XPDR 5537 IDNT LCL23:00:34 VOR 1 270 ° 2 1 1 2 4300 4200 4100 3900 3900 3800 4300 3600 3500 3400 3300 3200 3100 20 80 4000 4000 130 120 110 90 80 70 1 100 9 TAS 100KT OAT 7°C ALERTS NAV1 117.60 117.90 NAV2 117.90 117.60 132.675 120.000 COM1 118.525 132.900 COM2 $_{WPT }$_ _ _ _ _ _$_{ DIS }$_ _ ._ $_{NM}$ $_{DTK }$_ _ _$_{°}$ TRK 360° VOLTS 27.3 2090 NAV1 117.60 117.90 NAV2 117.90 117.60 132.675 120.000 COM1 118.525 132.900 COM2 $_{WPT }$_ _ _ _ _ _$_{ DIS }$_ _ ._ $_{NM}$ $_{DTK }$_ _ _$_{°}$ TRK 360° MAP - NAVIGATION MAP 20 20 I0 I0 2 0 I 0 2 0 2 0 I 0 I 0 2 0 I 10-57 Figure 10-100.  A typical vacuum-driven attitude indicator shown with the aircraft in level flight (left) and in a climbing right turn (right).  Figure 10-99.  Instrumentation displayed within a glass cockpit using an attitude heading and reference system (AHRS) computer.  exhaust the same amount of air when the gyro is rotating in  plane. When the gyro rotates out of plane, air tends to port  out of one side more than another. Vanes close to prevent  this, causing more air to flow out of the opposite side. The  force from this unequal venting of the air re-erects the gyro  rotor.  [Figure 10-101] In a typical vacuum-driven attitude gyro system, air is  sucked through a filter and then through the attitude indicator  in a manner that spins the gyro rotor inside. An erecting  mechanism is built into the instrument to assist in keeping the  gyro rotor rotating in the intended plane. Precession caused  by bearing friction makes this necessary. After air engages  the scalloped drive on the rotor, it flows from the instrument  to the vacuum pump through four ports. These ports all 