text: Since the airplane lands at altitude with 
  the 
  same weight and dynamic pressure, the drag 
  the landing 
  and braking friction 
  toll have the same values as at sea level. As 
  long as the condition is within 
  the capability 
  of the brakes, the net retarding force is un- 
  changed and the acceleration is the same as 
  with the landing at sea level. 
  
  throughout 
  
  As a result of this relationship, a headwind 
  which is 10 percent of the landing airspeed will 
  reduce the landing distance 19 percent but a 
  tailwind (or ‘negative headwind) which is 10 
  percent of the landing speed will 
  increase the 
  landing distance 21 percent. Figure 2.33 illus- 
  trates this general effect. 
  
  To evaluate the effect of density altitude on 
  relationships 
  
  landing distance, the following 
  are used : 
  
  since an increase in altitude does not alter 
  acceleration, the effect would be due to 
  the greater TAS 
  
  The effect of ranway slope on landing distance 
  is due to the component of weight along the 
  inclined path of the airplane. The relation- 
  ship is identical to the case of takeoff per- 
  formance but the magnitude of the effect is 
  not as great. While account must be made 
  for the effect, the ordinary values of runway 
  slope do not contribute a large effect on landing 
  distance. For this reason, the selection of the 
  landing runway will ordinarily favor the direc- 
  tion with a downslope and’headwind rather 
  than an upslope and tailwind. 