We introduce a modified Chalker-Coddington network model describing the interplay of backscattering and the bending action of a weak magnetic field. This results in the quantum Hall transition in a non-quantizing magnetic field, where the critical energy increases with the decrease of magnetic field. Our conclusions are in accord with conjecture proposed by Khmelnitskii in 1984 which is called the levitation of delocalized states, and was introduced to reconcile the scaling 2d theory and the necessity of a delocalized state for a quantum Hall transition.