should remain constant when the airplane is in level flight,  any deviation from the desired altitude signals the need for a  pitch change. If the aircraft is gaining altitude, the nose must  be lowered.  [Figures 7-7  and  7-8] The rate of movement of the altimeter needle is as important  as its direction of movement in maintaining level flight  without the use of the attitude indicator. An excessive pitch  deviation from level flight results in a relatively rapid change  of altitude; a slight pitch deviation causes a slow change.  Thus, if the altimeter needle moves rapidly clockwise, assume  a considerable nose-high deviation from level flight attitude.  Conversely, if the needle moves slowly counterclockwise to  indicate a slightly nose-low attitude, assume that the pitch  correction necessary to regain the desired altitude is small.  As the altimeter is added to the attitude indicator in a cross- check, a pilot learns to recognize the rate of movement of  the altimeter needle for a given pitch change as shown on  the attitude indicator.  To practice precision control of pitch in an airplane without  an attitude indicator, make small pitch changes by visual  reference to the natural horizon and note the rate of movement  of the altimeter. Note what amount of pitch change gives  the slowest steady rate of change on the altimeter. Then  practice small pitch corrections by accurately interpreting  and controlling the rate of needle movement.  An instructor pilot can demonstrate an excessive nose-down  deviation (indicated by rapid movement of the altimeter  needle) and then, as an example, show the result of improper  corrective technique. The normal impulse is to make a  large pitch correction in a hurry, but this inevitably leads  to overcontrolling. The needle slows down, then reverses  direction, and finally indicates an excessive nose-high  deviation. The result is tension on the controls, erratic control  response, and increasingly extreme control movements. The  correct technique, which is slower and smoother, returns the  airplane to the desired attitude more quickly, with positive  control and no confusion.  When a pitch error is detected, corrective action should be  taken promptly, but with light control pressures and two  distinct changes of attitude: (1) a change of attitude to stop  the needle movement and (2) a change of attitude to return  to the desired altitude.  When the altimeter indicates an altitude deviation, apply  just enough elevator pressure to decrease the rate of needle  movement. If it slows down abruptly, ease off some of the  pressure until the needle continues to move, but ease off  slowly. Slow needle movement means the airplane attitude  is close to level flight. Add slightly more corrective pressure  to stop the direction of needle movement. At this point, level  flight is achieved; a reversal of needle movement means  the aircraft has passed through it. Relax control pressures  carefully, continuing to cross-check since changing airspeed  causes changes in the effectiveness of a given control  pressure. Next, adjust the pitch attitude with elevator pressure  for the rate of change of altimeter needle movement that is  correlated with normal pitch corrections and return to the  desired altitude.  As a rule of thumb, for errors of less than 100 feet, use a half  bar width correction.  [Figures 7-9  and  7-10]  For errors in  excess of 100 feet, use an initial full bar width correction.  [Figures 7-11  and 7-12]  Practice predetermined altitude  changes using the altimeter alone, then in combination with  the attitude indicator.  The VSI, like the altimeter, gives an indirect indication of  pitch attitude and is both a trend and a rate instrument. As  a trend instrument, it shows immediately the initial vertical  movement of the airplane, which disregarding turbulence  can be considered a reflection of pitch change. To maintain  level flight, use the VSI in conjunction with the altimeter and  attitude indicator. Note any positive or negative trend of the  needle from zero and apply a very light corrective elevator  7-4 Vertical Speed Indicator (VSI) Figure 7-8.  Pitch correction following altitude increase—lower  nose to correct altitude error. Figure 5-8. Pitch correction following altitude increase-lower nose to correct attitude error.  Figure 7-7.  Using the altimeter for pitch interpretation, a high  altitude means a nose-high pitch attitude. Figure 5-7.  Using the altimeter for pitch interpretation, a high altitude means a nose-high pitch attitude.  30.0  29.9  29.8  30.0  29.9  29.8 