A drive mechanism for positioning a moveable indicator in rotation about, and/or radial displacement with respect to, a fixed reference index. Dual dial cord drives are employed which are driven from respective inputs definitive of the rotation and radial displacement to be individually or compositely imparted to the moveable indicator. The pair of dial cords are attached circumferentially to diametrically opposed portions of a cylinder with the moveable indicator extending on a diameter common to those portions. The cylinder portions are confined between, and maintained in sliding tangential engagement with, respective ones of a pair of space-separated, fixed-mounted channel guides. Implementations of the cylinder portions are exampled as diametrically opposed segments of a cylinder, diametrically opposed points on a ring, and diametrically opposed circumferential extremes of a cylindrical plate.
Flight plan information is provided in the form of a series of waypoints having attributes which preferably include, among others, latitude, longitude, altitude constraint, and waypoint identifier. A flight path, defined by this information is modeled, and the flight plan model is checked against terrain information to locate any instances in which a potentially unsafe flight altitude exists. In flight, the flight path model is updated using aircraft position so that the path from the aircraft position to the next waypoint is reflected in the model. In the event that a potentially unsafe flight altitude is detected, an alert may be issued to the flight crew. The crew may then amend the flight plan or take other appropriate action.
