illuminate if aircraft departs more than 250 feet from the
Altitude scale. Used in conjunction with
altitude indicator needle to indicate aircraft altitude in
hundreds of feet. Subdivided into 20 foot increments.
Barometric pressure counter-drum indicator
(inches of mercury). Indicates barometric pressure in
inches of mercury that has been set by the barometric
pressure setting knob.
(5)Barometric pressure counter-drum indicator (millibars).
Indicates barometric pressure in millibars that has been
set by the barometric pressure setting knob.
Barometric pressure setting knob. Used to
manually set barometric pressure displayed in the MB
pressure displayed in the IN HG and MB windows.
conjunction with altitude scale to display aircraft altitude in
hundreds of feet.
Counter-drum altitude display. Indicates
aircraft altitude in tens of thousands, thousands, and
hundreds of feet above sea level.
Altimeter Operating Procedure.
desired altimeter setting.
Failure warning flag Check not visible.
Altitude indicator needle Check operation.
If the altimeter does not read within
70 feet of field elevation, when the
correct local barometric setting is
used, the altimeter needs calibration
or internal failure has occurred. An
error of greater than 70 feet also
nullifies use of the altimeter for IFR
1. Failure Warning Flag
2. Altitude Alert Annunciator
3. Altitude Scale
4. Barometric Pressure Counter-Drum Indicator Window
(Inches of Mercury)
5. Barometric Pressure Counter-Drum Indicator Window
6. Barometric Pressure Setting Knob
7. Altitude Indicator Needle
8. Counter-Drum Altitude Display
Figure 3-35. Pilot's Barometric Altimeter Indicator
3-91 1(3-92 blank)