VOR 1 270 °  2  1  1  2  - 5 00  4 200  4 100  4 000  3 900  3 800  3 700  3700  3600  3500  3400  3300  3200  40 80 900 000  130  120 110 90 80 70  1 100 9 TAS 100KT 270 °  4 100  3 000  3 900  20 80 4 000 31 0 0  40 0 0  3 9 0 0  80 70 9 75 -125  3 100  4 000  3 900  70 30 950 -250  40 0 0  30 0 0  3 8 0 0  45 05 3 9 25 -375  Altitude trend vector Turn rate trend vector Airspeed trend (increasing) Figure 6-31.  Supporting instruments. Figure 4-27. pilot is made aware that the pitch attitude of the aircraft has  changed and may need adjustment. Notice in  Figure 6-31 that the aircraft is descending at a rate of 500 fpm.  The instrument cross-check necessitates utilizing these  supporting instruments to better manage altitude control.  The VSI and trend tape provide the pilot with information  The slip/skid indicator is the primary instrument for yaw.  It is the only instrument that can indicate if the aircraft is  regarding the direction and rate of altitude deviations. The  pilot is thus able to make corrections to the pitch attitude  before a large deviation in altitude occurs. The airspeed  indicator depicts an increase if the pitch attitude is lowered.  Conversely, when the pitch attitude increases, the pilot should  note a decrease in the airspeed. When flying in IMC, pilots maintain preplanned or assigned  headings. With this in mind, the primary instrument for bank  angle is the heading indicator. Heading changes are displayed  instantaneously. The heading indicator is the only instrument  that displays the current magnetic heading, provided that  it is matched to the magnetic compass with all deviation  adjustments accounted for.  [Figure 6-32] There are supporting instruments associated with bank as  well. The turn rate trend indicator shows the pilot when the  aircraft is changing heading. The magnetic compass is also  useful for maintaining a heading; however, it is influenced  by several errors in various phases of flight. Primary Bank Primary Yaw XPDR 5537 IDNT LCL23:00:34  5 338  $_{1}$1652  200  46  13.7  2300  23.0  VOR 1 270 °  2  1  1  2  4 300  4 200  4 100  4 000  3 900  3 800  4300  3600  3500  3400  3300  3200  3100  60 20 000 000  130  120 110 90 80 70  1 100 9 TAS 100KT  ALERTS  NAV1 108.00 113.00 NAV2 108.00 110.60 134.000 118.000 COM1 123.800 118.000 COM2 $_{WPT }$_ _ _ _ _ _$_{ DIS }$_ _ ._ $_{NM}$ $_{DTK }$_ _ _$_{°}$ TRK 360° Roll scale zero Slip/skid indicator Skidding turn  270 °  Roll pointer Standard rate Heading 1/2 standard rate Turn rate trend vector Figure 6-32.  Primary bank. 6-23