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Instruments

Overview

Work in progress: many gauges are getting an overhaul, giving them some physicality and changing their behavior, based on reference videos, manuals, pilot feedback and filling in the gaps with educated guesses until I get better references.

Note

Some gauges have small calibration issues. Your mechanic tells you that's fine, don't worry about it.

Note

For users of the Turbine Duke sound mod: All the gyros are simulated individually, if you can't appreciate the concert they play for you during spool-up, use the Headset button. All gyros are electrical, their load is simulated. Our Twotter doesn't need or have a vacuum system.

HSI

The Horizontal Situation Indicator is based on the Bendix/King KI 525A.

  • Gyro: CPT slaved at 180°/min; FO free-DG with drift. Chaos-walk precession while spooling.

  • Course pointer: 30°/s slew. FO references the CPT value.

  • Flags: NAV if the instrument doesn't receive a signal in VLOC mode. HDG on power failure and while the gyro is spooling up.

  • AP will disconnect when the HDG flag is up.

  • KI-227 ADF cards optionally slaved to per-side gyro.

  • The Slaving Control Unit does not exist in the visual model. It is only available on the Instruments tab of the EFB app.

Altimeters

The captain's is based on an Intercontinental Dynamics Corporation Encoding Altimeter (28V), a servo-driven encoding unit, not a plain aneroid. Everything that moves on the face is driven by the motor, the needle as well as the drums. The first officer's is a plain aneroid, connected to static and needing no power at all.

The drums are geared. They sit locked on their current digit until the hundreds drum passes 920, then roll through to the next in the last eighty feet. The ten-thousands drum only moves in that same eighty-foot window before each ten thousand.

When the instrument loses power, it freezes. The Kollsman scale still turns and moves needle and drums, because that linkage is mechanical.

Note

Implementing the correct look for the behavior of the Baro knob made it necessary to calculate the altitude instead of displaying the sim's "cinematic" indicated altitude. The altitude needle moves a bit choppier, which might or might not be the correct behavior.

Whiskey Compass

The stock sim compass is pretty much perfect. All I added to it was a deflection when Windshield Heat is in use and the thermostat turns on the heating elements. The amplitude of the deflection depends on the aircraft's magnetic heading and attitude.

Reviewed 2026-09-05.