text: When the normal human response lag and 
  the air- 
  control system lag are coupled with 
  plane motion, 
  reactions 
  by the pilot may furnish a negative damping 
  to the oscillatory motion and dynamic in- 
  stability exists. Since the short period motion 
  is of relatively high frequency, the amplitude 
  of the pitching oscillation can reach dangerous 
  in an unbelievably short time. 
  proportions 
  When the pilot 
  is en- 
  countered, the most effective solution is an 
  immediate release of the controls. Any at- 
  tempt to forcibly damp the oscillation simply 
  continues the excitation and amplifies the 
  oscillation. 
  removes 
  the unstable (but inadvertent) excitation and 
  allows the airplane to recover by virtue of 
  its inherent dynamic stability. 
  
  Generally, flight at high Mach number will 
  cake place at high altitude hence the effect of 
  high altitude must be separated for study. 
  All of the basic aerodynamic damping is due 
  to moments created by pitching, 
  rolling, or 
  yawing motion of the aircraft. These moments 
  the changes in angles of 
  are derived from 
  attack on 
  angular 
  rotation (see fig. 4.15). The very high true 
  flight 
  airspeeds common to high altitude 
  reduce the angle of attack changes and reduce 
  the aerodynamic damping. 
  In fact, the aero- 
  dynamic damping 
  similar to the proportion of true airspeed to 
  equivalent airspeed. Thus, at the altitude of 
  4O,C00 ft., 
  the aerodynamic damping would 
  be reduced to one-half the sea level value and 
  at the altitude of 100,000 ft. the aerodynamic 
  damping would be reduced to one-tenth the 
  sea level value. 
  
  inadvertent control 