text: (2) Power setting is the primary control 
  
  of altitude, i.e., rate of cl&b/descent. 
  
  With the exception of the transient conditions 
  of flight which occur during maneuvers and 
  acrobatics, the conditions of steady flight will 
  be applicable during such steady flight condi- 
  tions as cruise, climb, descent, takeoff, ap- 
  proach, landing, etc. A clear understanding 
  of these two principles will develop good, safe 
  techniques applicable to any sort of 
  flying 
  airplane. 
  
  The primary control of airspeed during 
  steady flight conditions is the angle of attack. 
  However, changes in airspeed will necessitate 
  changes in power setting to maintain altitude 
  because of the variation of power required with 
  The primary control of altitude 
  velocity. 
  (rate of climb/descent) is the power setting. 
  If an airplane is being flown at a particular 
  airspeed in level flight, an increase or decrease 
  in power setting will result in a rate of climb 
  or descent at this airspeed. While the angle 
  of attack must be maintained to hold airspeed 
  in steady flight, a change in power setting will 
  necessitate a change in nttitude;to.accommodate 
  the new flight path direction. These princi- 
  ples form the basis for “attitude” 
  flying tech- 
  nique, i.e., “attitude plus, power equals per- 
  formance,” and provide .a background for 
  good instrument flying technique as well as 
  good flying technique for all ordinary flying 
  conditions. 