Methods and systems for in-service inspection of freight car axles are provided. A camber angle of a wheel attached to a target axle is measured at one or more points in a revolution of the wheel. A determination of whether a defect is present in the target axle is made based on the measured camber angle at the one or more points in the revolution of the wheel. A determination that a defect is present in the target axle is made when a camber angle of the wheel at one or more points in the revolution of the wheel exceeds a threshold, and/or a determination that a defect is not present is made when no camber angle of the wheel at any point in the revolution of the wheel exceeds the predetermined threshold. An alert is generated in response to determining that a defect is present.