Advanced Attack Helicopter The Advanced Attack Helicopter ( AAH ) was a United States Army program to develop an advanced ground attack helicopter beginning in 1972 . The Advanced Attack Helicopter program followed cancellation of the Lockheed AH - 56 Cheyenne . After evaluating industry proposals , the AAH competition was reduced to offerings from Bell and Hughes . Following a flight test evaluation of prototypes , Hughes ' YAH - 64 was selected in December 1976 . Background . During the mid - 1960s , the United States Army initiated the Advanced Aerial Fire Support System ( AAFSS ) program , which led to the development of the Lockheed AH - 56 Cheyenne for use in the anti - tank gunship role . The US Army pursued the AH - 1G HueyCobra as an " interim type " for the " jungle fighting " role . However , the Army ' s broader concern was the task of protecting Western Europe from the legions of Warsaw Pact armor to the east . The main scenario used by NATO throughout the Cold War was that , if the Soviet Union and Warsaw Pact forces were to conduct a massive tank offensive attack Western Europe , they would probably cross either the Fulda Gap ( capturing Frankfurt first and then aiming for the westward bend of the Rhine south of Wiesbaden : a total distance of just 85 miles ) , or cross the North German Plain ( see map ) . The Advanced Attack Helicopter was conceived from the need to defend against such an attack . In 1971 , political friction increased between the Army and the Air Force over the close air support ( CAS ) mission . The Air Force asserted that the Cheyenne would infringe on the Air Force ' s CAS mission in support of the Army , which had been mandated with the Key West Agreement of 1948 . The Department of Defense ( DOD ) conducted a study which concluded that Air Force ' s A - X program , the Navy ' s proposed Harrier , and the Cheyenne were significantly different that they did not constitute a duplication of capabilities . The Army convened a special task force under General Marks in January 1972 , to reevaluate the requirements for an attack helicopter . The task force conducted flight evaluations of the AH - 56 , along with two industry alternatives for comparison ; the Bell 309 King Cobra and Sikorsky S - 67 Blackhawk . In 1972 , the Army conducted a competitive fly - off of the helicopters from the spring 1972 until July 1972 . The Army determined the three helicopters could not fulfill its requirements . In April 1972 , the Senate published its report on CAS . The report recommended funding of the Air Force ' s A - X program , which would become the A - 10 Thunderbolt II , and limited procurement of the Harrier for the Navy . The report never referred to the Cheyenne by name and only offered a lukewarm recommendation for the Army to continue to seek to procure attack helicopters , so long as their survivability could be improved . The Cheyenne program was canceled by the Army on 9 August 1972 . The helicopter ' s large size and inadequate night / all - weather capability were reasons stated by the Army for the cancellation . History . Following the cancellation of the AH - 56 Cheyenne the US Army sought an aircraft to fill an anti - armor attack role . The Army wanted an aircraft better than the AH - 1 Cobra in firepower , performance and range . It would have the maneuverability to fly nap - of - the - earth ( NoE ) missions . On 17 August 1972 , the Army initiated the Advanced Attack Helicopter ( AAH ) program . AAH sought an attack helicopter based on combat experience in Vietnam , with a lower top speed of 145 knots ( 269 km / h ) and twin engines for improved survivability . To this end , the US Army issued a Request For Proposals ( RFP ) for an Advanced Attack Helicopter ( AAH ) in 15 November 1972 . The AAH requirements for reliability , survivability and life cycle costs were very similar to the UTTAS requirements . The Army specified that the AAH was to be powered by twin General Electric T700 turboshaft engines that produce 1 , 500 shp ( 1 , 120 kW ) each . The T700 was the same powerplant fit specified for a new Army utility helicopter competition that would be won by the UH - 60 Black Hawk . The AAH would be armed with a 30 millimeter cannon and 16 TOW anti - tank missiles . The missile armament specification was later modified to include an alternate load of 16 laser - guided AGM - 114 Hellfire anti - tank missiles . Hellfire was then in development and promised greater range and lethality than TOW . Proposals were submitted by five manufacturers : Bell , Boeing - Vertol ( teamed with Grumman ) , Hughes Aircraft , Lockheed , and Sikorsky . In June 1973 , Bell and Hughes Aircraft ' s Toolco Aircraft Division ( later Hughes Helicopters ) were selected as finalists , and were each awarded contracts for the construction of two prototype aircraft . This began the phase 1 of the competition . Each company built two prototype helicopters for a flight test program . Bell ' s Model 409 / YAH - 63A prototype featured a three - wheel landing gear in a tricycle arrangement , and placed pilot in the front of cockpit instead of the usual rear seat to help with nap of earth flying . Hughes ' Model 77 / YAH - 64A prototype featured a three - wheel landing gear with the third gear at its tail . Its cockpit placed the pilot in the rear seat . Faced with a flight deadline of the end of September , Hughes ' YAH - 64 first flew on 30 September 1975 , while Bell ' s YAH - 63 first flew on 1 October . The second YAH - 64 ' s first flight was on 22 November , and second YAH - 63 flew on 21 December 1975 . The first YAH - 63 crashed in June 1976 , but a static test prototype was brought up to flight standard and , along with the second prototype , entered the flyoff against Hughes ' YAH - 64s . The Army put all four helicopters through demanding program of flight testing during 1976 . The Army flyoff began in June of that year . A separate competition was conducted for the sensor and targeting suite for the AAH , with Martin Marietta and Northrop submitting proposals in November 1976 . During the prototype evaluation , the Army changed the AAH primary antitank weapon from the proven TOW wire - guided missile to the new Hellfire laser - guided missile , with over twice the effective range . This was risky because Hellfire had not even been flown at the time , with the initial development contract with Rockwell International signed in October 1976 . Selection and afterward . After evaluating test results , the Army selected Hughes ' YAH - 64A over Bell ' s YAH - 63A on 10 December 1976 . Both designs were regarded as good , but the Hughes design seemed to have an edge in survivability . Reasons for selecting the YAH - 64A included its more damage tolerant four - blade main rotor and reduced stability of the YAH - 63 ' s tricycle landing gear arrangement . The AH - 64A then entered phase 2 of the AAH program . This called for building three preproduction AH - 64s , and upgrading the two YAH - 64A flight prototypes and the ground test unit up to the same standard . Weapons and sensor systems were integrated and tested during this time , including the new Hellfire missile . The Phase 2 program suffered through a number of delays for various reasons and stretched out to over five years . First Phase 2 flight , of an upgraded initial prototype , was on 28 November 1977 , with first flight of a new - build preproduction prototype on 31 October 1979 . Initial Hellfire launches had already taken place by then , with first firings in April 1979 . A competitive evaluation of preproduction helicopters , one fitted with the Martin Marietta sensor / targeting suite and the other fitted with the Northrop suite , was performed , with Martin Marietta winning the competition in April 1980 . An initial production order for 11 " AH - 64A Apache " attack helicopters was issued on 26 March 1982 .