text: One of the important factors affecting the 
  touchdown 
  
  landing roll distance is landing 
  speed. Any excess velocity at landing causes 
  a large increase in the minimum stop distance 
  and it is necessary that the pilot control the 
  landing precisely so to land at the appropriate 
  speed. When landing on the dry, hard surface 
  runway of adequate length, a tendency is to 
  take advantage of any excess runway and 
  allow the airplane to touchdown with excess 
  speed. Of course, such- errors in technique 
  cannot be tolerated and the pilot must strive 
  for precision in all 
  Immediately 
  the airp1ar.e lift may be 
  after touchdown, 
  considerable and the normal 
  force on the 
  braking surfaces quite low. Thus, if excessive 
  braking torque is applied, the wheel may lock 
  easily at high speeds and tire failure may take 
  place suddenly. 
  
  Landing on a wet or icy runway requires 
  judicious use of the brakes because of the re- 
  duction in the maximum coefficient of friction. 
  Because of reduction in the maximum attain- 
  able value of the coefficient of friction, 
  the 
  pilot must anticipate an increase in the mini- 
  mum landing distance above that applicable 
  for the dry runway conditions. When there 
  is considerable water or ice on rhe runway, an 
  increase in landing distance on the order of 40 
  to 100 percent must be expected for similar 
  conditions of gross weight, density altitude, 
  wind, etc. Unfortunately, 
  the conditions 
  to produce poor braking action also 
  likely 
  will cause high 
  idle thrust of the turbojet 
  engine and the extreme case (smooth, glazed 
  ice or heavy rain) may dictate shutting down 
  the engine to effect a reasonable stopping 
  distance. 