text: immediately past the incipient 
  skidding condition the coefficient of friction 
  decreases with 
  increased slip speed, especially 
  for the wet or icy runway conditions. Thus, 
  once skid begins, a reduction in friction force 
  torque must be met with a reduc- 
  and rolling 
  tion in braking torque, otherwise the wheel 
  will decelerate and lock. This is an important 
  factor to consider in braking technique because 
  the skidding tire surface on the locked wheel 
  produces considerably less retarding force than 
  when at the incipient skid condition which 
  If the 
  causes the peak coeflicient of friction. 
  wheel locks from excessive braking, the sliding 
  tire surface produces less than the maximum 
  retarding force and the tires become relatively 
  incapable of developing any significant side 
  force. Stop distance will 
  increase and it may 
  be difficult-if 
  not impossible-to control the 
  airplane when full slip is developed. In addi- 
  tion, at high rolling vel,ocities on the dry sur- 
  face runway, the immediate problem of a skid- 
  ding tire is not necessarily the loss of retard- 
  ing force but the imminence of tire failure. The 
  pilot must insure that the application of brakes 
  does not produce some excessive braking torque 
  is greater than the maximum rolling 
  which 
  torque and particular care must be taken when 
  the runway conditions produce low values of 
  friction coefficient and when the normal force 
  on the braking surfaces is small. When it is 
  difficult to perceive or distinguish a skidding 
  condition, 
  the value of an antiskid or auto- 
  matic braking system will be appreciated. 