Systems and methods are provided for installing ribs and/or spars to a wing panel while a contour is enforced. Methods include suspending a wing panel beneath a shuttle that enforces the contour, advancing the wing panel through work stations via the shuttle, and installing a rib or a spar (or another wing panel) at a work station, while the contour is enforced. Other methods include locating a wing panel beneath a shuttle, coupling adjustable-length pogos to the wing panel at locations distinct from those corresponding with an installation location, e.g. for a rib or a spar, and controlling the length of the pogos to enforce a contour to the wing panel. Some systems include a track, work stations disposed along the track, and a shuttle to advance along the track and convey a wing panel to each of the work stations while enforcing a contour onto the wing panel.