HSI (KI 525A style)
A mechanical HSI with a slaved compass card, heading bug, yellow course arrow with deviation bar, glideslope pointers and red NAV, HDG and GS flags. It can show NAV 1, NAV 2, the GPS with its ENR/TERM/APR scale, or NAV 1 with an ADF needle; CRS and HDG knobs drive the simulator.
- Modeled on
- Bendix/King KI 525A-style mechanical HSI
- Category
- Flight instruments
- Size
- 1 cell
- Version
- 1.0 · 2026-10-19
- Plan
- Pro
- Simulators
- MSFS 2020 · MSFS 2024 · X-Plane 11 · X-Plane 12
Variants
NAV 1v1.0
NAV 1 (or the GPS when it drives the CDI).
Instrument picker > RECEIVER > NAV 1
NAV 2v1.0
NAV 2 course and deviation, labeled NAV2.
RECEIVER > NAV 2
GPSv1.0
GPS desired track and deviation, labeled GPS ENR / TERM / APR; CRS knob inactive.
RECEIVER > GPS
NAV 1 + ADFv1.0
NAV 1 plus a thin green ADF bearing pointer over the card.
RECEIVER > NAV 1 + ADF
Features
- Compass card slaved to the simulator's heading; stops without battery power and the HDG flag drops
- FREE mode: the card as a free gyro that slowly precesses; can be set to the magnetic compass
- Orange heading bug, yellow course arrow with deviation bar (two dots each side) and TO/FROM triangle
- Glideslope pointers on both sides (stowed without a localizer); GS flag on a localizer without glideslope
- LOC label on a localizer; BC and reversed needle when flying a localizer backwards
- GPS scale ENR / TERM (within 30 nm of the flight plan's destination) / APR (on a glidepath)
- Red NAV flag without a valid signal
- Night lighting: the face takes the panel's red flood light, the glareshield's warm light from above (stronger for instruments higher on the page) and its own light, a lamp hidden at the top of the case lighting the dial downward (Settings > Dimmers: Red flood light, Glareshield, Instruments (analog))
On the iPad
- Drag the CRS knob (lower left) to set the course; double tap it to center the needle on the station
- Drag the HDG knob (lower right) to move the heading bug; double tap it to sync the bug to the heading
- Hold the HDG knob to switch the card between slaved and FREE; in FREE, double tap HDG sets the card to the magnetic compass
- Tap elsewhere on the face to change the instrument
Settings
- Receiver: NAV 1 / NAV 2 / GPS / NAV 1 + ADF (instrument picker)
Keys and controllers
Map any of these to a key, a game controller's button or axis, or a MIDI knob (how):
- Heading bug +
- Heading bug -
- Heading bug sync
- Course +
- Course -
- Course sync
Simulator data
What the Hub reads from the simulator for this instrument, and what the instrument sends back. Names are the simulators' own: MSFS SimVars and events, X-Plane datarefs and commands.
Reads
| Value | MSFS | X-Plane |
|---|---|---|
| Heading (glass AHRS heading, else magnetic heading) (deg magnetic) | HEADING INDICATOR (degrees) | sim/cockpit2/gauges/indicators/heading_AHARS_deg_mag_pilotsim/flightmodel/position/mag_psi |
| Heading bug (deg) | AUTOPILOT HEADING LOCK DIR (degrees) | sim/cockpit2/autopilot/heading_dial_deg_mag_pilot |
| Magnetic (whiskey) compass, with its errors (deg) | WISKEY COMPASS INDICATION DEGREES (degrees) | sim/cockpit2/gauges/indicators/compass_heading_deg_mag |
| Battery master (1/0) (bool) | ELECTRICAL MASTER BATTERY (bool) | sim/cockpit2/electrical/battery_on[0] |
| Course shown on the HSI (deg) | GPS WP DESIRED TRACK (degrees)NAV OBS:1 (degrees)GPS DRIVES NAV1 (bool) | sim/cockpit2/radios/actuators/hsi_obs_deg_mag_pilot |
| Course deviation, + = course to the right (dots (-2.5..2.5)) | HSI CDI NEEDLE (number) | sim/cockpit2/radios/indicators/hsi_hdef_dots_pilot |
| TO/FROM flag: 0 off, 1 TO, 2 FROM (enum) | HSI TF FLAGS (enum) | sim/cockpit2/radios/indicators/hsi_flag_from_to_pilot |
| CDI needle valid (1/0) (bool) | HSI CDI NEEDLE VALID (bool) | sim/cockpit2/radios/indicators/hsi_flag_from_to_pilot |
