A method for controlling a pump-down operation in a wellbore includes selecting a target value for downhole tension of a support cable and a recommended job speed to convey a wireline tool string down a section of the wellbore, generating a line speed signal for controlling a line speed of the support cable and a pumprate signal to control a pumprate of a hydraulic fluid in the wellbore, determining a first error between the target value for downhole tension and a measured value of the downhole tension, determining a second error between the recommended job speed and an actual line speed, and maintaining the target value for the downhole tension by simultaneously controlling the line speed and the pumprate using a value for the line speed signal and a value for the pumprate signal generated based on the first and second errors.