 The Cobra family developments after the AH-1G and AH-1J variants were connected to the Bell 309.Based on the Model 309 and AH-1 Cobra, Bell derived a new prototype attack helicopter, the Model 409/YAH-63, for the Army's Advanced Attack Helicopter (AAH) competition beginning in 1972.Hughes' Model 77/YAH-64 was selected over Bell's Model 409/YAH-63 in 1976.