Abstract: For precision grading of terrain by a dozer, the dozer blade can be automatically controlled based on measurements from a combination of a global navigation satellite system real-time kinematic mode (GNSS RTK) system and inertial sensors. At least one GNSS sensor and at least one inertial sensor are mounted on the dozer. Control algorithms are based on blade elevation and blade slope angle. During a period of GNSS RTK system outage, control of blade elevation is not available. Blade control is maintained by switching to control algorithms based on blade slope angle and blade pitch angle. Blade slope angle and blade pitch angle are controlled based on extrapolated target values of blade slope angle and blade pitch angle. The extrapolated target values of the angles are extrapolated from target values of the angles prior to the GNSS RTK system outage with the use of a distance travelled by the dozer.