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
Chinook wind family-relations story, and family/tribal history as well, it also seems to be a parable of a typical weather pattern of a southwesterly wind at first bringing snow, then rain, and also of the melting of a glacier, namely the Place Glacier near Gates Lake at Birken. Thus, it also tells of a migration of people to the area – or a war, depending on how the details of the legend might be read, with Chinook-Wind taking the part of Helen in a First Nations parallel to the Trojan War. The frequent midwinter thaws in Great Plains Chinook country are more