The AH-64 was developed to meet the demand for an advanced all-weather anti-tank and ground support combat helicopter with high survivability. The prototypes flew in 1975. The first production models took to the air in 1984. The AH-64 had received the nickname "Apache" 3 years earlier. The Apache has four-bladed main and tail rotors. The two pilots sit one behind the other in the cockpit with the co-pilot and therefore the gunner at the front. The armament includes nose cannon, unguided rockets and laser-guided anti-tank projectiles. In addition, an extensive range of sensitive sensors in the nose enables targets to be acquired and hit under the worst visibility conditions. Deliveries of the AH-64 began in 1985. The next step for the Apache equipment programme is found in the AH-64D Longbow which also has a mast-mounted sight (Longbow millimetre wave = Millimeter wave radar), improved armament, more powerful engines and new avionics. Since 1997 over 200 examples of the AH-64A have been converted to the Longbow variant.