The description of human pilot dynamic characteristics in mathematical terms compatible with flight control engineering practice is an essential prerequisite to the analytical treatment of manual vehicular control systems. The enormously adaptive nature of the human pilot makes such a description exceedingly difficult to obtain, although a quasi-linear model with parameters which vary with the system task variables had been successfully applied to many flight situations. The primary purposes of the experimental series reported are the validation of the existing quasi-linear pilot model, and the extension of this model in accuracy and detail.