Helicopter flight controls blades collectively ("i.e.," all at the same time) and independent of their position. Therefore, if a collective input is made, all the blades change equally, and as a result, the helicopter increases or decreases its total lift derived from the rotor. In level flight this would cause a climb or descent, while with the helicopter pitched forward an increase in total lift would produce an acceleration together with a given amount of ascent. The collective pitch control in a Boeing CH-47 Chinook is called a "thrust control", but serves the same purpose, except that it controls two rotor systems, applying
1978 Iranian Chinook shootdown damaged helicopter and opened fire with GSh-23L 23-mm gun, spending a total of 72 rounds in two passes and hitting the starboard engine of the CH-47C. The Iranian pilot was lucky enough to manage a landing near the Soviet border post at Gjaurs. All four crew members survived, but were subsequently captured by Soviet border guards. The remaining two Chinooks escaped, crossing back into Iranian airspace. Despite a severe loss of life for the IIAF, the incident was played down by both sides, and the Soviets subsequently permitted the damaged Chinook to be repaired by Iranians and flown back to