Abstract Drilling lags behind other industries in the implementation of automation. One reason for this is the variability of drilling operations and uncertainty in knowing what is being drilled at any given time. A closed-loop system that continually monitors drilling parameters and drilling performance in real time and constantly adjusts weight on bit (WOB) and rotary speed (RPM) maximizes instantaneous rate of penetration (ROP). The system has been tested in more than 15 drilling operations around the world in both advise and control modes. Field tests show an improvement in ROP typically greater than 10% versus nonautomated operations. Maximum benefit is realized when automation is implemented by means of a closed-loop system, whereby the set points for WOB and RPM are directly fed to the controls of the drilling rig. The algorithm, the closed-loop system, and the performance improvement delivered by this system are currently subject to certain operational constraints, but these will be addressed by future enhancements.