Two principal issues were.investigated in this experiment: (1) to determine if the performance of an operator controlling a simulated space vehicle was affected by variable transmission delays; and (2) to determine if an approximate predictor cue enhanced the operator's ability to control the vehicle. The study employed two independent variables, delay variability and prediction. There were four levels, or ranges, of delay variability; 2.50 ± 0.00, 2.50 ± 0.25, 2.50 ± 0.50, and 2.50 ± 1.00 s, and two levels of prediction, with and without prediction. The amount of fuel used to complete the task, the time to complete the task, error score (weighted deviations from the desired flight path), and a Cooper-Harper subjective rating were the dependent measures used to gauge the performance of the operator. Each of the eight treatment combinations contained three trials for the 12 operators to perform. The results of this experiment indicate that the greater the delay variability, the greater is the amount of fuel used for each task and the greater is the perceived difficulty. Prediction did not significantly enhance the operator's ability to control the vehicle. This result is probably due to one of two reasons: (1) the task itself was too easy; thus, the predictor did not assist the operators in completing the task, or (2) since the predictor was not completely accurate, the operators may have lacked confidence in its ability to improve their performance. Consequently, this result suggests that a predictor cue may not be useful for this type of situation. Recommendations are suggested for further research efforts associated with predictors used in conjunction with variable delay conditions. / M.S.