Left Instrument Panel

Servopneumatic Altimeter

The servopneumatic altimeter provides altitude indication using both electrical and pressure-based systems.

Altimeter Readout

The altimeter readout (1) displays altitude using three digital drums for 10,000, 1,000, and 100 feet, and a pointer on a circular scale indicating hundreds of feet.

A pointer on the circular scale provides continuous indication in hundreds of feet.

Baroset Knob

The baroset knob (2) sets local barometric pressure in inches of mercury (in.Hg).

This setting only affects the local altimeter display. Other CADC-driven digital indicators use a fixed 29.92 in.Hg reference.

Local Barometric Pressure Window

The local barometric pressure window (3), also known as the Kollsman window, displays the selected pressure setting.

Mode Switch

The mode switch (4) selects altimeter operating mode and is spring-loaded from RESET.

• RESET - When CADC power and altitude data are available, holding RESET for approximately three seconds enables normal servoed operation.
• STBY - Selects backup pressure mode.

If CADC data or electrical power is absent for more than three seconds, the system automatically reverts to standby mode.

STBY Flag

The STBY flag is a red standby indication that appears when the altimeter is operating in backup (standby) mode (not visible in this image).

💡 At high speeds and below 10,000 feet, pressure effects can produce significant readout errors: up to 1,200 feet when transonic and up to 4,000 feet when supersonic.

Airspeed Mach Indicator

The airspeed Mach indicator displays indicated airspeed and Mach number.

Airspeed Dial

The airspeed dial (1) integrates multiple scales to display both indicated airspeed and Mach number.

Outer Airspeed Scale

The outer indicated airspeed scale (2) displays airspeed values up to 200 knots.

Inner Airspeed Scale

The inner airspeed scale (3) displays airspeed from 200 to 850 knots.

This scale remains covered by the dial until applicable.

Mach Number Scale

The Mach number scale (4) moves relative to airspeed to indicate current Mach number.

Indicated Airspeed Index Pointer

The indicated airspeed index pointer (5) can be set to mark a desired airspeed.

Mach Number Index Pointer

The Mach number index pointer (6) marks a selected Mach number.

(Not visible in the referenced image.)

Safe Mach Number Index Pointer

The safe Mach number index pointer (7) displays the maximum safe Mach number calculated by the CADC.

(Not visible in the referenced image.)

Index Selector Knob

The index knob (8) is a push-pull control.

One position adjusts the airspeed index pointer, and the other adjusts the Mach index pointer.

Standby Attitude Indicator

The standby attitude indicator provides independent attitude reference.

OFF Flag

The OFF flag (1) appears when the instrument is unpowered or caged.

Cage and Trim Knob

The cage and trim knob (2) controls indicator caging and pitch trim.

• Pulled out - Indicator is caged.
• Pushed in - Indicator is uncaged and pitch trim may be adjusted by rotating the knob.

UHF Remote Indicator

The UHF remote indicator provides a cockpit readout of ARC-159 radio tuning.

The remote display shows the selected frequency or preset channel for UHF 1.

The TEST button initiates an indicator self-test. A successful test results in a display of 888.888.

The DIM knob controls indicator display brightness.