Airworthy AHRS system for Airborne Applications


Octantis 2 Attitude and Heading Reference System (AHRS)

MEMS-based AHRS for Airborne Application

Aeron’s Octantis 2 AHRS is a tactical class Attitude and Heading Reference System for airborne applications. The model OCT2 AN5300S AHRS has been designed as per the DO-254 standards and qualified as per MIL-STD-461E and MIL-STD-810G standards. The AHRS software has been tested through a rigorous IV&V process and certified as per DO-178B level B standards. The AHRS system has been accorded the CEMILAC (Indian Airworthiness) certification. The unit meets the performance requirements as per the RTCA-DO-334 standard.

The AHRS is an airborne qualified system and can be used as a primary or standby instrument in electronic flight instrumentation systems, cockpit displays in a wide range of fighter, transport and passenger aircrafts.

Key Features

High Reliability System

Airworthiness Certified with Redundant Sensor Configuration

Device Diagnostics

Complete Continuous Built in Test

Power Consumption

Low Power <2.5 W

External Magnetometer Interface

To facilitate the user to choose the external magnetometer data to avoid degradation caused by nearby systems

TSO Compliant Performance

Suitable for flight instrumentation, attitude indication


Low Noise Sensors

To give highly accurate attitude and heading data

Software Certification

DO178B Level B compliant software

External True Air Speed (TAS) aiding

Accepts external TAS data for velocity aiding

Isolated Interfaces and power supply

Making it resistant to electromagnetic interference on data and power lines


Comes with standard Serial RS422, RS232 interfaces

Technical Specifications



±12 g


1 mg



±450 °/s


0.1 °/s



±4 gauss


0.25 mgauss


Roll Range


Pitch Range


Roll, Pitch Static Accuracy

Less than ±1.0°

Roll, Pitch Dynamic Accuracy

Less than ±2.5°

Attitude Resolution






Less than ±2.5°




Input Voltage (isolated)

9 V to 32 V DC

Power Consumption

< 2.5 Watt


Input / Output Ports

RS232, RS422


D-Sub 15 (M24308/3-2F)

Update rate

50 Hz

Baud Rate (RS422)

Configurable, 38400 (Default)

Baud Rate (RS232)

Configurable, 9600 (Default)

Data Format


External I/Ps

True Airspeed, Magnetic Field, Pressure Altitude

Output Parameters

Euler angles, Body Accelerations, Euler Rates, BIT (Built-In-Tests)






148 (L) x 115 (W) x 63 (H)





± 50


Operating temperature

-40 to +71


Storage temperature

-55 to +90



10 to 95 (non – condensing)

% RH

MTBF (Mean Time Between Failure)

> 14000 hours (as per MIL-HDBK-217F)


Conducted Emissions, Power Leads

As per test CE102 of MIL-STD-461E (Basic Curve)

Radiated Emissions, Electric Field

As per test RE102 of MIL-STD-461E

Radiated Susceptibility, Electric Field

As per RS103, 60 V/m level of MIL-STD-461E

Conducted Susceptibility, Power lead

As per CS101 of MIL-STD-461E (Curve #2)

Conducted Susceptibility, Bulk Cable Injection

As per CS114 of MIL-STD-461E (Limit Curve #3)

Conducted Susceptibility, Bulk Cable Injection, Impulse Excitation

As per CS115 of MIL-STD-461E

Conducted Susceptibility, Damped Sinusoidal Transient, Cable and Power Leads

As per CS116 of MIL-STD-461E (IMax = 5 A)


Random Vibration Test

As per MIL-STD-810F, method 514.5C-17, Procedure I, Category 12

High Temperature Ground Survival Test

As per MIL-STD-810G, Method 501.5, Procedure I

Ground Operation Short Term Test

As per MIL-STD-810G, Method 501.5, Procedure II

Ground Operation Long Term Test

As per MIL-STD-810G, Method 501.5, Procedure II

Low Temperature Test

As per MIL-STD-810G, Method 502.5, Procedure I

Low Pressure (Altitude) Test

As per Clause, JSS55555: 2000, Revision No. 2

Humidity Test

As per MIL STD 810F, Method 507.4

Acceleration Test

Structural, MIL-STD-810G, Method 513.5, Procedure I
Operational,  MIL-STD-810G, Method 513.5, Procedure II 

Shock Survival Test

As per MIL-STD-810E, Method 516.4 Procedure I

Transit Drop Test

As per MIL-STD-810F, Method 516.5, Procedure IV

Thermal Shock Test

As per MIL-STD-810F, Method 503.4

Drip Test

As per MIL-STD-810F, Method 506.4, Procedure III

Fungus Test

As per MIL-STD-810F, Method 508.5
Fluid Contamination As per MIL-STD-810F, Method 504.1

