text: The eficct aj wind on gliding performance is 
  similar to the effect of wind on cruising range. 
  That is, a headwind will always reduce the 
  glide range and a tailwind will always increase 
  the glide range. The maximum glide range 
  of the airplane in still air will be obtained by 
  flight at (L/D),,,,. However, when a wind is 
  present, the optimum gliding conditions may 
  not be accomplished by operation at (L/D)ma. 
  is present, 
  For example, when a headwind 
  the optimum glide speed will be increased to 
  obtain a maximum proportion of ground dis- 
  tance to altitude. 
  In this sense, the increased 
  glide speed helps to minimize the detrimental 
  effect of the headwind. 
  In the case of a tail- 
  wind, the optimum glide speed will be reduced 
  For 
  to maximize the benefit of the tailwind. 
  ordinary wind conditions, maintaining 
  the 
  glide speed best for zero wind conditions will 
  suffice and the loss or gain in glide distance 
  must be accepted. However, when the wind 
  conditions are extreme and the wind velocity 
  is large in comparison with 
  the glide speed, 
  e.g., wind velocity greater than 25 percent of 
  the glide speed, changes in the glide speed must 
  be made to obtain maximum possible ground 
  distance. 