat in the Vietnam War's 1972 Easter Offensive.

[7] The Soviets initially lagged behind the U.S., but the introduction of the 9K114 Shturm missile on the Mil Mi-24 (called the "Hind" by NATO) in the 1970s offered the USSR a level of parity.

[12] Colonel Russell Parker testified before the Senate Armed Services Committee in March 1977 that "We expect this somewhat unorthodox approach to permit a much reduced development time, thus resulting in an earliest fielding date, albeit with higher but acceptable risks... the manufacturer will be required by the fixed price warranty provisions, to correct deficiencies.

The DIVAD's requirement demanded that the entrants be based on the M48 Patton tank chassis, provided by the Army, which were held in large quantities in surplus depots.

[13] Sperry Rand entered a system based on their older Vigilante gun, modified to fire the 35 mm round from the Oerlikon KDA series, widely used in NATO in the anti-aircraft role.

The radars were mounted on booms to give them a clear view of the sky, and both had the ability to be folded down to reduce the vehicle's height during travel.

In addition, FACC had developed a proximity-sensing round for the 40 mm, which increased probability of a kill, and the shell carried either a greater explosive charge or higher deadweight mass than the smaller anti-aircraft platforms.

After the 29-month Phase One trial, Ford's entry was selected as the winner of the DIVADs contest on 7 May 1981, and given a fixed-price $6.97 billion development and initial production contract for deliveries at various rates.

[17] The decision was controversial, as the General Dynamics entry had "outscored" the Ford design consistently in testing, nineteen "kills" to nine by most accounts.

When the guns were pointed upward to fire on high-angle targets, the barrels projected into the radar's line of sight and further confused the system.

[6][18] The RAM-D (reliability, availability, maintainability and durability) tests ran from November 1981 to February 1982, demonstrating a wide range of operation concerns.

[16] The turret proved to have too slow a traverse to track fast moving targets, and had serious problems operating in cold weather, including numerous hydraulic leaks.

When the computer was activated, it immediately started aiming the guns at the review stands, causing several minor injuries as members of the group jumped for cover.

To add to the problems, another generation of Soviet helicopter and missile designs was pushing their envelope out to 6,000 metres (6,600 yd), rendering DIVADs ineffective at long range.

[6] As Washington became increasingly fed up with the DIVAD's problems, Secretary of Defense Caspar Weinberger ordered a $54 million series of battlefield-condition tests.

Congress authorized production money to keep the program alive through a test-fix-test cycle but with a caveat; the funds would be released only if Weinberger certified that the gun "meets or exceeds the performance specifications of its contract."

[16] Initial production tests run from December 1984 to May 1985 turned up a continued variety of problems, failing 22 of 163 contract requirements, and 22 serious failures in operational readiness.

[16] Contrary to the Army's earlier reports, OT&E Director Jack Krings said the tests showed, "the SGT YORK was not operationally effective in adequately protecting friendly forces during simulated combat, even though its inherent capabilities provided improvement over the current [General Electric] Vulcan gun system.

[22] He said, "the tests demonstrated that while there are marginal improvements that can be made in the York gun, they are not worth the additional cost-so we will not invest any more funds in the system.

"[15] Noting that canceling the project did not imply a lack of need, he started the process of studying a missile-based system to fill the same niche.