text: The effect of ice or frost on takeoff and land- 
  ing performance is of great importance. The 
  effects are so detrimental to the landing and 
  takeoff that no effort should be spared to keep 
  the airplane as free as possible from any ac- 
  If any ice remains 
  cumulation of ice or frost. 
  on the airplane as the landing phase approaches 
  it must be appreciated that the ice formation 
  will have reduced CL,., and incurred an increase 
  in stall speed. Thus, the landing speed will be 
  greater. When this effect is coupled with the 
  possibility of poor braking action during the 
  It is 
  landing roll, a critical situation can exist. 
  obvious that .great effort must be made to 
  prevent the accumulation of ice during flight. 
  In no circumstances should a formation of ice 
  or frost be allowed to remain on the airplane 
  wing surfaces prior to takeoff. The undesir- 
  able effects of ice are obvious but, as previously 
  mentioned, the effects of frost are more subtle. 
  If a heavy coat of hard frost exists on the wing 
  upper surface, a typical 
  in CL,.. 
  would cause a 5 to 10 percent increase in the 
  airplane stall speed. Because of this magnitude 
  of effect, the effect of frost on takeoff per- 
  formance may not be realized until 
  too late. 
  The takeoff speed of an airplane is generally 
  some speed 5 to 25 percent greater than the 
  stall speed, hence the takeoff lift coefficient 
  will be value from 90 to 65 percent of C1,,.., 
  Thus, it is possible that the airplane with frost 
  cannot become airborne at the specified take- 
  off speed because of premature stalling. Even 
  if the airplane with 
  frost were to become air- 
  borne at the specified takeoff speed, the air- 
  plane could have insufficient margin of air- 
  speed above stall and turbulence, gusts, turning 
  flight could produce incipient or con plete 
  stalling of the airplane. 