Altitude excursions particular to high speed aircraft are investigated in this thesis. An aerodynamic database of the XB-70 is created and a longitudinal linear model is constructed for a high speed cruise flight condition. An examination of the unpiloted aircraft dynamics revealed that the excursions were not due to a poorly handling aircraft. Thus, it is theorized that the excursions are due to pilot vehicle interactions. A classical control method developed a loop closure scheme suitable for acceptable control of the aircraft. The results showed that a pilot should close an inner loop with negative attitude feedback and an outer loop with positive flight path feedback. A modern control method analysis using an optimal control pilot model confirmed the preceding conclusions. Based on these results, the cockpit pitch attitude display resolution should be less than 1° so that the pilot will be able to perform the loop closures necessary for constant altitude flight. / Master of Science