The HSI-323A is a 3ATI panel-mounted, internally lighted Horizontal Situation Indicator that provides a pictoral display of the horizontal navigation situation, plus manual controls for course and heading selection.

The Model 323A is an excellent choice for tandem training missions that are directed to prepare student pilots to step into one of thousands of current high performance aircraft. Its conventional fixed-format display elements avoid the confusion that can be created when training is conducted on menu selected, multi-function displays, which at best, merely simulate the instrumentation in the target aircraft. Sunlight readability is not an issue with the Model 323A.

The Model 323A was originally designed for the Alpha-Jet tandem trainer and features Master/Slave modes which allow the instructor to monitor the student’s course selections. However, the design features multiple embedded processors that can be combined with custom firmware to facilitate customer specified operation for a variety of input signal formats from both the analog and digital domains.


  • Servo-driven heading display card with warning flag for invalid heading data
  • Two servo-driven bearing pointers, each with a parking feature for invalid bearing data
  • Selected course pointer that supports servo-driven and manually actuated modes of operation
  • Lateral deviation bar, TO-FROM pointer and warning flag for invalid navigation data
  • Manually actuated selected heading marker
  • Digital distance display
  • Digital selected course display
  • Accepts data in ARINC 582 and ARINC 407 formats for operation in TACAN, VOR, Inertial Reference Systems and Localizer modes
  • Master/Slave Mode Selection to display student’s course selection on instructor’s HSI for tandem trainer configurations such as the Alpha-Jet and Tucano aircraft
  • Bearing pointer #1 processes and displays navigation data selected from either of two independent sensors. Selection is accomplished using an external mode-switch or hard wired where dual inputs are not required. One digital input (ARINC 582) and one analog synchro input (ARINC 407) are provided to accommodate a variety of equipment configurations
  • Bearing pointer #2 processes and displays digital navigation data conforming to ARINC 582
  • Deviation from the selected course is calculated within the HSI and displayed using data from any of the three possible bearing inputs. Selection of the data source is accomplished using an external mode-switch or hard wired where multiple inputs are not required
  • Localizer mode (ILS Energize) provides access to drive the lateral deviation bar and warning flag from the unit’s rear connector, using standard DC analog signals

Electrical Interface

  • Connectors: Electrical interface (power and signal) 37-pin circular connector, type JTP02RE-14-35P, conforming to MIL-C-38999 Series II. Mating connector (part of aircraft harness) type JT06RE-14-35S (SR)
  • Integral Lighting: Operating voltage 0 to 5 volts DC
  • Primary Power: 28 VDC bus in accordance with MIL-STD-704 Current consumption less than 0.5 amp

Environmental Conditions

  • Storage Temperature -40° C to + 85° C
  • Operating Temperature -40° C to +55° C
  • Altitude: Sea level to 55,000 feet (16,764 meters)
  • Shock: 15 g
  • Vibration:
    (a) Sine Vibration 0 to 15 Hz: 2.0 mm amplitude
    (b) Sine Vibration 15 to 2000 Hz: 2.0 g acceleration
  • Acceleration: MIL-STD-810D, method 513.3
  • Crash Safety: 30 g
  • Power Input: MIL-STD-704A
  • EMI / EMC: MIL-STD-461A
  • Magnetic Effect: DO-160D, Category A
  • Fungus: DO-160D, Category F
  • Salt Fog: MIL-STD-810D, method 509.2
  • Sand and Dust: DO-160D, Category D

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Typical Applications

  • Trainer Aircraft
  • The HSI-323A is an ideal choice for both fixed and rotary wing aircraft where a rugged, highly reliable instrument is required
  • This newly designed 3ATI HSI incorporates the latest advances in device and embedded processor technology, while retaining the advantages afforded by traditional hard-presentation display elements preferred by many pilots