Optimization of glides for constant wind fields and course headings

Theory and experiment are presented for optimal combinations of glide speeds and crab angles that minimize the glide slope at any arbitrary angle to the wind along a constant course heading. The optimization scheme is formulated for constant wind speeds, wind direction, and air mass sink rates. An analytic solution is found in the asymptotic limit of a small crosswind component. A general solution is obtained by seeded iterations with a Taylor series expansion about that limit. The solution was verified in test flights with quartering tailwinds and direct crosswinds at the 700, 500, and 300 mb levels. It was concluded that relatively small pilot-induced speed errors result in significant glide slope degradations with unnecessary and potentially dangerous altitude losses. Applications of the results are considered for wind fields that vary slowly in space, such as lee waves and Rossby