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
Boeing Chinook (UK variants) Operation Granby in the 1991 Gulf War, attached to large peace-keeping commitments in the Balkans, the continued British presence in Afghanistan, and in Operation Telic in the 2003 Iraq War. They provide routine supply and support missions to the British military, notably in Operation Banner in Northern Ireland. The helicopter has also been of use in military humanitarian missions and the extraction of civilians from warzones, such as the evacuation of Sierra Leone in 2000, and the evacuation from Lebanon in 2006. One Chinook in particular, known by its original squadron code "Bravo November", has come to widespread public recognition