As the world's needs for cleaner, carbon-free energy sources grows, it is inevitable that we look to wind power as a viable solution to humanity's demand for electricity. Implementing some of the best features developed and tested by the pioneers of high-altitude wind power research, we introduce a new concept of a tethered wind energy conversion system, called Hawkeye, that is able to harvest the extreme power of jet stream wind. Hawkeye is an aircraft that operates in a nearly static configuration during high-speed wind at high altitudes. In this paper, we analyze the motion of the Hawkeye aircraft and present an innovative, sliding mode control algorithm that enables Hawkeye to operate in an optimal way.