If your plane is a component, then I believe it's orientation if constant based on how the component axes were defined originally. If your plane is not entering the model with consistent orientation, that suggest your placement transformation is rotating it rather than doing a strict translation. Once you've discerned your original orientation, it should be a simple matter of adding a rotation to orient the nose to the directional tangent to the spline then having your "up" vector rotate around the tangent until its parallel to the z-axis.