A multi-plane annular brush seal is provided. The brush seal includes a plurality of bristles attached to a front plate and a back plate. The back plate has a BP base end, a first BP inner side surface, a BP transition surface, a second BP inner side surface, and a BP tip end. The first BP inner side surface extends from the BP base end to the BP transition surface, and the second BP inner surface extends from the BP transition surface to the BP tip end. At any given circumferential position of the brush seal, the first BP inner side surface extends substantially parallel to a first plane, and the second BP inner side surface extends substantially parallel to a second plane. The first plane is skewed from the second plane by an obtuse angle.