the top of the instrument move in the same direction from  that in which the aircraft is actually banked. Some other  models move in the opposite direction from that in which  the aircraft is actually banked. This may confuse the pilot if  the indicator is used to determine the direction of bank. This  scale should be used only to control the degree of desired  bank. The relationship of the miniature aircraft to the horizon  bar should be used for an indication of the direction of bank.  The attitude indicator is reliable and the most realistic flight  instrument on the instrument panel. Its indications are very  close approximations of the actual attitude of the aircraft.  An adjustment knob is provided with which the pilot may  move the miniature aircraft up or down to align the miniature  aircraft with the horizon bar to suit the pilot’s line of vision.  Normally, the miniature aircraft is adjusted so that the wings  overlap the horizon bar when the aircraft is in straight-and­ level cruising flight.  The pitch and bank limits depend upon the make and model  of the instrument. Limits in the banking plane are usually  from 100° to 110°, and the pitch limits are usually from 60°  to 70°. If either limit is exceeded, the instrument will tumble  or spill and will give incorrect indications until realigned. A  number of modern attitude indicators do not tumble.  Every pilot should be able to interpret the banking scale  illustrated in  Figure 8-24.  Most banking scale indicators on  The heading indicator is fundamentally a mechanical  instrument designed to facilitate the use of the magnetic  compass. Errors in the magnetic compass are numerous,  Heading Indicator  Figure 8-24.  Attitude representation by the attitude indicator corresponds to the relation of the aircraft to the real horizon.  8-19  20  20  I0  I0  I0  I0  20  20  TEST STBY PWR  B a n k s c a l e Descending left bank  2 0  2 0  I 0  I 0  I 0  I 0  2 0  2 0  TEST STBY PWR  Straight descent  20  20  I0  I0  I0  I0  20  20  TEST STBY PWR  Descending right bank  2 0  2 0 $_{I}$0  I 0 $_{I}$0  I 0 2 0  2 0  TEST STBY PWR  Level left bank  2 0  2 0  I 0  I 0  I 0  I 0  2 0  2 0  TEST STBY PWR  Level right bank  2 0  2 0 $_{I}$0  $_{I}$0  $_{I}$0  I 0 2 0  2 0  TEST STBY PWR  Climbing left bank  2 0  2 0  I 0  I 0 I 0  I 0  2 0  2 0  TEST STBY PWR  Straight climb  20  20  I0  I0  I0  I0  20  20  TEST STBY PWR  Climbing right bank  2 0  2 0 $_{I}$0  I 0 $_{I}$0  I 0 2 0  2 0  TEST STBY PWR  Artificial horizon  Adjustment knob  Pointer  60° 45°  20° 10°  30°  90°