Corrosion Salt Fog Test

As per MIL-STD-810E, Method 509.3

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Attitude And Heading Reference System (AHRS) For Aircrafts


Aircrafts, civilian, transport or military, all require reliable attitude and heading information for control, high up in the sky where there is no visual reference available to understand whether or not the aircraft is flying level. This information is further utilized by the pilot to navigate and stabilize the aircraft during the flight operations. The attitude and heading information is displayed on the Primary Flight Display (PFD)/Multi-function Display (MFD)/Independent Standby Instrumentation System (ISIS) to provide visual aid to the pilot about the orientation and heading information. An aircraft generally has a 2nd or 3rd level of redundancy for INS-GPS to make system fault-tolerant. This redundancy being achieved by introducing alternate INS-GPS/AHRS to take care of failure cases in the emergency situations. The Attitude and Heading Reference System (AHRS) is preferred as a redundant system in the avionics configuration in the aircraft for standby purpose. The AHRS consists of a cluster of 3-axis accelerometer, 3-axis gyroscope, and 3-axis magnetometer. The AHRS is used to provide additional means to get the attitude (Roll, Pitch), acceleration, angular rates and heading parameters of the aircraft.


Aeron’s AHRS, OCT2-AN5300S, is an Airworthy AHRS designed and developed for an in service aircraft.  The unit has been designed as per DO-254 standards and qualified as per MIL-STD-461E, MIL-STD-810G, and DO-178B, Level B+ with 100% MC/DC coverage. The system has been accorded the CEMILAC (An Indian Airworthy Certification Agency) certification. The AHRS gives attitude and magnetic heading information of the aircraft.  It comes with a standard RS-422 serial interface. It consists of MEMS-IMU with a built-in magnetometer. It also accepts data of external airspeed and external magnetometer data. The heart of the system is Extended Kalman Filter (EKF) based estimator which fuses information taken from inertial sensors (accelerometers), rotational sensors (gyroscopes), internal and external magnetometers and external aiding sensors like (GNSS/IRNSS velocity, true airspeed, magnetometer, etc.) in order to continuously estimate attitude and heading of the aircraft. It has multiple levels of sensor redundancy to handle failure cases. The AHRS comes with a user-friendly compass swing tool for calibration of magnetometer. It also facilitates in-situ programming of the Operational Flight Program (OFP) software. The OCT2-AN5300S has been successfully tested for entire flight envelope and in highly dynamic (2g, 3g and 4g) manoeuvres.


The AHRS, OCT2 AN5300S can be used as a secondary system for attitude and heading information as a stand by instrument. It can be interfaced with Attitude Indicators, integrated Secondary Flight Displays (iSFD) to provide an alternate means for real time attitude and heading awareness.

AHRS for Primary/Secondary Flight Displays

Flight Display

Flight displays, specifically, attitude indicators are an essential part of any aircraft avionics and are used for indication of attitude, heading, rate of turn, turn coordinator, altimeter, and true airspeed. The attitude indicators (AI) get the attitude and heading information from an external AHRS or a built-in AHRS. The aircraft has multi-level redundancies to display basic flight parameters (Attitude, Heading and Altitude) on the flight displays. Generally, there is an independent secondary flight display system connected to a standby AHRS which is also powered independently so in case the primary power fails, the pilot can still get a sense of aircraft’s attitude and heading when there is not other external visual reference possible.


Aeron’s AHRS OCT2-AN5300S is an airborne qualified system and delivers TSO compliant performance in attitude, heading, acceleration and angular rate data for a wide flight envelope, even in high manoeuvres. The OCT2-AN5300S can take external true airspeed (TAS) aiding input which is further utilized for attitude corrections when subjected to pseudo-forces. The raw acceleration data helps to determine the skid angle for turn coordination. The AHRS has in internal magnetometer to estimate the magnetic heading parameters by sensing the Earth’s magnetic field. The aircraft instruments generate varying magnetic fields which can make it difficult to use internal magnetic field.  OCT2-AN5300S AHRS also accepts external magnetic field data input to generate the magnetic heading parameter. OCT2-AN5300S comes with standard RS-232/RS-422 interfaces and can be easily integrated with standalone flight displays or can be integrated as a part of flight instruments.

Product Documents



OCT2 AN5300S is qualified for DO178 Level B+. The qualification included 100% MC-DC coverage.

Yes, the unit has been tested rigorously and is being deployed and is in production for airborne applications.

At present this unit is CEMILAC certified. Please contact us on sales@aeronsystems.com regarding this.

OCT2-AN5300S can accept data from external magnetometer and air data computer. More details are available in the user manual.

The default baud rate for OCT2 AN5300S is 38400. 

The nominal operating voltage for the device is +28 V DC.

Yes, the OCT2-AN5300S may be considered as a form-fit-function equivalent of Crossbow GRU. The mounting arrangement for the two units is identical and the electrical and software interfaces are very similar.

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