text: Area B on the “dead man’s curve” of figure 
  6.18 is critical because of ground contact flight 
  speed or rate of descent, which is based on the 
  strength of 
  the landing gear. The average 
  pilot may have difhculty in successfully flaring 
  the helicopter from a high speed flight con- 
  dition without allowing the tail rotor to strike 
  the ground or contacting the ground at an ex- 
  cessive airspeed. A less critical zone is some- 
  times shown on this curve to indicate that 
  higher ground contact speeds can be permitted 