| CDI/HSI navigation source: 0 GPS, 1 NAV (enum) | GPS DRIVES NAV1 (bool) | sim/cockpit2/radios/actuators/HSI_source_select_pilot |
| The NAV source is a localizer (1/0) (bool) | NAV HAS LOCALIZER:1 (bool)GPS DRIVES NAV1 (bool) | sim/cockpit2/radios/actuators/nav1_frequency_hzsim/cockpit2/radios/actuators/HSI_source_select_pilot |
| Glideslope valid (1/0) (bool) | HSI GSI NEEDLE VALID (bool) | sim/cockpit2/radios/indicators/hsi_flag_glideslope_pilot |
| Glideslope deviation (dots) | HSI GSI NEEDLE (number) | sim/cockpit2/radios/indicators/hsi_vdef_dots_pilot |
| Distance to the station / waypoint (HSI) (nm) | HSI DISTANCE (nautical miles) | sim/cockpit2/radios/indicators/hsi_dme_distance_nm_pilot |
| NAV2 OBS course (deg) | NAV OBS:2 (degrees) | sim/cockpit2/radios/actuators/nav2_obs_deg_mag_pilot |
| NAV2 receiver course deviation, + = course right (dots (-2.5..2.5)) | NAV CDI:2 (number) | sim/cockpit2/radios/indicators/nav2_hdef_dots_pilot |
| NAV2 TO/FROM: 0 off, 1 TO, 2 FROM (enum) | NAV TOFROM:2 (enum) | sim/cockpit2/radios/indicators/nav2_flag_from_to_pilot |
| NAV2 receiving a station (1/0) (bool) | NAV HAS NAV:2 (bool) | sim/cockpit2/radios/indicators/nav2_flag_from_to_pilot |
| NAV2 station has DME (1/0) (bool) | NAV HAS DME:2 (bool) | sim/cockpit2/radios/indicators/nav2_has_dme |
| NAV2 DME distance (nm) | NAV DME:2 (nautical miles)NAV HAS DME:2 (bool) | sim/cockpit2/radios/indicators/nav2_dme_distance_nmsim/cockpit2/radios/indicators/nav2_has_dme |
| GPS desired track (deg) | GPS WP DESIRED TRACK (degrees)GPS IS ACTIVE FLIGHT PLAN (bool) | Not available |
| GPS's own course deviation (dots) | GPS CDI NEEDLE (number) | sim/cockpit2/radios/indicators/gps_hdef_dots_pilot |
| GPS flight plan active (1/0) (bool) | GPS IS ACTIVE FLIGHT PLAN (bool) | Not available |
| Distance to the active waypoint (nm) | GPS WP DISTANCE (nautical miles)GPS IS ACTIVE FLIGHT PLAN (bool) | Not available |
| Aircraft latitude (deg) | PLANE LATITUDE (degrees) | sim/flightmodel/position/latitude |
| Aircraft longitude (deg) | PLANE LONGITUDE (degrees) | sim/flightmodel/position/longitude |
| ADF needle, relative bearing to the station (deg) | ADF RADIAL:1 (degrees) | sim/cockpit2/radios/indicators/adf1_relative_bearing_deg |
| ADF receiving a station (1/0) (bool) | ADF SIGNAL:1 (number) | sim/cockpit2/radios/actuators/adf1_frequency_hz |
Sends
| When you… | MSFS | X-Plane |
|---|---|---|
| Dragging the CRS knob on NAV 1 or NAV 1 + ADF, or mapped 'Course +' / '-' | VOR1_SET | sim/cockpit2/radios/actuators/nav1_obs_deg_mag_pilotsim/cockpit2/radios/actuators/hsi_obs_deg_mag_pilot (also, when HSI_source_select_pilot == 0) |
| Double tap on the CRS knob on NAV 1 / NAV 1 + ADF, or mapped 'Course sync' | VOR1_SET | sim/cockpit2/radios/actuators/nav1_obs_deg_mag_pilotsim/cockpit2/radios/actuators/hsi_obs_deg_mag_pilot (when HSI shows NAV1) |
| Dragging the CRS knob on NAV 2 | VOR2_SET | sim/cockpit2/radios/actuators/nav2_obs_deg_mag_pilotsim/cockpit2/radios/actuators/hsi_obs_deg_mag_pilot (also, when HSI_source_select_pilot == 1) |
| Double tap on the CRS knob on NAV 2 | VOR2_SET | sim/cockpit2/radios/actuators/nav2_obs_deg_mag_pilotsim/cockpit2/radios/actuators/hsi_obs_deg_mag_pilot (when HSI shows NAV2) |
| Dragging the HDG knob, or mapped 'Heading bug +' / '-' | HEADING_BUG_SET | sim/cockpit2/autopilot/heading_dial_deg_mag_pilot |
| Double tap on the HDG knob (slaved mode), or mapped 'Heading bug sync'; the Hub also sets the simulator's own directional gyro to the compass first (X-Plane DG_sync_mag, MSFS HEADING_GYRO_SET) | HEADING_GYRO_SETHEADING_BUG_SET | sim/instruments/DG_sync_magsim/cockpit2/autopilot/heading_dial_deg_mag_pilot |
Add-on aircraft with their own systems may use other variables; the Hub reads the standard ones.
Changes
The instrument's version counts what its faces share (the case, the mechanism, the data, the sounds); a face's own version counts that face alone.
- 1.0 2026-10-19
- First numbered version.
